Browse Forums Eco Living 1 Aug 24, 2014 11:10 pm Hi all, Have read a lot of useful and confusing information about rainwater harvesting and I want to get a better handle on what we should be doing - for longevity and safety of the system. The reasons for knowing more (apart from just knowing more !!) are this - - we built in 2010 and had our 6000L tanks installed by a "rainwater professional" the connections around the pump started leaking recently and we were told the install was "crap" and we were lucky it had not failed earlier - we will inevitably have a wet system and I don't think most people unless they read on forums like this and ata for instance know what the implications of stagnant water are - we have a first flush system fitted at the top of the riser - this is pretty useless....isn't it.....I still don't understand despite reading lots where it should be - we have 75mm downpipes that bend at 90 degrees twice as the run down the walls (ie follow the eaves) - we have our roof vacuumed every 6 months and the downpipes are almost all (usually 5/8) blocked by the 6 month mark - our 3.5 year old rainbank mark 3 has started leaking - and is no longer available due to some patent issue - we use rainwater 10 months of the year for our toilets x 2 and laundry - it is not used on the garden So what we want to do (if its the "right thing to do" - and this is where any advice is appreciated - building a 364 sqm house 35mx10m rectangle - no valleys in roof - colorbond - there are 8 downpipes - I want 90mm down pipes at least at 45 degree angles to reduce blockages - leaf eaters at every down pipe (which ones are best) - where should first flush diverter/s be - we want to have at least a 7000 litre tank (above ground) if not two at 14000l - we will be using a tank vac device - is a rainbank/switching device necessary or is it more effective just to switch pump off when tank low -Sorry for long post if guess my question is -- best leaf eaters -- where to put first flush diverters -- and one thing I can't get my head around how do they send 8 downpipes (if we can ) to one tank and how does the overflow cope -- postcode 5068 We have separate plans on our engineering for a detention system - the rainwater engineering is two downpipes to a 1000L tank Thanks for reading and any input Re: Rainwater collection - questions?? 2Aug 24, 2014 11:30 pm Have you looked at the Supadiverta? That is what I am going to get for mine with 10k litre tank. As for the pump- look at the rainwater 101 thread, it mentioned about VSD pump in whixh I am looking at a grundfos CME3-62 pump. SaveH2o will be able to advise more. http://boostaoakfordsa.wordpress.com Site works: 26/8/14 Trench: 2/9/14 Slab: 8/9/14 Frame: 18/9/14 Bricks: 24/10/14 2nd fix: 24/11/14 Handover: End Feb 2015 Re: Rainwater collection - questions?? 3Aug 24, 2014 11:54 pm Thanks !! Just was watching you tube video explaining the supadiverta - concept amazing - but I don't know if I want the multiple pipes everywhere - will have to consider vanity and practicality. Reading through 101 thread for second time.... Re: Rainwater collection - questions?? 4Aug 25, 2014 5:00 am bluesteel Have read a lot of useful and confusing information about rainwater harvesting Rainwater harvesting best practice is simple common sense. Common practice is mostly sub standard work with little thought or care applied. bluesteel - we built in 2010 and had our 6000L tanks installed by a "rainwater professional" the connections around the pump started leaking recently and we were told the install was "crap" and we were lucky it had not failed earlier About 95% of the rainwater harvesting installations that I see are sub standard, are you able to post a photo or two so that a critique can be given? bluesteel - we will inevitably have a wet system and I don't think most people unless they read on forums like this and ata for instance know what the implications of stagnant water are Leaf diverters are compulsory in most northern areas of Australia if wet systems are fitted but not so the southern States...but they should be. If you have a standard wet system and are on flat ground, it is very difficult to avoid a foul sediment build up in the pipes due to the difficulty of flushing a below ground system. If you have read in other threads about the benefits of having a low restriction inlet coupled with a sediment trap and leaf diverters, you will know that wet systems can in fact have clean pipes and divert clean water, improvements learned from our Supadiverta development program. bluesteel - we have a first flush system fitted at the top of the riser - this is pretty useless....isn't it.....I still don't understand despite reading lots where it should be Absolutely useless and a waste of water and money...the flush will still be in the downpipe at the other end and only the settled water held in the vertical riser since the last rainfall will fill the first flush. Practically every photo you see of water tank installs in the different Homeone threads show this type of installation. bluesteel - we have 75mm downpipes that bend at 90 degrees twice as the run down the walls (ie follow the eaves) - we have our roof vacuumed every 6 months and the downpipes are almost all (usually 5/8) blocked by the 6 month mark 75 mm downpipes are small and the water drains from the gutter to the downpipe via a pop that is smaller again. Some leaves form rafts, particularly gum leaves and these will lay across a small opening. For best results, larger 90mm round downpipes are needed. bluesteel - our 3.5 year old rainbank mark 3 has started leaking - and is no longer available due to some patent issue I know someone who has had 6 RainBanks...the first 5 failed and the replacements restarted the warranty. The 6th was starting to play up while still in warranty and so he (recently) ditched it. Unfortunately, the trusting home owner often ends up with a product that the plumber or water tank supplier has a commercial relationship with. SA has inserted a variation in the Plumbing Code of Australia (PCA) Appendix B1.2 (iii) (d) which does not allowed the use of cheaper, bullet proof manual mains water switching devices, only dearer automatic ones as a compulsory fitting when connecting tank water to the house water supply. "(iii) The requirements of this Part. (d) Where a rainwater water service from a rainwater tank is permitted to interconnect with the water service from a water main supply, the following applies to Class 1 buildings and extensions or additions to Class 1 buildings where the roof area is not less than 50 m2. The supply to a fixture, appliance or water outlet shall be maintained by a device/mechanism that facilitates a seamless automatic switching from one water service supply to another and vice versa without the need for manual intervention." The automatic Acquasaver mains water switching device is unpowered as it works by hydraulic pressure and is virtually bullet proof but will still cost about $450. It is the best automatic option. http://www.claytech.com.au/claytech/pro ... cms6a.html You could also convert to a manual valve system and thumb your nose at the SA bureaucrats who thought they knew better than those who compiled the PCA. bluesteel So what we want to do (if its the "right thing to do" - and this is where any advice is appreciated - building a 364 sqm house 35mx10m rectangle - no valleys in roof - colorbond I take this as saying that you are building this house and not referring to the one you built in 2010 and living in now. YES/NO. bluesteel my question is -- best leaf eaters -- where to put first flush diverters -- and one thing I can't get my head around how do they send 8 downpipes (if we can ) to one tank and how does the overflow cope -- postcode 5068 The best leaf diverter isn't on the market is the ICON Leaf and Debris Controller. It has a continuous steep slope outer filter that flushes leaves and a large mosquito proof inner filter. The filter is accessible for maintenance by pulling out a 'drawer' at the bottom. First decide as to whether you need first flush diverters (FFDs) given that you don't require water for potable use. If used, FFDs should be fitted to the downpipes. There is a lot discussed about FFds in the rainwater 101 thread. If possible, use a settling tank system that will deliver decanted water to the tank that supplies the pump. Basically what you need to do is calculate inflow rates based as a minimum on the inflow rates to the tank during a 1:20 Intensity Frequency Duration as this is what your eaves gutters must be calculated to drain for compliance. The calculation therefore will be your roof area harvested x the area's 1:20 IFD 5 minute intensity. I have just checked your postcode and your 1:20 IFD is 2.00 mm/minute. 1mm on 1 sq m = 1 litre and during a 1:20 ARI, your 364 sq m roof will be delivering 728 litres per minute. The diverted water pipe size calculations depend on what roof area serves a common wet system pipe and the available head pressure that services that wet system. If water will be diverted to more than one tank, then it becomes easier. The regulations on water tank overflows are either very poor or non existent plus additional to the equation is the fact that overflows outlets are also meshed with <1 mm aperture mesh with about 50-55% open area. I recommend determining a 90 mm overflow as a maximum 165 lpm and a 100 mm overflow as 220 lpm but the flow will be greater if the tank has mitigation (more height) above the top of the overflow pipe. A 100mm unmeshed horizontal overflow outlet is rated at 280 lpm as per AS 3500.1 Table 8.2. Toricelli's Law is used for a tank's horizontal overflow calculations. Re the Supadiverta (my product) that boosta mentioned, this can eliminate the worry about tanks overflowing when numerous downpipes are harvested and in many situations, it can eliminate the water tank overflow altogether. You can also have a flashing made to cover the area under the Supadiverta. Some people have the flashing rendered on big dollar new homes. bluesteel We have separate plans on our engineering for a detention system - the rainwater engineering is two downpipes to a 1000L tank A 1,000 L detention tank is very small, particularly off a 364 sq m roof! Is there a Permissible Site Discharge (PSD) flow rate mentioned? A detention tank restricts the amount of water being discharged. If there isn't a restricted discharge flow rate requirement, then what is the point of having a detention tank? EDITED 14/03/18. Updates. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Rainwater collection - questions?? 5Aug 25, 2014 12:15 pm Thank you so much for your input ( I was hoping you would give me some advice) sorry my post was a bit addled late last night. I will read your response in detail tonight but we are building a new house have just sold the one built in 2010....want to do better this time, Re: Rainwater collection - questions?? 6Aug 25, 2014 3:59 pm bluesteel we are building a new house have just sold the one built in 2010....want to do better this time, I should have seen the text under your post and realised you were building. It was a late night for me also and I was rushing as I only saw your post when I was finishing some work. What will the roof pitch be? Just be aware that the worst possible place to fit a downpipe is at the end of the wall. I use the term "aesthetics subjugating function". 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Rainwater collection - questions?? 7Aug 25, 2014 9:10 pm SaveH2O bluesteel Have read a lot of useful and confusing information about rainwater harvesting Best practice is simple common sense. Common practice is mostly sub standard work with little thought applied. bluesteel - we built in 2010 and had our 6000L tanks installed by a "rainwater professional" the connections around the pump started leaking recently and we were told the install was "crap" and we were lucky it had not failed earlier Are you able to post a photo or two so that a critique can be given? I can and will but the guy who came and tightened it all up said it was poorly put together - he didn't mention the first flush diverter position bluesteel - we will inevitably have a wet system and I don't think most people unless they read on forums like this and ata for instance know what the implications of stagnant water are Leaf diverters are compulsory in most areas if wet systems are fitted but not so the southern States...but they should be. If you have a standard wet system and are on flat ground, it is very difficult to avoid a sludge build up in the wet system pipes due to the difficulty of flushing the system. If you have read in other threads about the low restriction inlet coupled with a sediment trap and leaf diverters, you will know that wet systems can in fact have clean pipes and divert clean water. We currently have no leaf diverters the new house will, also the sediment trap and the low restriction inlet will be incorporated in the design. I understand the sediment trap diagram but can't really get my head around the low restriction inlet - a diagram would be great!! bluesteel - we have a first flush system fitted at the top of the riser - this is pretty useless....isn't it.....I still don't understand despite reading lots where it should be Absolutely useless...the flush will still be in the downpipe at the other end and only the settled water held in the vertical riser will fill the first flush. Practically every photo you see of water tank installs in the different threads and blogs show this type of installation. Ours is exactly the set up you posted in the 101 thread - ie terrible and useless bluesteel - we have 75mm downpipes that bend at 90 degrees twice as the run down the walls (ie follow the eaves) - we have our roof vacuumed every 6 months and the downpipes are almost all (usually 5/8) blocked by the 6 month mark 75 mm downpipes are small and the water drains from the gutter to the downpipe via a pop that is smaller again. Some leaves form rafts, particularly gum leaves and these will lay across a small opening. For best results, larger round downpipes are needed. The Leaf Safe Guttering system works by surface tension and it keeps the gutters leaf free and the water pristine. The inventor is a friend of mine, is based in Adelaide and I know the system well. For retro fitting, you need to have the existing gutters lowered and so there is a cost impost. http://www.leafsafeguttering.com.au/ bluesteel That looks great but I don't know if we would go that way in the new house (have just sold the 2010 house), any worries to consider with the new stratco edge guttering profile to be wary of? - our 3.5 year old rainbank mark 3 has started leaking - and is no longer available due to some patent issue I know someone who has had 6 RainBanks...the first 5 failed and the replacements restarted the warranty. The 6th was starting to play up while still in warranty and so he (recently) ditched it. SA has gone against the Plumbing Code of Australia (PCA) and not allowed the use of cheaper, bullet proof manual mains water switching devices, only dearer automatic ones as a compulsory fitting when connecting a water tank to sanitary flushing. The Aquasaver is unpowered, works by hydraulic pressure, is classified as automatic and is virtually bullet proof but will still cost about $450. http://www.claytech.com.au/claytech/pro ... cms6a.html You could also convert to a manual valve system and thumb your nose at the brainless SA bureaucrats who thought they knew better than those who compiled the PCA. The claytech looks good, we would rather just switch the pump off ourselves when tank low, I didn't know SA has a compulsory rule of fitting an automatic device bluesteel So what we want to do (if its the "right thing to do" - and this is where any advice is appreciated - building a 364 sqm house 35mx10m rectangle - no valleys in roof - colorbond I take this as saying that you are building this house and not referring to the one you built in 2010 and living in now. YES/ bluesteel my question is -- best leaf eaters -- where to put first flush diverters -- and one thing I can't get my head around how do they send 8 downpipes (if we can ) to one tank and how does the overflow cope -- postcode 5068 The best leaf diverter isn't on the market yet and may not be for a while due to time constraints. The Leaf Eater Advanced is probably the best of the current lot. Don't buy one with a coarse outer mesh and a fine inner mesh. First decide as to whether you need first flush diverters (FFDs) given that you don't require water for potable use. Also use a settling tank system. If used, FFDs should be fitted to the downpipes. There is a lot discussed about FFds in the rainwater 101 thread. Your question about water tank overflows is justified. The regulations on this subject are either very poor, just plain wrong or non existent plus additional to the equation is the fact that overflows are also meshed and that 1 mm aperture mesh has about 40-50% open area. I recommend determining a 90 mm overflow as 175 lpm and a 100 mm overflow as 245 lpm. Basically what you need to do is work everything out based on the inflow rates to the tank during a 1:20 Intensity Frequency Duration as this is what your eaves gutters must be calculated to drain for compliance. The calculation therefore will be your roof area harvested x the area's 1:20 IFD 5 minute intensity. I have just checked your postcode and your 1:20 IFD is 2.00 mm/minute. Our roof is 374sqm - if we want to harvest 3/4 of the roof does it follow that 1:20 is 0.75x374x2 = 561lpm ie more than the tank vac would cope with - how would we overcome this apart from reducing the roof harvested? The TankVac drains at about 540 lpm. It is a superior syphonic system and the outside 80 mm DWV pipe is 900 mm long and vacuum breaks into (usually) a 100 mm DWV pipe. Re the Supadiverta that boosta mentioned, this can eliminate the worry about tanks overflowing when numerous downpipes are harvested, in fact, it can eliminate the need for an overflow altogether. You can also have a flashing made to cover the area under the Supadiverta. Some people have had the flashing rendered on big dollar new homes. Cool idea rendering over it but out of our price range also render is another maintenance issue... But I would seriously consider the supadivertas to the south side of the house - the house's long axis is north south - the south being the narrow unseen side. bluesteel We have separate plans on our engineering for a detention system - the rainwater engineering is two downpipes to a 1000L tank A 1,000 L detention tank is very small, you can use a retention tank as a retention & detention tank. Our engineering has a minimum 1500L underground detention tank volume and the engineer has just stuck at 1000L tank as the rain harvesting tank collecting only one downpipe - along with 8 downpipes 4 at each corner - where is better placement - one centred on the small sides of rectangle and 3 spaced along each long side? How come engineers always place them in the corners? Could I also just say as many have done before - thank you - for taking the time - to educate, improve and share - I really appreciate it. Re: Rainwater collection - questions?? 8Aug 26, 2014 3:02 am bluesteel Could I also just say as many have done before - thank you - for taking the time - to educate, improve and share - I really appreciate it. And thank you for expressing your appreciation. I have conversed with some really good people on this forum and it is something that I look forward to and also benefit from. Re the pump, a common mistake installers make when installing a pressure pump is to connect the pump's suction hose to a 90 degree elbow fitted directly to the pump's suction side. The suction hose should respect a straight length of at least x 8 the hose's internal diameter immediately before the suction end to safeguard against cavitation. Another mistake is not using a flexible coupling between the tank and the pump. Other mistakes include exposing the pump and pressure controller to the elements, fitting the pump to a very low tank outlet that draws water from the anaerobic zone and also incorrectly sizing the pump and/or pipes. Low Restriction Inlet. I call it this because it provides a low restriction wet system flow path to the tank because it bypasses the vertical riser. It also flushes the wet system every rain event, only retains water to the level of water in the tank when it's not raining, oxygenates the anaerobic zone and supplements the wet system's flow capacity. To fit one, water must first pass through mosquito proof mesh before entering the tank, this is achieved by fitting mosquito proof leaf diverters to the downpipes. In a nutshell, the wet system pipe is reduced in size and the smaller pipe then connects to a same sized inlet fitted about 100 mm above the bottom of the tank...but it can be higher. The inlet also needs to be fitted within 75 degrees either side of an external pump's draw valve. To plumb it, you first fit a tee at the base of the vertical riser instead of an elbow. 100 mm u-PVC DWV pipe must be used. You reduce the tee's additional horizontal opening with a DWV invert taper and fit either a 50mm or a 40mm pipe to the taper. You then adapt the pipe to a UV stabilised flexible hose which connects to a valve at the tank. There are several ways to do this but you would usually fit a threaded elbow to the tank's inlet. Also look at photos 11 & 12 on the Supadiverta Pipe and Fittings page. https://www.supadiverta.com.au/pipes---fittings.html STRATCO EDGE GUTTERING I have never seen it. Certainly looks stylish. http://stratco.com.au/pdf/brochures/Gut ... 8980870000 If you connect a water tank to a WC, the Plumbing Code of Australia states: “PART 7—REQUIREMENTS FOR WATER SUPPLY WORK 10 Definitions In this Part— automatic or manual interchange device means a device that by way of manual or automatic means can alternate between varying water sources; Requirements where rainwater used for sanitary flushing. (1) If a reticulated water supply from a network utility operator is connected, or proposed to be connected to a building where a rainwater tank is installed for the purpose of sanitary flushing, an automatic or manual interchange device that allows alternate use of water from the rainwater tank or the reticulated water supply must be installed to ensure that there is a continual supply of water for sanitary flushing”. South Australia does not allow manual devices but automatic mains water switching devices also includes the RainAid. These cost about $140 plus plumbing. The RainAid is not connected to an electrical source. The RainAid automatically provide an additional 100 mm water depth when the tank reaches a set low level. In NSW, Sydney Water stipulates that the 2 lpm version is used. The pressurised mains water that these devices supply the tank is then pumped to the cistern etc. For this reason, they are best used in areas that have a consistent rainfall and the tank should be close to a mains water supply. http://www.apexvalves.co.nz/plumbing/apex/rainaid.html bluesteel Our roof is 374sqm - if we want to harvest 3/4 of the roof does it follow that 1:20 is 0.75x374x2 = 561lpm ie more than the tank vac would cope with - how would we overcome this apart from reducing the roof harvested? It is extremely rare for downpipes to harvest equal roof areas. Roof slopes also mean that during wind driven rain, more rain will fall on one side of the roof than the other. The above aside, your figures are essentially correct. Tanks however do have some mitigation capacity and so the infeed Vs overflow rate differential is little to worry about, the main worry if the tanks were full during heavy rain would be the weather falling on the side where most of the downpipes were diverted to the tank or if the rain intensity exceeded a 1:20 IFD. There are frustrations with harvesting rainwater: You need to harvest the maximum number of downpipes during light rainfall but that becomes a problem during heavy rainfall. You can however have a hybrid system whereby you can harvest numerous downpipes during light rainfall but have some of those downpipes automatically divert to stormwater when the tank fills. The Supaiverta fulfills this requirement. bluesteel Our engineering has a minimum 1500L underground detention tank volume and the engineer has just stuck at 1000L tank as the rain harvesting tank collecting only one downpipe - along with 8 downpipes 4 at each corner - where is better placement - one centred on the small sides of rectangle and 3 spaced along each long side? How come engineers always place them in the corners? It sounds like your roof area will produce more run off during a 1:20 IFD that the council allows. What is the maximum permissible discharge from the detention tank and/or you maximum permissible site stormwater discharge? It is easy to incorporate a detention compartment into a retention tank and it is also much more efficient to do so. DOWNPIPES: Downpipes are positioned at the end of walls for aesthetics, not efficiency. Water should flow to a downpipe from both sides for best performance and having a straight run of guttering is the best case scenario. I prefer having the downpipes away from the ends and closer together to improve the slope. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Rainwater collection - questions?? 9Aug 26, 2014 8:20 am Quote: STRATCO EDGE GUTTERING I have never seen it. Certainly looks stylish. http://stratco.com.au/pdf/brochures/Gut ... 8980870000 That does look good. I noticed they do mention to have sufficient overflow measures so that it doesn't overflow back in to the building being such a high fronted gutter but their diagrams showing their mounting bracket don't seem to address that. Re: Rainwater collection - questions?? 10Aug 26, 2014 3:52 pm AS/NZS 3500.3 (2003) Clause 3.5.1 states: “Eaves gutter systems, including downpipes, shall be designed and installed in accordance with Clause 3.2 so that water will not flow back into the building.” There are several overflow provisions to choose from and flashing would be one option in this instance. The gutter has a large carrying capacity and that translates to weight. Most eaves gutters will open a gap between the gutter's back wall and the fascia when weight comes into play but there are also fastening systems that provide a permanent 10 mm gap between the gutter's back wall and the fascia. Have a look at the video in the link below. Note that I do not endorse all of the information given on this website. http://www.guttergrip.com.au/ Also look at the two different slotted gutters in the video, one has the totally inadequate slots as originally sold, the second complies with current design mandates. It has always amazed me that slotted gutters were originally designed and sold with such a poorly designed and inadequate overflow provision. Just unbelievable stupidity and yet another example of aesthetics subjugating function, an all too common practice that still prevails with different products due to point of sale visual appeal often being the sale clincher. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Rainwater collection - questions?? 11Aug 26, 2014 10:32 pm I understand the low restriction inlet and sediment trap. The supadiverta pics helped. I have attached what was in our engineering - I don't understand this - it refers to sump volume is the conclusion 1527L sump volume with a 4l/s pump. http://i728.photobucket.com/albums/ww288/ambipup05/Tank.jpg http://i728.photobucket.com/albums/ww288/ambipup05/tank2.jpg It refers to 20l/s as the maximum discharged allowed from the site. You mentioned being able to divert downpipes simply when the tank is full so that in light rain/or tank empty we can harvest them all - how would this work. We will make sure if we go with the edge profile it is installed as per directions because obviously weight will be an issue. So are you also saying that 100mm downpipes are the way to go? Thank you again. Re: Rainwater collection - questions?? 12Aug 26, 2014 10:33 pm Also, forgot, how can detention and retention be combined. I thought surface water would not ideally be mixed with roof water? Sorry if dopey questions. Re: Rainwater collection - questions?? 13Aug 27, 2014 11:07 pm bluesteel You mentioned being able to divert downpipes simply when the tank is full so that in light rain/or tank empty we can harvest them all - how would this work You can divert the downpipes that harvest an area of roof that will not cause an overflow issue during a 1:20 IFD if the tank filled. If you use the TankVac, it will discharge the equivalent of 270 sq m of harvested roof during your regions 1:20 IFD rain intensity. The other downpipes can be harvested by Supadivertas and these will give the system a boost during milder rainfall when the tank isn't full. If the tanks fill, the water will automatically drain to the stormwater. They could harvest 100 or 1,000 downpipes if you had a large enough house without risk of the tank over-topping. bluesteel We will make sure if we go with the edge profile it is installed as per directions because obviously weight will be an issue. Only if they filled up...which would require a blockage...and even then the fastening system would I'm sure be designed to be suitable for purpose. bluesteel So are you also saying that 100mm downpipes are the way to go? The transition from 90 mm round to 100 mm round is when the gutter's cross sectional exceeds 6,700 sq mm as per AS/NZS 3500.3:2003 section 3, table 3.3. The BCA has an acceptable performance provision to fall back on but this is only stating something that just wouldn't be brought up. Looking at the gutter's sole, it is 100 mm but a 100 mm PVCu downpipe has an outside diameter of 110 mm. This had me raise my eyebrows as to how it would look...but a gutter that size would obviously have to be fitted with big downpipes. It's an interesting looking gutter and it will drain well but if you have 90 mm round PVCu pipes, then they will easily handle the heaviest of rain. Most houses have very poorly designed stormwater drainage anyway because they get passed and I couldn't see any problems with yours. My design observations are academic only. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Rainwater collection - questions?? 14Aug 28, 2014 1:04 am DETENTION STORAGE: I have had a look through the docs and I have some queries and observations. I take it that your stormwater mains pipe is uphill from your property . YES/NO? It would be better if I could see the drainage plans, eg, the pipe sizes and layout, the pits, sump dimensions-depth etc and the land contours but not having the info isn't a hindrance. OBSERVATIONS: They have used 10 year/10 minute ARI calculations for the paved area, open area run off and the roof drainage as required. Run off coefficients have also been used as required. All water is calculated as draining to a sump. The total amount of water calculated to drain to the sump during a 10 minute 1:10 ARI is 6,452 litres. They have selected a big pump that discharges at 4 lps (240 lpm) and a required sump capacity of 4,227 L which is a 10/10 ARI of a 15 minute duration. Although not stated, pumped systems require 2 pumps in tandem with alternating starts to protect the pumps against frequent cycling. The regulations are stated in AS/NZS 3500.3:2003 section 9. The ones that I want to point out are... 9.4 PUMPS The pumps shall be suitable for unscreened stormwater and shall be installed as follows: (a) Pumps shall be in duplicate. The maximum capacity of each pump shall be selected so that the capacity of the system receiving the discharge is not exceeded. The pump controls shall be set up to enable alternate pump operation at each start. In the event that the pump fails to operate when the water level in the wet well reaches the pump start, the other pump shall be activated and a visible alarm initiated. In the event that both pumps fail to operate, an audible alarm shall be initiated. (e) Pumps shall be controlled so as to limit the number of starts per hour to within the capacity of the electrical motors and equipment, and shall, as far as practicable, empty the contents of the wet well at each operation. I don't like pumped systems but a lot of the time, there is no option. You have no choice but to have a sump with the paved and open area run off as you have an apparent slope issue but do you have the height from the bottom of a TankVac 900 mm long outlet pipe to achieve gravity drainage to a LPOD? It is also noted that you have a detention basin capacity that reduces your required sump capacity from 4,227 L to 1,527 L. I believe that this is too small because if the tanks were full during a 1:20 IFD and all of the roof water was also draining to the sump, it would fill and overflow in 2 minutes...remember that the flow calculations are done on a 1:10 ARI. I think that the engineer has tried to be kind re the single pump and final sump volume but unless the SA Govt has also overruled the applicable AS, then it wouldn't pass an inspection if the inspector was competent. Having said that, it is academic anyway as a blackout caused pump failure is unlikely to last just 20 minutes. If at all possible, I would not have the tank overflow draining to the sump and that would eliminate 5 downpipes. The TankVac would flow (vacuum break) into a standing 100 mm DWV pipe and so it is easy to work out the applicable head from the site contours. bluesteel Also, forgot, how can detention and retention be combined. I thought surface water would not ideally be mixed with roof water? When I mentioned a detention tank, I was unaware of a drainage/site slope issue, I thought that you may have had a maximum allowable site discharge rate that you roof area may have exceeded during a 1:20 IFD. To use a tank for roof drainage detention, you simply use a tanks upper storage capacity as detention. A detention tank will start draining a limited flow through a small pipe once the bottom of the detention level has been reached. If the tank fills, it then discharges at a higher flow rate through a bigger overflow pipe. You might for example have a 10,000 L tank with the top 2,000 L held for detention. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Rainwater collection - questions?? 15Aug 28, 2014 1:33 am Yes you are right we are lower than the road. Sorry I did not even think to factor that in (sorry). and the house follows the contour - it drops 340mm (split). I did not factor in the tank vac being able to discharge to street. The engineering diagram follows - hope its possible to read http://i728.photobucket.com/albums/ww288/ambipup05/Contours.jpg Re: Rainwater collection - questions?? 16Aug 28, 2014 2:07 am One thing that I will have to revisit is the fact that the roof drainage is calculated as a 1:10 ARI and those calculated flow rates are used in the large table but further down they show the roof drainage as being 1:20 ARI and a discharge of 12.57056 lps (which is correct for your 1:20 ARI 5 minute average intensity) YET they state that the total discharge from the site is 16.57056 L/sec!!! How can this possibly be if the roof drains to the sump as indicated by the large table's calculations? What they have done is add the total roof flow during a 1:20 ARI to the pump's flow rate. I also love the way that some of these guys use figures like 16.57056 litres per second. Will look at the plan later today when I get a chance, it might shed light on the above. If I'm asleep within half an hour, I should manage 4.12637 hours sleep. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Rainwater collection - questions?? 17Aug 29, 2014 4:43 am Hi bluesteel, The table shows combined flow figures, not a sump storage sheet as the columns indicate. The run off from the paved area during a 1:10 ARI 10 minute event is an average of 136.6 L/minute and the open area run off is 50.6 L/Minute, a total average of 187.2 L/minute. No need for concern about the roof stormwater drainage and sorry if I caused any. Re the stormwater pipes, AS2200 states that the maximum flow through a DN 90 mm stormwater pipe is 360 lpm and a DN 100 mm pipe is 450 lpm. Obviously, your 374 sq m roof area will generate a lot more than this during a 1:20 IFD. Each pipe would be considered separate until the junction at which point the pipe will then have to be upsized. Given the flow discrepancy, this won't go unnoticed. EDIT: SaveH2O One thing that I will have to revisit is the fact that the roof drainage is calculated as a 1:10 ARI and those calculated flow rates are used in the large table but further down they show the roof drainage as being 1:20 ARI and a discharge of 12.57056 lps (which is correct for your 1:20 ARI 5 minute average intensity) YET they state that the total discharge from the site is 16.57056 L/sec!!! How can this possibly be if the roof drains to the sump as indicated by the large table's calculations? What they have done is add the total roof flow during a 1:20 ARI to the pump's flow rate. The above became clear once I saw that there was another pit in the NW corner to collect the surface run off that is then pumped to the sump at the SE corner. I initially understood that the sump was pumped. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Rainwater collection - questions?? 18Aug 29, 2014 5:40 am The north east corner (at the top) is the sewer. It is lower than the south east corner which is where the legal point of discharge is proposed to be. This block does not have one - the old house current drains into the garden (multiple rock pits all around) as many old houses in Adelaide do. The roof water I understand is separate - and it indicates a 150 diameter pipes in ground for the roof water. The detention for the surface water is at the lowest point in the north west corner draining to the same south east LPOD. It says there is 420 sqm open land and 126sqm of paving - I assume (and you know what they say about assumptions) the run off coefficient is how different surfaces run off ....are 0.1 and 0.9 respectively making this 42 and 113 - total 155 - 1:20-310lpm which is about 5 litres per second. I don't understand how they calculated volume of the detention. I think they refer to the 4427 and then reduced it by the volume of the dropped section of the garden as a swale. We wont be having a dropped section. So would a 5000 L underground tank cover the surface water detention requirement with a pump that can handle 4l/s (seems like it would be a big pump). The roof is as worked out before about 12lps. So I believe (.......assumptions......) For the roof 8 downpipes 90mm The lower section of roof (the bench level 99.4 floor level 99.6, 2.7 high walls) has 4 downpipes all with supa diverters going to the minimum 7000L tank (base at around 99.4 - height of the tank am thinking cantbe more than 2.1 (so outflow of tank would be at about 101.2) with a tank vac joining to the 150mm pipe going out to street discharge which is 100.04, Also we are to have an energy dissipating 30cm pvc sump before discharge. The other 4 downpipes with leaf eaters will go to street ( floor level is 300 higher for this part of the roof) discharging to the 150mm pipe going to the street. The wet system would incorporate a sediment trap and low restriction inlet. On the drawings they have indicated the square pvc pit at the boundary then drains to a box drain to the gutter. Thanks again for your help !! Re: Rainwater collection - questions?? 19Aug 04, 2015 1:02 am After a year posting about our rainwater system, I'm back. Yes it took a year to start building. We are at bricking stage and have to start considering where our tank slabs will go and just when you think you are ready committing to the position has made me worried. The story and the plan from all the helpful information (and amazing generosity of time) I have learnt from this website and a few others h2o, john's thread). Just tackling our roof water atm will look at surface drainage separately. Adelaide postcode 5068 1:20 ARI 2mm/minute Roof area 374sqm - a rectangle with 4 dp either side - with 8 downpipes (round pvc 90mm) Tanks will be plumbed to 3 WC and also a garden tap. The ground around the house is level at 99.55 - the gutter will be at 102.45 the street level is at 100.04 - ie we are lower than the street and will have a charged system. So this is what I am thinking after re reading the rainwater threads 1. Two tanks - both round to avoid slimline tanks (cleaning issues $$) - a 5000 round at the rear of the house (this will be base at 99.40 - so lower) and a 1000-2000L round near the house (base at 99.55) FIRST QUESTION - our pump will be located next to the house where the plumbing loop is located -does the 2nd tank need to be close to the house or can both tanks be distant to pump? Pros/cons for each option SECOND QUESTION - Rather than one 5000 at the rear is there any benefit having two 3000L at the rear (apart from the extra 1000L)? 2. Two runs of 100mm pipe from 3 pipes either side - (two front pipes will go direct to street) going to the rear tank. WIth a leaf eater/mosquito mesh at each downpipe. A low restriction inlet to both of the risers according to the excellent descriptions given. THIRD QUESTION - can someone please post a picture of diagram of a low restriction inlet - I get the explanation but can't find a diagram that I can understand : ( 3. So if all 6 DP go to the rear tank via two 100mm risers the overflow goes from this tank - we plan to use a tank vac and the rear tank will be connected to the side house tank which is plumbed to the pump - on a rainAid switching device with a 60L Davey pressure tank FOURTH QUESTION What level from the ground should the tanks be connected and how are they best connected so the side of house tank has the cleanest water? FIFTH QUESTION Does the side of the house tank also need an overflow? SIXTH QUESTION Any pump recommendations? More than happy to have my plan blasted to smithereens. We have 3m at the rear of house for tanks and 2m side setback for the side tanks. Just want to do it right. Re: Rainwater collection - questions?? 20Aug 04, 2015 1:03 pm Disclaimer – I know I have mentioned supadiverta a lot in my posts and some will see it as advertising for Dennis. I have spent a lot of time researching this product and numerous phone conversation/ emails with Dennis and have gone with this product for better rainwater harvesting as I am not a fan of the standard wet system. With the standard wet system (well supadiverta is still a wet system), the engineers only allowed for 4 DP to be harvested. I am using the supdadiverta ( harvesting 4 DPs at the moment), haven’t had time to do the 5th. The standard wet system, the water is always charged in your pipes under your pavers on concrete, I changed my site drainage plans so that the water in the pipes under the concrete are flowing out to the stormwater. I opted for my pipes to be “above”, not buried so that if it leaks, I can see it and fix the leak. Just means kids can't cycle all the way on the side. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ - (pic is abit "stretched") Some of your requirements are identical to mine. These are my experience with the supadiverta and am sure Dennis will further clarify your questions. 1st question – see question #6 and I have my pump next to my RWT and I had the plumber run the blue lines (and above pic) to the plumbing loop. One plumber just ask if I like to hear the noise of the pump running so it is preference. Just make sure you have ext powerpoint situated near the pump! 2nd question - It comes to space and $$. Do you need two tanks (5kl at rear) and (1k near house)? It will be similar to the big tank small tank setup on the supadiverta site. Obviously round RWT are cheaper than slimline. I was going to go with the big tank small tank set up but opted for the large tank. Did some calculation though the 13kl tank will only be full for a few days during winter, still I went for the largest possible. Also using crystal clear waterboy instead of tankvac. 3rd question – OK, I am assuming that you are using the standard wet system with 100mm pipes. I think Dennis did explained it in the above post (Low restriction inlet fittings and http://supadiverta.com.au/pipes---fittings.html - pic 11 and 12). My understanding (Dennis or someone correct me if I am wrong – eg. you reduce from 100mm to like 40mm and using pictures 11 and 12) connect to the inlet of the RWT, therefore no riser. The inlet is recommended to be 100mm from base of tank. This is my 50mm inlet (rainwater from DP to Supadiverta to RWT, the horizontal pipes are smaller in size for the Supadiverta) - Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ I had a 25mm riser as a test but that will not be used in future. I don’t have leaf eater/ mosquito mesh as it is eliminated with the supadiverta and I optioned my tank per Dennis’s recommendation. Tanks should be fitted with: • A low dedicated drain valve. • A suitably sized infeed valve fitted a recommended 100 mm above the bottom of the tank. • A pump draw valve, usually 25mm, fitted a recommended 80 mm above the bottom of the tank at its lowest point and within 60 degrees either side of the infeed valve. 4th question – don't quite get this question, are you saying that your rear (where RWT) is lower? 5th question – how far are the two tanks apart as you will need flexible hose for connection. 6th question – I’m using a grundfos and the distance between pump and house is ~ 7m – https://boostaoakfordsa.wordpress.com/2 ... peed-pump/ - posted an email response from Dennis. http://boostaoakfordsa.wordpress.com Site works: 26/8/14 Trench: 2/9/14 Slab: 8/9/14 Frame: 18/9/14 Bricks: 24/10/14 2nd fix: 24/11/14 Handover: End Feb 2015 DIY, Home Maintenance & Repair But if it is a ground level open pit, then it is not a charged system. No surprises there. The pipes have obviously been altered and there would be a reason for this.… 3 31392 Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 19663 There is a whole lot more to know than just the answers you seek but they are a good start. Overflow outlets have a mosquito proof mesh. These… 3 8479 |