Browse Forums Eco Living Re: Rainwater tank issues 4Feb 11, 2018 6:21 pm The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Rainwater tank issues 5Feb 11, 2018 7:37 pm 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 tank issues 7Feb 12, 2018 5:36 pm 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 tank issues 9Feb 13, 2018 10:57 am 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 tank issues 11Feb 13, 2018 7:47 pm As usual, expert advice form SaveH2O with astonishing attention to detail. We are indeed fortunate to have a person with so much detailed expertise on this forum. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Rainwater tank issues 12Feb 13, 2018 7:57 pm Monty4 The overflow from the tank flows under the house slab to a stormwater sump in the north eastern corner of the block. There is one other inflow to this sump which collects ag drain/landscaping runoff. Sorry...meant south east corner. Re: Rainwater tank issues 13Feb 13, 2018 11:06 pm Monty4 How do you go from the Lake Mac 1:20 IFD of 180mm/hr to the 3.03mm/min intensity over 5 minutes? Why is it not 180/12=15? I always bring the figure back from a 5 minute rain intensity duration figure to a 1 minute average figure when calculating flow rates. The 3.03 referred to the 1:20 IFD, the 1:20 ARI is 3.0. Monty4 I have taken a closer look at the roof catchment area. The updated total is 227m2, with the south roof area having and area of 154m2 and the north 73m2. That is about 680 litres per minute during a 1:20 ARI, nearly 2 1/2 times the overflow pipe's capacity and more if the gutter area is not already included. The overflow as is can cope with a maximum 90 sq m roof catchment but that doesn't include a safety margin. There is another top inlet at the other end of the tank, it should also have provision for an overflow outlet. Have a look for a blank that has to be cut out. you might be able to buy a hole saw from the tank company. You could have that overflow fitted and the overflow modified inside the tank with a bell mouth and the external overflow pipe run alongside the tank to join the existing overflow pipe. It could be a challenge to fit a bellmouth on the existing overflow given the incoming water's flow path but having just one will do. You would still have to address the need for a flush valve on the horizontal wet system pipe coming from the south side. As a matter of interest, does the inflowing water pass through mesh at the top of the tank or does the pipe descend into the tank? The water should divert to the tank at the end opposite to where the pump is unless the pipe descends to a calming inlet but if it does descend to a calming inlet without having passed through mosquito proof mesh, then that is another area of non compliance. https://www.youtube.com/watch?v=ULj6Ar2ncLE&t=99s I am looking for a video that shows the depth and the amount of air that a fast flowing stream of water carries into a body of water after entry but no luck so far.It is a lot more dramatic than what is shown in the above video. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 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 tank issues 14Feb 15, 2018 1:33 am An addendum to my second post. The National Construction Code (NCC) comprises the Building Code of Australia (BCA) Parts 1 & 2 and the Plumbing Code of Australia (PCA) Part 3. The NCC is updated bi-annually on May 1 and the current edition is the 2016 version. The NCC can be downloaded free of charge. http://www.abcb.gov.au/Resources/Public ... ete-Series The screen shots below show the PCA: Page 71 Section D1. Page 120, STATE AND TERRITORY APPENDICES -VARIATIONS AND ADDITIONS...NSW. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ 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 tank issues 15Feb 15, 2018 5:18 am Thanks SaveH2O! You have been an absolute treasure trove of information and ideas. I intend to spend some time tonight consolidating all the input and proposing a pathway forward for your review. It is probably time to give the builder and plumber right of reply. Just to close off on "some loose threads".......... The PCA references the AS/NZS3500.3. Is there a way to access this standard easily? I note you generally need to fork out a not insignificant amount of money to buy it online. I would have thought that making access to relevant standards as easy as possible would have a positive impact on reducing build issues developing in the first place. SaveH2O There is another top inlet at the other end of the tank, it should also have provision for an overflow outlet. Have a look for a blank that has to be cut out. you might be able to buy a hole saw from the tank company. You could have that overflow fitted and the overflow modified inside the tank with a bell mouth and the external overflow pipe run alongside the tank to join the existing overflow pipe. It could be a challenge to fit a bellmouth on the existing overflow given the incoming water's flow path but having just one will do. This idea has merit, although the other overflow outlet is hard up against a wall that would make the plumbing a little complicated. I still can't visualise how the bell mouth would work inside this tank as the overflow outlet is so high in the tank??? SaveH2O You would still have to address the need for a flush valve on the horizontal wet system pipe coming from the south side. Yes!! Not quite sure how at this stage. The easiest way may be to direct the flushed water into the stormwater sump at the south eastern corner of the house. SaveH2O As a matter of interest, does the inflowing water pass through mesh at the top of the tank or does the pipe descend into the tank? The water should divert to the tank at the end opposite to where the pump is unless the pipe descends to a calming inlet but if it does descend to a calming inlet without having passed through mosquito proof mesh, then that is another area of non compliance. The incoming flow passes through a mesh at the top of the tank. By the way there is no insect mesh on the overflow outlet that I can see, nor on any of the downpipes (although we do have gutter guard mesh installed). Should there be for compliance? Would this requirement be in the NSW Environmental Planning regulations? SaveH2O Are you able to run a small 40-50mm pipe around the back of the house? I could have a simple solution for you. What was your thinking here? My intention is to draft a note and discuss with my Builder with the intention of defining a solution that complies with the relevant regulations and standards and delivers a workable solution. Pragmatically, I can see a potential solution being to remove the south side catchment from the rainwater harvesting system and direct all of this runoff directly to stormwater. This would reduce the rainwater harvesting roof area to 73m2. Unfortunately, we would end up using a lot more town supply and it would be very expensive water out of the tank given the investment in tank, pump etc. The buried connecting line running along the eastern side of the building would be blanked off with a flush valve fitted such that it could emptied and flushed occasionally. Not the ideal solution. Re: Rainwater tank issues 16Feb 16, 2018 2:11 am Monty4 The PCA references the AS/NZS3500.3. Is there a way to access this standard easily? Australian Standards are produced by Standards Australia, a non profit independent company. The Standards are sold under license by SAI Global. Libraries use to stock various Standards but a year or two ago the fee to do so increases significantly and so not many libraries stock them now. You may be able to find a library that stocks the superseded Standard or even find one that carries the current version. The rainwater harvesting regulations are all over the place yet nowhere. Part 2 of the NCC addresses drainage in 3.1 but rainwater harvesting doesn't get a mention. The PCA is also void. AS/NZS 3500.3 has a lot of detail about roof drainage but nothing about water tanks. AS/NZS 3500.1 Section 14 INSTALLATION OF WATER SUPPLY SYSTEM FROM RAINWATER TANKS has 2 pages about pipe markings, references to Standards for backflow prevention and a couple of other things but nothing about the overflow requirement or much else. AS/NZS 3500.1 Section 8, WATER STORAGE TANKS States: "8.1 SCOPE OF SECTION This section specifies requirements for the storage of water. NOTE: For connections of rainwater tanks, see Section 14." What a joke!!! BUT.....this is followed by: "8.2.1 General This section applies to tanks provided for the storage of water for the following purposes: (a) Sanitary flushing (b) Drinking water supply (c) Firefighting (h) Make up water" The list goes to (i) but the above designations and the text in Section 8 unquestionably refers to water tanks. (a) above could however mean to refer to a cistern but it is ambiguous as a water tank will often provide water to a cistern for toilet flushing. The point is that Section 8 includes the previously mentioned figures 8.2 and 8.3 for horizontal and vertical overflow pipe maximum flow rates for different size pipes (they go up to 200mm) at varying water level heights above the pipe's invert. The figures clearly show that your overflow is woefully inadequate and therefore not compliant IMHO. I would use this as the basis to prove the overflow's massive non compliance but you could also check with the Office of Fair Trading. I could scan and Email the charts if need be. Monty4 .......the other overflow outlet is hard up against a wall that would make the plumbing a little complicated. I still can't visualise how the bell mouth would work inside this tank as the overflow outlet is so high in the tank??? That would be the plumber's problem. An internal extended overflow pipe would have to extend downwards and then come up again so that it was vertical. A vertical orifice drains more efficiently than a horizontal one even without a bellmouth., for example, a horizontal and vertical 100mm pipe with a 100mm depth above the invert drain at 4.67 L/sec and 6.6 L/sec respectively. This equates to 280 L/min and 396 L/min respectively. I have been wondering whether you could have a horizontal overflow pipe extension inside the tank. If the pipe had a section of its 'belly' removed after the first 50mm, the water entering from underneath should make the drainage more efficient because the inflow at the end of the pipe and consequently the usual free surface vortex would be lesser. I haven't tested this though. Monty4 The incoming flow passes through a mesh at the top of the tank. By the way there is no insect mesh on the overflow outlet that I can see, nor on any of the downpipes (although we do have gutter guard mesh installed). Should there be for compliance? I couldn't find a You Tube video showing what is termed Plunging Water Jet Air Entrainment but there would be a massive amount of air entering the tank during heavy rain. A pump should never be installed under a wet system inlet. The overflow mesh is a mandated regulation but I am not sure where you would find it stated apart from regional health regulations if applicable. You know what they say about a rat up a drain pipe. I am not in NSW, I don't know the scope of the regulatory framework up there. Monty4 SaveH2O Are you able to run a small 40-50mm pipe around the back of the house? I could have a simple solution for you. What was your thinking here? The builder needs to rectify the installation and that will most probably entail establishing a storm water system in place of the south side wet system but you will also need an extended horizontal pipe fitted with a flush valve because the tall riser inside the north under house area also creates a sump. You really need to delete the south side downpipes because of the overflow issue and the low wet system sump unless you can cure the overflow inadequacy and the lack of a flush valve at the low point.The other problem is that if you do, you won't be harvesting as much water as you wanted to. I developed the Supadiverta which I retained rather than license and it would have been ideal for your situation provided that a 50mm pipe could come around the house below ground from the south side. The Supadiverta usually diverts to a valve fitted about 100mm above the bottom of the tank at the valves lowest point but I don't know whether the tank can be retro fitted with a 50mm valve because of the style of tank. Monty4 My intention is to draft a note and discuss with my Builder with the intention of defining a solution that complies with the relevant regulations and standards and delivers a workable solution. I doubt very much that the builder will know the regulations. Maybe a draftsperson designed the system. The tank was a terrible choice, I would have had a 2 or 3 tank settling system with the overflow at the infeed tank and the pump on the furthest tank. EDITED; Late hour typos...changed downpipes to wet system and changed sec to min. 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 tank issues 17Feb 16, 2018 4:43 am SaveH2O The figures clearly show that your overflow is woefully inadequate and therefore not compliant IMHO. Sorry, probably a silly question......but "IMHO"? If you would be good enough to scan the info and charts related to horizontal flow above invert, that would be much appreciated. SaveH2O An internal extended overflow pipe would have to extend downwards and then come up again so that it was vertical. Yes, I can understand the advantage of flow into an inverted bell mouth vs a horizontal pipe. The top of the bell mouth still needs to be as high as the top of the horizontal pipe exiting the tank. Looking at the arrangement at the top of my tank, I can't see how the bell mouth would fit under the top of the tank. Re: Rainwater tank issues 18Feb 16, 2018 10:52 am Monty4 Sorry, probably a silly question......but "IMHO"? In my humble opinion. Monty4 The top of the bell mouth still needs to be as high as the top of the horizontal pipe exiting the tank. Looking at the arrangement at the top of my tank, I can't see how the bell mouth would fit under the top of the tank. The return vertical pipe should only come up as high as the overflow's invert as a maximum. A small drain hole would need to be drilled at the pipe's lowest point. PVC becomes malleable when heated and you could mold a bellmouth of sorts from a fitting (easiest) or the pipe. There are videos on You Tube showing how to do this. https://www.youtube.com/watch?v=fzdnlBkG2mI A big possible/most probable problem is with the tank's design and the inflow pipe...the overflow's extended internal orifice obviously cannot be under the wet system flow path. This is why I have been thinking of an internal extended short horizontal pipe or fitting with part of the bottom section cut out (or drilled with holes) but it too can't be impacted by the inflowing water because of the stress on the fitting. The pipe or fitting needn't be long though. 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 tank issues 19Jun 29, 2018 5:00 pm To close this thread off...... In consultation with our builder, it was agreed that he would reduce the roof catchment being diverted to the tank to the northern roof area only (about 1/3 of what it had been). The charged underground system now has a screw cap in the storm water sump that can be removed to allow the system to be flushed. We have had a few torrential winter downpours since this modification and no tank over flows ! Yeehah!! Clearly the cost has been a reduction in the catchment and we will spend more often over the dryer months with an empty tank, but we are happy with the outcome that we have got to overall. Many thanks to SaveH2O for your valuable advice. Re: Rainwater tank issues 20Jul 16, 2020 9:20 pm My wife and I have just moved into a house with 3 x 3000 litre water tanks in Heathmont VIC, and almost zero knowledge of them. Almost all of this thread goes over my head. We had a plumber do some other work on a toilet and determined that 2 of the tanks are joined together, and feed the toilets and laundry via a pump and tank to main auto changeover switch, although the pump was unplugged when we got here. There is also a tap that appears to make the tanks feed the entire house, this was open, even though the pump was off. That tap is now off for the moment. Inlet filters on the top of each tank had a couple of cms of sludge plus a ton of leaves and other much. I have cleaned them and we are now using it for toilets and laundry, and looks/smells clean to the eye/nose. Can someone reccomend a tank specialist to come out and assess the entire system and give us some advice on it. We would be interested in if it can be used for showers and/or hot water and issues with that. 18 90481 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 31280 Grate, thank you! RexChan if thats the reason i could sleep well without thinking about additional cost. But 1st i'll need to read about NRV cleaning/replaing stuff. I… 7 31155 |