Browse Forums General Discussion 1 Apr 16, 2013 9:02 pm Hi all,
We have an existing 4yo 4000L poly tank and would like to connect it to the builder-supplied 3000L slimline colorbond tank. I'm stumped on an exact design , can H1 members please provide opinions on how to do that ? From the house plan I can think of 2 positions to put their tank. The preferred position is drawn in the below picture, the other one closer to the middle of the house may not be suitable as tank length might block the laundry door - I don't have exact dimensions yet. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ The round tank definitely doesn't fit into the side setback due to regulations. We may put it in the drawn position, or further back for cosmetics. So the questions are: 1. Can a charged system be extended to accommodate it ? how exactly ? The height difference due to land fall may have some effect. 2. Should there be 2 charged piping systems ? how ? 3. If we can fit the slimline tank (maybe cut its size) in the other position closer to the middle of the house, one design is to direct the downpipes at the back, both ground & 1st floor, to the round tank (yeah, definitely 2 charged systems in this case). Is this acceptable ? 4. Is it better to get the builder to put in pipes, or is it an easy job for a plumber to do later ? 5. Any other design suggestions ? or should we simply sell the old tank and not worry about it ? Thank you all. Edit 1: image link Edit 2: add downpipes to image Re: Link 2 rainwater tanks some distance apart 2Apr 17, 2013 7:01 pm Check with a plumber, but I'm sure that if the two tanks are at the same level, you can link them with a buried (large) pipe and they will, in effect, be one large tank. From the pic, it looks like you would have to lower the existing tank to the level of the new one.. best of luck Re: Link 2 rainwater tanks some distance apart 3Apr 17, 2013 8:15 pm Can you show the approximate downpipe positions? What is the height of each tank? Are you required to use leaf diverters in your state? Have you considered the poly tanks overflow? Certainly doable if you can post the above info. The poly tank can be located a good distance from the house if desired. Re: Link 2 rainwater tanks some distance apart 4Apr 17, 2013 8:41 pm and in addition to jnk40's questions....where does your stormwater run? Remember that water will always seek its own level. So regardless of how the rainwater enters one tank, if you have a balance pipe between the 2, water will fill both up to the height of the tank with the lowest overflow. Distance between the tanks is irrelevant, all that does is slow down the timeframe between the 2 tanks coming back to level when water enters one tank. Diameter of the balance pipe also affects this timing. There are a number of ways to connect a balance pipe between tanks depending on the level of water quality you want in the tank(s) not receiving direct rainwater input. For a basic connection, you need a gate valve 150-200mm above the bottom of the tank on both tanks (so that is above the crud that will eventually form in the bottom of the tank) and a underground connector pipe either PVC or poly. If you use PVC, add a flexible connection between the gate valve and the PVC to allow for any ground movement. These are quite small tanks so there is a distinct likelihood that in a heavy rain event, the first tank will overflow before it could balance the inflow with the other tank. Therefore ensure that the overflow from both tanks is connected to your stormwater. Regards RiH Re: Link 2 rainwater tanks some distance apart 5Apr 17, 2013 9:30 pm Some more questions to those already posted. 1. What is the height of the gutter's sole (the underside of the gutter) to the ground at the downpipe nearest to the round poly tank as shown? 2. What size are the downpipes? If they are round, what are they made out of? 3. What is the height of the underside of the round poly tank's overflow outlet? The slimline's height may not matter. 4. Are there any concrete paths or other barriers between the house and where you propose to site the round poly tank? 5. What are you plumbing the tanks to? I assume that it is a new house. If you are plumbing to a cistern, the regulations require that you have an automatic or manual mains water switching device fitted. Most builders and plumbers will only tell you about the automatic ones like the Rainbanks and Waterswitch but you can have an Apex RainAid fitted that only costs around $130 (plus plumbing) and doesn't require mains power. In Sydney, you are required to only fit the version that delivers 2 litres per minute when topping up the tank. The RainAid operates from a pre set low level and only tops up the tank with an extra 100 mm depth of water. Also make sure that the pipework to a garden tap is not restrictive. The thread below discusses flow problems with a powerful pump (80 litres per minute) that connected to a tap approx 5 metres away. viewtopic.php?f=35&t=61588 You don't have to have a tank next to the house if there is room away from the house for two tanks. You are wise doing what you are doing now and getting good advice because the builder won't know and you will need to instruct the plumber. 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: Link 2 rainwater tanks some distance apart 6Apr 18, 2013 7:32 pm Thank you all for the replies. Here are more details: Can you show the approximate downpipe positions? Done on above picture - 2 from ground floor roof, 2 from first floor roof. What is the height of each tank? The poly tank height up to the dome is 1850mm, with the dome approx 200mm. Not sure about the slimline's height, but from old drawings provided it looked ~1.5m high. Are you required to use leaf diverters in your state? I prefer to have them, so will push the builder's contractor, or install later. Have you considered the poly tanks overflow? Yes, waiting for design ideas. where does your stormwater run? Probably along that side of the house. if you have a balance pipe between the 2 Is it a must ? At 150-200mm off the ground, it'd block side access to laundry. it looks like you would have to lower the existing tank to the level of the new one Need I do this everyone ? Probably need the demolisher to dig that area a bit and scrape the surroundings, and/or build a retaining wall (more $$ ). What is the height of the gutter's sole ? Not sure. Ceiling height 2.7m plus part of the slab minus the fascia / gutter height, so let's say 2.5m+ ? What size are the downpipes? If they are round, what are they made out of? Round PVC 90 or 100mm I think - need to check. What is the height of the underside of the round poly tank's overflow outlet? No existing overflow outlet - illegal I know. Didn't know better at the time and the Sydney Water inspector didn't say anything about it before approving their rebate 4 years ago. The rare overflow water just runs along our concrete path to the front garden & the neighbour's driveway to the street. Are there any concrete paths or other barriers between the house and where you propose to site the round poly tank? I plan to do a 900mm concrete appron around the house, but can leave a gravel base with top pebbles on the sides. Which is better ? What are you plumbing the tanks to? Good question. Builder provides it for outdoor garden use only, which makes sense due to the small size. I'm leaning towards leaving it like that for the following reasons: - Currently collecting from ~55sqm of roof, the 4000L poly tank runs out of water for gardening in 2-4 weeks without rain. - Costs to have pipes run to toilet cisterns, and the Rainbanks or Apex RainAid as suggested. - I'd love to have bidet seats in the future, so normal water taps are still required. if there is room away from the house for two tanks 2 tanks together with different materials & shapes are probably an eyesore You are wise doing what you are doing now and getting good advice because the builder won't know and you will need to instruct the plumber. Thanks, that's the idea. Re: Link 2 rainwater tanks some distance apart 7Apr 18, 2013 9:11 pm Ah sorry for the confusion Downtime. If the tanks were less that a metre apart then I would leave the balance pipe above ground. Otherwise, you would use a couple of 45 degree elbows after the gate valve to take it below ground and bring it back up again just near the 2nd tank with a couple more elbows into the 2nd tanks gate valve. Based on your tank heights above, the plan indicating a 50-60mm base height difference and an assumption that the bottom of the overflow on the slimline should be about 1350-1375mm above ground level. This height is the maximum height water can reach in both tanks as any extra water just overflows out the slimline's overflow. This means that your poly tank will only ever fill to a maximum height (in normal inflow conditions) to a height of 1300mm or so. This is 400-450mm below the maximum potential height in the poly and therefore the poly would never overflow. As a result you are not able to reach the full capacity of the poly tank in your current cofiguration. If you wanted to change it so that you are, you would need to lower the poly tank or raise the slimline or get a taller slimline. Raising the slimline by say 400mm or getting a taller slimline increases your total storage capacity as it would raise the height of the water in your poly tank by that same 400mm. Regards RiH Re: Link 2 rainwater tanks some distance apart 8Apr 19, 2013 12:28 am Thanks for the info downtime, exactly what I need but I do need to know as to whether the downpipes are 90mm or 100mm round as an adapter will affect the head. Given the total roof area harvested, I am assuming that they are 90mm. This is what we have... Having no overflow on the poly tank is ok as there is a way that you can fill a tank without it ever overflowing. It makes the install easier and cheaper. It isn't illegal to not fit a tank with an overflow in some circumstances. If storm water is diverted to a tank, the tank becomes part of the storm water system if it can overflow as the overflow must return to a legal point of discharge. If the tank cannot overflow, it does not require an overflow pipe. To do this entails having something in the same (storm water) system that can adequately substitute for the tank's overflow. You can easily fill a bigger and taller tank to full capacity (and without an overflow pipe fitted) away from the house and a smaller and lower tank at the house from the same pipe but automatically fill the smaller tank last! This also allows the bigger tank to be utilised as a settling tank and it is one option that I am considering for you. You would need to allow let's say 120mm for the 2 metre upslope between the house corner and the poly tank if you levelled the land so that the poly tank was level with the slope at the front of the tank. This is something that I would not normally recommend on any slope but I am not on site to be able to make a judgement in this case. As a rule of thumb from what I understand, you can only spare approximately 300mm when raising the poly tank above the ground level at the house corner with two of my options in order to fill the poly tank to full capacity. This would allow a concrete base. You could also consider a boxed compacted sand base. There are obviously other factors that we will skirt around for now, for example. the house should have as per the regulations a 1:20 slope away from the house for the first metre to stop water pooling next to the house. You also need to be aware of any below ground termite barriers when laying slabs or pipe work next to the house. It looks like 1600mm - 1650mm water depth would be ideal for the poly tank. While the two tanks could be filled independently or even from the same 'community" pipe, the balance line would have to be manually opened and closed or the situation that RIH described would eventuate if it was left open. A small balance line can easily be plumbed from the community pipe near to the smaller tank rather than from the bigger tank. One possible option to automate the balance feed would be to fit a 20mm JOBE valve at a low level to the slimline tank. These are shown as operating from very low pressure but you would need to investigate this. I have actually though of fitting one to one of my remote tanks to test it but have never got around to doing it. If it was fitted very low, you could maximise the head in the larger tank and still have the immediate downpipe diverting to the tank's top inlet as water would not be transferred from the charged community pipe until the smaller tank was nearly empty. If the slimline is corrugated sided, fitting the valve could prove difficult. http://www.irrigationwarehouse.com.au/category136_1.htm The downpipes would not be diverted, only the water, and the community pipe would only need to be a 40mm class 9 pressure pipe that has an actual internal diameter of 44.1mm. This size pipe is also easier to plumb under a path way. The slimline tank's position could present a real problem. The sketch shows that the downpipe is mid point but the slimline will also need a base. As you are restricted for space, it would be a real problem making the base and siting this tank as either one will block the storm water return. Your option would then necessitate blocking the present storm water access and plumb another one away from the tank for the tank's overflow pipe. The slimline will need an overflow pipe if the indicated downpipe diverts to the top meshed inlet. I don't like slimlines for a number of reasons and one of those is cost. Difficulty cleaning them is another. What is the maximum length and width that you can go? I always recommend two or more tall round poly's with small diameter bases rather than a slimline. Two round tanks could allow you to have a base that accommodated the downpipe return to storm water if the slimline does present the issue that I suspect it could. At this point, I can advise as to how you can divert to the poly without using a wet system vertical riser (which are real bad news) or needing an overflow pipe. The downpipe at the proposed slimline tank is a real worry and I need your further investigation and advise here. I will give you a few options once the slimline query is put to bed. 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: Link 2 rainwater tanks some distance apart 9Apr 19, 2013 1:20 pm Thanks RocksInHead & SaveH2O. From old diagrams they gave me & the supplier website, I think the tank they provided for an old customer was 1.48(H)x2.3(L)x1.0(W). I can certainly request a same capacity but higher (max 2.02) & wider (max 1.15) tank, hopefully at no extra cost. The brickwork there between the windows is 3m long, so leaving space for pipes the max length may be 2.7 - 2.85m. Heck, I might even upgrade to the biggest tank that fits in that space Yeah, the downpipe in the middle there is a worry that I definitely have to check with their draftsman or plumber. I think it's there because of the 1st floor's corner and can be moved. Where would you prefer it ? Oh, I forgot to show on the sketch a pipe from the 1st floor's back wall's gutter, about 3.6m from that side. It spills out water onto the ground floor's roof. SaveH2O, why do you say slimlines are difficult to clean ? what about their modline tanks that are even squarer at the corners ? Re: Link 2 rainwater tanks some distance apart 10Apr 20, 2013 1:42 pm Hi downtime, Before I give some solutions, a few other notes. Re the slimline tank. The ones that are practically impossible to clean are the 'honeycomb' design. If you have a slimline, it would need a central inlet due to the downpipe's location. I have seen many slimlines with a single top inlet at one end, the outlet connected to the pump directly underneath and the overflow at the opposite end. This means that stirred up sludge during rain is ingested into the pump and the overflow mesh cannot be accessed for cleaning if blocked. Not good! If you decided to have two small diameter but tall round tanks, there would be sufficient room in between for the downpipe and an overflow if needed. There are 1,000 litre tanks with 900mm or less diameters. I have linked a 1,050 litre tank with a 880mm diameter, this tank is not available in Sydney and I have linked it only as an example. Having the additional 4,000 litre tank will negate the lesser capacity plus the 3,000 litre slimline will be expensive and most probably not practical at any rate. http://www.asctanks.com.au/pro-plastics-1050lt-round/ Re the set back. Rainwater tanks are defined as a structure – Class 10b under the Building Code of Australia. What distance is the required set back? Re moving the downpipe. Downpipes are plumbed at the gutter's low point and moving the downpipe means that the slope will also be altered when the gutter is rehung to prevent water pooling. Do you have the option of having two tanks away from the house? This way, the additional tank could match the existing tank. SOLUTIONS Firstly, my company manufactures a unique product that allows you to fill a large tank away from the house to full capacity (no overflow required) and a small tank (overflow required) from the same pipe but fill the small tank last. The device also has an internal 750 micron filter and so it also satisfies the requirement for a mosquito proof leaf diverter. I have linked the web page below but the web page can also be seen on the Homeone website. http://www.supadiverta.com.au/big-tank-small-tank.html http://aquatrek.melbourne.homeone.com.au/ It is manufactured in Australia and it allows numerous downpipes to be harvested but no downpipes are actually diverted. Most of the smaller pressure pipe used is hidden and you would probably use a single 40 mm class 9 pressure pipe to feed the round poly tank. The transfer pipe size is determined by the storage capacity Vs the roof area harvested and rainfall pattern. A class 9 pressure pipe will flow at over 130 lpm with 20 metres of friction loss with a 1 metre head but the head varies with the depth of water in the tank. The emptier the tank - the greater the available head. Your questions are virtually custom written for this product but I can guarantee others reading this that we do not know each other and have had no prior communication. OTHER COMMON SOLUTIONS 1. You could fill both tanks separately but both tanks would require overflows. 2. You could divert a downpipe to the top of the round tank but... A leaf diverter / rainhead will lower the head and you will need a minimum 300 mm head but poly tanks can be buried. There will be an ugly PVC pipe archway between the house and the tank. Plumbing other downpipes to the diverted downpipe is often difficult and ugly. Plumbing additional downpipes often makes the inflow exceed the overflow capacity during heavy rain. 3. You could supply the round tank via a wet system with a vertical riser but... Most vertical risers do not have an adequate flushing velocity to transfer debris up a riser. This can lead to pipe blockages and stagnation. You will need an overflow pipe. It is most often difficult and ugly to divert additional downpipes. 4. Have all of the tanks at the same height and connected with an adequately sized balance pipe but only infeed to the tank(s) at the house. Diverting several downpipes would be difficult unless you had several spaced apart tanks collecting water. The inflow capacity from 4 downpipes to one tank during heavy rain could also exceed the overflow capacity. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. That was always going to be a challenge and a test of patience. Full marks to your mate. Did you discuss the wet area near the trampoline? 16 17409 Found the answer. The recommended distance is .... 1 6030 |