Browse Forums Eco Living 1 Jun 16, 2022 5:16 pm Hi, I am building a new house in Perth and I am after some advice on how to best install the rainwater collection system. I have read a few of the posts in this forum and also up on the Supadiverta product, and wonder if this would be suitable for my purpose. I have attached a plan of our house (with unnecessary details removed) to give an idea of roof design and downpipe/tank locations. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ It is a simple roof design with the larger section supplying the tank. My main concern is that the gutter and 2 downpipes draining each roof section will be enough. I have listed the area roof area and rainfall stats below. I plan on installing a ~3000L tank to supply the 2 toilets and washing machine. This would be supplemented by mains water, using a device such as the Acquasaver or similar. I will have a pump assisted by a pressure tank. I plan on having a floating outlet to access cleaner water from the tank. Purpose: Toilet and washing machine supply only Tank: 2000-3000L slimline, ~1800mm high Gutter height: ~3.1m Catchment: ~140sqm Annual rainfall: ~730mm AEP (5%, 5min): 131mm/hr I like the Supadiverta for the following reasons: 1. The first flush system makes more sense than what is normally used 2. No need for tank overflow if fitted at the correct height My main questions are: 1) Given the tank is almost right under the downpipe will a dry system be better, or am I still better off installing a wet system? (The water will only be used for toilets and washing machine, and I will have a floating outlet, I don’t think a Supadiverta style sediment trap is necessary) The smaller section of roof is currently planned to drain straight to the soak wells. Is it possible connect a Supadiverta straight onto drip irrigation line into the garden? Or does it still need to drain into a tank and then the drip line is supplied from the tank by a pump? Thanks in advance for any help. Cheers, Wynand Re: Rainwater Collection Perth 2Jun 18, 2022 3:05 pm Hi Wynand and welcome to the forum. I have a question first up regarding the 6 DPs and their location. Why they are grouped in pairs and is this the finalised roof drainage plan? 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 Perth 3Jun 20, 2022 2:34 pm Hi SaveH2O, Regarding the downpipes, I'm not sure. This is just how the architect has designed them. This doesn't necessarily have to be final drainage plan if you think there is a better way to do it. Any advice would be much appreciated. Cheers, Wynand Re: Rainwater Collection Perth 4Jun 20, 2022 10:52 pm Hinderwell.House My main concern is that the gutter and 2 downpipes draining each roof section will be enough. Regarding the downpipes, I'm not sure. This is just how the architect has designed them. Do you mean will be enough to drain the roof areas or to supply the tank? I have the same question for the former. Having downpipes paired is shall we say strange and it concerns me. Even though I don't know the gutter and downpipe size, I have serious doubts as to the intent being compliant. Why is the architect designing roof drainage? Hinderwell.House I like the Supadiverta for the following reasons: 1. The first flush system makes more sense than what is normally used 2. No need for tank overflow if fitted at the correct height Yes, a manually emptying first flush diversion system is much better than the usual dripper ones that waste a lot of water. Re the overflow, a bit of detail that should also help others understand a common non adherence to compliance is below. Your 131mm/h 1:20 ARI is based on an average of 2.18 mm/minute over a 5 minute duration but this figure is the minimum qualifying figure. If you picture a ruler with the 1:20 figure on it and further along you have the higher 1:50 ARI figure, you could be experiencing a rain intensity that is just below qualifying as a 1:50 ARI but well above the 1:20 ARI qualifying intensity yet still in the 1:20 ARI classification if that makes sense. This is why I always advise people to design for more than the minimum qualifying figure. Regardless and for this next example, I will use the minimum 1:20 ARI figures to also show another reason why fitting a Supadiverta to eliminate the overflow pipe is a good idea in addition to aesthetics and cost savings. The 6 degree roof slope has a slope factor of 1.05 to account for wind driven rain, making the 140 sq m roof area 147 sq m. 147 x 2.18 = 320.5 litres of rain per minute that will fall on the larger roof area during a minimum qualifying 1:20 ARI. Assuming that your slimline tank has a flat roof, the tank manufacturer will almost certainly fit a 90mm overflow outlet to the very top of the wall as they all invariably do. See photo. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ It will depend on the style of slimline tank as to whether you can fit a 100mm overflow outlet but a 90mm overflow pipe just won't cut it. A 100mm outlet with 100mm of water above the invert will flow at 4.67 lps (280.2 lpm) as per AS 3500.1 BUT this is the flow rate through an unmeshed outlet! You can however remove the mesh and fit an Air Gap made by Rainharvesting to the external overflow pipe which will improve the discharge rate by about 20% but the increased discharge rate will still be inadequate plus the tank will have no mitigation capacity. Strangely, the manufacturer strangely doesn't also promote the Air Gap as a device that will increase a tank's overflow capacity. https://rainharvesting.com.au/products/ ... y/air-gap/ The easiest way to further increase the overflow capacity is to have a greater height of water above the outlet's invert which will also provide a mitigation capacity. A water surface height of 125mm above the invert will give a discharge flow rate of 5.72 lps which is 343.2 lpm. This is less than the bare minimum I would recommend but you will also sacrifice +125mm of storage capacity. Height adjusting Supadivertas to eliminate the need to have a water tank's overflow pipe as well as improve aesthetics, save money and increase the tank's storage capacity is best practice. Additional to this are the dual downpipes...if these were somehow passed as compliant, the first downpipe would harvest too much water during even moderate rain to be able to use a Supadiverta efficiently. I suggest having three spaced 90mm round pvc downpipes, Hinderwell.House I plan on installing a ~3000L tank to supply the 2 toilets and washing machine. This would be supplemented by mains water, using a device such as the Acquasaver or similar. I will have a pump assisted by a pressure tank. I plan on having a floating outlet to access cleaner water from the tank. All good ideas. The hydraulically operated Acquasaver does not use power, is bullet proof and can be used with a pressure tank, unlike some other automatic mains water switching devices. You also have the option of fitting a much cheaper manual change over device and unlike automatic devices that are plumbed into the house mains water line which requires a check valve, a manual system can use its own separate pipe to connect to the end fixtures. Very few new home owners are informed of this option. A pex pipe would be plumbed from the pump to connect to the toilet cisterns and a separate rainwater cold water tap in the laundry. The toilet cisterns will need two cistern valves, the compact Fluidmaster 400UK063 is the popular choice as it has a float that moves up and down the shaft. Just remove the plastic pigs tail fitting from the bottom of the shaft before fitting. There will now be two isolation valves on the wall, one for mains water and one for rainwater. The valves are your manual change over devices. The cistern valves air gaps will serve for backflow prevention and there is no need to go outside to open and close valves should the tank run out of water. You will also save $$$. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Most if not all of the current floating intake filters have problems that people are not aware of but I have designed an improved version that also has finer filtration (the target is 200 micron) plus it will be much cheaper due to better design principles. It should be available early October when our new website is launched. Hinderwell.House Gutter height: ~3.1m Catchment: ~140sqm Annual rainfall: ~730mm AEP (5%, 5min): 131mm/hr You usually work on a best case 85% yield. Your annual 85% yield comes to a long term average of 87,400 L per annum which is an average of 1,680 litres per week but of course your rainfall pattern and tank size will see your tank full during your wet periods and not all water usable at times. You will have a much larger annual rainwater harvest than all but a few % of other persons who are also on mains water. Your gutter height will present no fitting problems and I can advise on pipe and inlet valve sizes once you know the downpipe locations. The carrier pipe at the head of the system is sized so that sediments are flushed and the pipe is upsized at each subsequent downpipe. Hinderwell.House 1) Given the tank is almost right under the downpipe will a dry system be better, or am I still better off installing a wet system? (The water will only be used for toilets and washing machine, and I will have a floating outlet, I don’t think a Supadiverta style sediment trap is necessary) A dry system requires a downpipe. A surprising amount of small grit still manages to make its way past the Supadiverta 750 micron filter despite its steep slope although more than half of this is usually captured by the first flush outlet because the fitting's opening is below floor level and captures sediment that falls to the floor throughout the entire rain event. The sediment trap is inexpensive and because the discharge pipe is size reduced, it drains with high velocity with little loss of water. If the trap is fitted, all that enters the tank is very fine suspended matter that resembles talcum powder when it dries. It is nothing like the usual sludge. The main reason people complain about dirty water in their toilet cisterns and why they won't wash their clothes in "dirty" rainwater is because water dropping into a tank from above the tank resuspends sediment, making the water turbid. The top meshed basket is also often fitted above the outlet that supplies the pump plus that outlet valve is usually fitted too low and draws the worst quality water in the tank. When pre-filtered water is transferred from a Supadiverta into a tank via a low restriction inlet fitted 100mm or so above the bottom of the tank, the lower density water quickly de-energises and rises upwards. Hinderwell.House Is it possible connect a Supadiverta straight onto drip irrigation line into the garden? You can connect a Supadiverta directly to drip hoses etc but fitting an inline tap is a must. You can also fit inline filters to the drip irrigation. 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 Perth 5Oct 19, 2022 10:52 am Hi SaveH2O, Thanks for the very informative reply. Sorry I didn't get back to you earlier, we've had some time away. They build is progressing well with the roof sheeting is being installed this week. Regarding the downpipes, these were drawn by the architect for illustrative purposes and don't necessarily represent the final locations. I will speak to the roof plumber soon about final locations and size of downpipes to ensure they are adequate for the roof area. I will update the forum drawings/information once I have the final details. When height adjusting the SupaDiverta to eliminate the tank overflow, at what height relative to the top of the tank do you install the SupaDiverta? I will definitely be keen to use you new floating intake, are you close to releasing this product? Also, how is it going with the planned website upgrade? Many thanks, Wynand 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 31327 Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 19557 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 8449 |