Browse Forums Eco Living 1 May 26, 2013 4:24 pm Hello all I would like to start a rainwater tank project, first starting small and expanding later as money and time permit. I want to start with a 5000L and add extra tanks later. I will use the water for watering Citrus plants and maybe other parts of the garden and possibly the toilet. The area I have picked out is 3x8m between the fence and the house so should accommodate two or three tanks. I have connected the patio down pipes together and routed the water to the end of the property where I would like to place the tanks. Here is where I have run into an issue, how do I connect the first flush/leaf strainer, I could run the pipe straight back, but it would be at head height. Or I could tunnel some 100mm pressure pipe under the concrete and have a wet system, but I don't think there is enough head between the first flush device and the entry into the top of tank. I have read from forum posts that I can connect the wet system at the base of the tank but that would require a valve, and that that size they would be pricey plus all that manual labour trying to get a pipe that size under concrete. For overflow I will use 100mm pipe through the back fence to the street. Can anyone give any alternatives that I haven't thought of? I will post some pictures of the area. Thank you in advance. Pictures https://www.dropbox.com/sc/zc8i9znol48pko4/NaQL1wtvWp?n=100203914 Re: Rainwater tank connection conundrum 2May 26, 2013 4:43 pm With a wet system you don't have to make the connection at the bottom or the top anywhere between those points is fine. Connect just below the overflow level and you won't need a valve. 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 connection conundrum 3May 26, 2013 4:51 pm bashworth With a wet system you don't have to make the connection at the bottom or the top anywhere between those points is fine. Connect just below the overflow level and you won't need a valve. I was thinking I needed a valve so I could shut off the tank when servicing the we system, otherwise I would loose all the tank water when I opened the inspection cover. Re: Rainwater tank connection conundrum 4May 26, 2013 5:46 pm If you connect just below the top water level like the sketch here (http://www.anewhouse.com.au/?p=5115) you only lose the water in the pipe, and a little from the tank ONLY IF the the tank is completly full 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 connection conundrum 5May 26, 2013 6:19 pm What area are you in? I need it for your 1:20 ARI, rainfall pattern and hydraulic calculations. It looks like S.A. Will you only harvest off the rear pergola roof? What is the sq m size of this roof. Is there a storm water connection where the downpipe drops to the ground? I take it that the 3 x 8 metre area intended for the tank(s) is the area shown in photo 4 with the square concrete stepping blocks. Are you planning to do anything to this area as a tank base? I also notice two windows in photo 4. Have you considered the possible effect that the tank's height could have on the natural light that currently transfers through these windows? Given the dimensions of the area, have you considered a large diameter squat tank? This would also solve the (probable) head issue. Unless you cut through some concrete, you would have to lay the feed pipes above ground. Feeding through a low inlet allows the wet system pipes to flush every times it rains as well as providing greater head. The method operates with a variable head; the lower the water in the tank - the greater the head feeding to the tank - the higher the potential flow rate. The hydraulic calculations need to be factored for a full tank during a major storm. You usually do not need a big inlet valve. You can also divert a wet system pipe to the tanks top meshed inlet AND have a smaller (reduced) pipe coming off a tee that also supplies the riser provided that a leaf diverter is fitted at the downpipe. The smaller pipe would feed into a smaller valve about 100 mm above the bottom of the tank. The small infeed pipe operates with greater head than the normal wet system transfer and so it will provide most of the infeed during normal rain but importantly will also supplement the wet systems infeed during heavier rain. A 25 mm pipe and valve is often used. Leaf diverters on wet systems are compulsory in many areas and a good idea regardless. You would have to fit one to the pole and pack it out. It is also a requirement that water has to pass through mosquito proof mesh before entering a storage tank. Have you a tank in mind and do you know how high the inflow pipe will be at its centre point above the top meshed inlet? 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 connection conundrum 6May 26, 2013 9:58 pm Hi SaveH2O, Sorry for the late reply, I went for a bit of a nanna nap. SaveH2O What area are you in? I need it for your 1:20 ARI, rainfall pattern and hydraulic calculations. It looks like S.A. Will you only harvest off the rear pergola roof? What is the sq m size of this roof. I'm in Perth, here is a link to the ARI calculation from the BOM website. https://www.dropbox.com/s/svq4nzd6vq92ass/Capture.JPG I will collecting off the patio mostly but there is one diversion pipe from one section of the rear of the house that diverts onto the patio. If I did my calculations right, the area should be 73.85m2. The red dots will be collected. Yellow is existing house downpipes Green is a downpipe that goes straight into the garden The blue dot is the diversion from the house to the patio. Not sure how well it flows. https://www.dropbox.com/s/2p8t3e5nrzxsxqn/house.JPG https://www.dropbox.com/s/ervz01k7zib1dlg/2013-05-26%2012.24.29.jpg SaveH2O Is there a storm water connection where the downpipe drops to the ground? No, just falls on to the sandy part of the lawn, it drains away within seconds. SaveH2O I take it that the 3 x 8 metre area intended for the tank(s) is the area shown in photo 4 with the square concrete stepping blocks. Are you planning to do anything to this area as a tank base? I hadn't planned on it, those are concrete slabs on sand with gravel between them, thinking about it now 10,000 litres is 10 ton. Any suggestions in this area? SaveH2O I also notice two windows in photo 4. Have you considered the possible effect that the tank's height could have on the natural light that currently transfers through these windows? Given the dimensions of the area, have you considered a large diameter squat tank? This would also solve the (probable) head issue. I had thought about it, one room is my study the other is a junk room, It's just me I'm not overly fussed about those rooms. I have a company coming out Saturday, I will ask him if he does squat tanks. SaveH2O Unless you cut through some concrete, you would have to lay the feed pipes above ground. That's what I thought, at least my soil is sand, I should be able to water jet under it. SaveH2O Feeding through a low inlet allows the wet system pipes to flush every times it rains as well as providing greater head. The method operates with a variable head; the lower the water in the tank - the greater the head feeding to the tank - the higher the potential flow rate. The hydraulic calculations need to be factored for a full tank during a major storm. You usually do not need a big inlet valve. You can also divert a wet system pipe to the tanks top meshed inlet AND have a smaller (reduced) pipe coming off a tee that also supplies the riser provided that a leaf diverter is fitted at the downpipe. The smaller pipe would feed into a smaller valve about 100 mm above the bottom of the tank. The small infeed pipe operates with greater head than the normal wet system transfer and so it will provide most of the infeed during normal rain but importantly will also supplement the wet systems infeed during heavier rain. A 25 mm pipe and valve is often used. Good idea, the tank I'm looking at has a 25mm base outlet and a 20mm tap outlet at 500mm, maybe I can use one of those. SaveH2O Leaf diverters on wet systems are compulsory in many areas and a good idea regardless. You would have to fit one to the pole and pack it out. It is also a requirement that water has to pass through mosquito proof mesh before entering a storage tank. Have you a tank in mind and do you know how high the inflow pipe will be at its centre point above the top meshed inlet? I have a superhead leaf diverter/first flush. http://superwall.com.au/products/superhead/ The top screen is large enough for a mosquito, but not sure about the "bottle brush" filter, what's the smallest mosquito's can get through? Here's one that's coming out Saturday to quote, I was looking at the 5000. http://jojotanks.com.au/Poly-Watertanks# Re: Rainwater tank connection conundrum 7May 27, 2013 12:10 pm Thanks for the info. I had it picked as S.A. with W.A. the second choice. The 74 sq m roof area will collect 172 lpm during a 1:20 ARI. I always design for a 1:20 ARI plus an allowance but this is not regulated (although it should be). The (blue dot) spreader will divert a reasonable amount of additional water to the harvested roof area as it is between the roof valley and the (yellow dot) downpipe at the corner near where the tanks are going. The downpipe is the low point and the valley will (or should) be draining to the Gutter's high point. The water from the valley will drain freely to the patio roof spreader as the second (yellow) downpipe on the opposite side of the house is 9 metres away from the valley and there is also a corner that adds resistance to the flow. It’s a bit hard to work out just how much extra water it would divert to the patio roof during a 1:20 ARI but I am guesstimating about 30 lpm (202 lpm in total). However, other flow calculations show that the slotted gutter will overflow through the slots prior to a 1:20 ARI and so the flow to the tank(s) would be less than 202 lpm. The bottom of the 100 mm horizontal pipe running under the patio gutter appears to be about 2.2 metres high. Unfortunately, the 5,000 litre tank being considered is 2.16 m high and you need head pressure. This means one of two things... 1.) You need a shorter tank. 2.) You could partially bury a poly tank. I often part bury a poly tank in a compacted sand base but I generally only go down 80 mm because of the valves. You would need to go down more than this plus it also means having a submersible pump. You first need to work out the respective levels before you do anything else. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. 18 90484 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 31157 |