Browse Forums Eco Living Re: Need advice on our rainwater collection and storage syst 2Oct 17, 2012 8:11 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: Need advice on our rainwater collection and storage syst 4Oct 17, 2012 10:13 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: Need advice on our rainwater collection and storage syst 7Oct 18, 2012 4:23 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: Need advice on our rainwater collection and storage syst 9Oct 18, 2012 6:31 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: Need advice on our rainwater collection and storage syst 11Oct 19, 2012 10:22 am 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: Need advice on our rainwater collection and storage syst 13Oct 19, 2012 1:40 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: Need advice on our rainwater collection and storage syst 15Oct 24, 2012 2:49 am HOUSE ROOF CATCHMENT AREA, GUTTER SLOPE & TWO DOWNPIPES The minimum slope for an eaves gutter is 1:500 (2 mm per metre). Water flows slowly along a gutter with the minimum slope and having a more adequate slope would naturally require a greater height variance between the gutter's high and low points. Having the 16 m gutters with two downpipes at each end would mean that the gutters high points (that determines the gutter slope) would be in the middle (at the third post) and 8 metres from both downpipes. This requires a minimum 16 mm height difference between the high and low points (the downpipes location) but more than this would be needed in QLD for good drainage. The other thing is that the roof pitch is subject to a multiplier to determine a factored (greater) roof area to allow for more wind driven rain falling on one side of the roof. In other words, your house roof has to be calculated as a greater area than the 235 sq m plan area. This in turn determines the required gutter cross sectional area and downpipe size. Eaves gutters are required to be designed to handle a 1:20 Average Recurrence Interval (ARI) and the Gympie 1:20 ARI is 230 mm hr. The calculations are based on a 5 minute intensity, i.e. an average of 3.83 mm per minute for 5 minutes. If the roof was flat (no multiplier), each of your house gutters would be required to drain a minimum of 450 litres per minute (117.5 sq m of roof X 3.83 mm of rain per minute). Add the multiplier and each downpipe has to be factored to drain more than this, i.e. during wind driven rain, more rain will fall on one side of the roof than the other. This also affects the wet system pipes. For your area's 1:20 ARI of 230 mm/hr, a 100 mm downpipe fitted to a gutter with a cross section area of 8,000 sq mm is not regulated to drain more than about 36 sq m of (factored) roof area. Your straight gutters are a roof drainage best case scenario but you will need more than 2 downpipes 16 metres apart to prevent gutter overflows. EDITED 18/05/2014. Text tidy up. 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: Need advice on our rainwater collection and storage syst 16Oct 24, 2012 8:36 am AVAILABLE HEAD: I cannot recommend that you have water with the house roof slope factored flow rates diverting through two 100 mm wet system pipes with perhaps less than a 300 mm head to a tank's top inlet with your length of wet system pipe. This is assuming that the roof drainage is properly drained (no gutter overflows) to the horizontal pipes. Sooner or later, you will have a storm that exceeds a 1:20 ARI but the likely available head will struggle with flows less than those generated by a 1:20 ARI. The tanks you have chosen have a good height of flat surface on the bottom wall. There are a few options to safeguard against an insufficient head causing problems during heavy rain and the easiest way is to fit two 50 mm inlet valves about 150 mm above the bottom of tank 4. A 50 mm pipe would branch off each 100 mm wet system pipe and connect to a 50 mm inlet and the two 100 mm wet system pipes would still be fitted with vertical risers to two other tanks, probably tanks 2 & 3. The low restriction inlets will operate with priority flow due to their greater minimum head plus provide low restriction flushing flow paths, ensuring that only clean water is retained in the wet system between rain events. Water will only divert up the vertical risers during times of medium or heavier rainfall and/or when tank 4 is nearly full. It is best to fit a flap valve rather than fixed mosquito proof mesh at the top of the vertical riser. The tank that the garage also diverts to will need a higher overflow capacity TankVac to manage the higher inflow during a storm when the tank is full. The Tankvac overflow system vacuums sediment from across the tank's floor by inducing a syphon. It generates this by restricting the initial discharge of water so that the external overflow pipe is purged of air before it starts operating at high velocity (9 litres per second through an 80 mm DWV overflow pipe). The vacuum break is inside the tank and the vacuum breaks once the top of the overflow pipe inside the tank is exposed, preventing the tank from syphoning dry. TANKS: I always recommend having a settling tank system. The above scenario allows tank 1 to supply the house with decanted water transferred from tanks 2 & 3. Dry system pipes from the garage will need vertical supports and this will be ugly. I would merge the pipes at the garage into a single 100 mm wet system pipe with a vertical riser to eliminate the ugly pipe arches. I would also fit a first flush diverter at the garage and a sediment trap at the base of the vertical riser. Balance lines between the tanks would be fitted 100 mm or so above the bottom of the tank at the valve's lowest point. A device like a Waterboy could be fitted internally to low plumbed balance line outlets between tanks 3 & 4 but the balance lines between 3-2 and 2-1 would not need a Waterboy as the water will be clean but fitting one between tanks 1-2 would provide the very best of the decanted water. The balance lines only need to be LDPE 25 mm poly pipe connecting to 1" valves. I would also fit a DIY sediment trap to both 100 mm horizontal pipe. For a 100 mm DWV pipe, you buy and fit the following... (copied from another thread on this forum) One 100 mm 45 degree plain junction F+F. Fit this with the branch on the underside. Connect one 100 mm 45 degree plain bend M+F to the branch. Connect one 100 - 50 mm level invert taper to the elbow. Connect one 50 - 40 mm level invert taper to the larger taper. Once fitted, you connect the taper to 40 mm DWV pipe. There are then a couple of fitting options for draining the 40 mm pipe and by using the smaller pipe, the water can be regularly part flushed with less wastage. The higher velocity discharge through the small pipe also self cleans that pipe. Most of the debris will simply drop down into the elbow and will substantially reduce the amount of sediment in the tank and greatly improve water quality. There are several ways that the sediment trap can be made from off the shelf parts. Don't use the leaf catcher. EDITED on 18/05/2014. Reason: Explanation tidy up. 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: Need advice on our rainwater collection and storage syst 17Oct 24, 2012 3:07 pm Following this thread with interest as I am at the same point of making water tank connection decisions. I understand the reasonings behind having a wet system enter the tank at a low point (to reduce the disturbance of the settled crud in the bottom of the tank, aerate the anaerobic zone and to increase the available head) however this means the wet system is fully charged at all times once the water level reaches the inlet height. Granted this makes flushing the system easier as the head in the tank assists with the flushing power. @SaveH20 - Is there an upper limit of tank size before the water pressure exceeds the burst pressure (of joints more likely) of 100mm DWV? I am looking at a single 200KL Rhino tank due to available space and budget restrictions. ie 2x100KL wont fit and are $7000 more than the single 200KL tank. The two issues I have with a low point connected wet system is a) failure of the joints in the 100mm DWV sections. If my 200KL tank is full and the pipe burst or joint failed, I will have 150KL+ worth of flooding! plus the loss of all that precious water. b) the lack of ability to place a first flush device into a fully charged wet system. In my opinion a wet system must have a first flush device fitted just prior to the tank inlet. In times of low/nil flow, the water in underground 100mm components could be very stagnant. However I am unable to envisage how you could do that and still have a fully charged system under tank pressure. Regards RiH Re: Need advice on our rainwater collection and storage syst 18Oct 24, 2012 6:22 pm Awesome, SaveH2O! I'm no buff when it comes to the Australian Standards, but surely it ought to also mention the area the gutters "service"? I mean, 100 square meters fed into 10 meters of gutter is quite different than 12.5 square meters fed into 10 meters of gutter. With that said, I will make a compromise on my own build: I'll have square downpipes to match the house, knowing full well they're not as effective as round downpipes. They'll be big, though - I'm thinking 200x300 mm, so two or three of them should be alright for a total catchment area of 130-140 square meters (the roof is almost flat, angled backwarks, so it will run to the back of the house into a single, integrated (hidden) gutter). Re: Need advice on our rainwater collection and storage syst 19Oct 24, 2012 7:33 pm Crikey, a lot to digest there. It's a steep learning curve for me and is certainly a crash course in rain harvesting. Thanks SaveH20, your time in freely giving advice on here is commendable. I'll do some study on the above and reply again with some questions. One thing I haven't been able to get my head around is using the low inlets in the side of the tank. If the tank is even say half full (12,000 litres) wouldn't the pressure of that volume of water prevent any water entering from the wet system? The other thing I'm wondering about is what type of fitting should be used for a low inlet especially considering the Camel tanks have a corrugated side wall profile. I'll check with Camel but they're don't seem to like discussing anything 'out of the box'. Will also check with them re warranty in regards to cutting holes in the sidewall. John P.S. The house kit company has now agreed to supply 3x 100mm downpipes for each of the two awning gutters. Re: Need advice on our rainwater collection and storage syst 20Oct 24, 2012 10:22 pm Great work there SaveH20 (AKA...). I have read your description of the low tank inlet and sediment trap elsewhere and plan to include it in our current build. I had the same query as Rocks regarding pressure/vulnerability of joints and seals and pipes including risk of damage to the inflow pipe leading to backwards loss of water from the tank. Once you know the basics, the rest is easy. Read my post in the thread linked below. viewtopic.php?p=1919271#p1919271 2 19880 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 8656 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 31468 |