Browse Forums Eco Living Re: Project home builders and Rainwater tanks 4Nov 24, 2013 12:16 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: Project home builders and Rainwater tanks 5Nov 25, 2013 5:38 am SaveH2O -- you are an absolute legend. It does sound like what I'm asking for maybe a bit overkill given where we are (rainfall wise). And thank you for the sage advice about hooking up the water to the HWS post build. That will I assume halve the chlorine for baths/showers. In any case if we're doing that post build it gives us time to think about things. Sounds like there is a fair amount to think about! My husband has a weather station so we'll check on the rainfall patterns although this year has been very strange!! Thanks again SaveH2O for the very comprehensive response. I'll be re-reading it again and again. Re: Project home builders and Rainwater tanks 6Nov 25, 2013 1:46 pm Thanks! Yes, your weather certainly has been strange with quite a lengthy period with little rain. An extra note... When you calculate the roof area harvested, you do so by calculating the roof plan area that drains to each downpipe. Gutters are sloped so that they drain to a low point and the minimum slope for an eaves gutter is 1:500 (2 mm per metre). The downpipes are fitted to the gutter's lowest point and the gutter's highest point between each downpipe determines the flow to each downpipe and the roof area that each downpipe harvests. On established houses, the gutter's high point can often be judged by observing the gap difference between the bottom of the gutter and a design line along a metal fascia if applicable. There is often a seam at this point. When all else fails, you can simply pour some water in the gutter and see where it flows. Downpipes are most often shown on house plans as nominal positions for aesthetics. This is why display homes often don't have downpipes at the front and are positioned at the end of walls rather than closest to the largest roof areas. Sometimes the drainage is redesigned on site for greater efficiency but this is not usual. If you want to calculate the roof drainage areas off the house plan, it needs to be established as to where the downpipes will actually be fitted and where the gutter high points are. The downpipes will drain different size areas of roof and once you know the roof area drained, you need to deduct a % to allow for evaporation. An 85% yield is very good for Melbourne (where we do field testing) as over a third of all rain days have falls of 2 mm or less and intermittent summer showers produce little run off. First Flush devices further reduce yield and first flush devices with drippers can decimate it. I don't have any long term research data for Sydney but given your different rainfall pattern (a lot less drizzle and less short duration showers), I would expect your yield loss to be less than Melbourne. Nevertheless, I would still use 85% yield for your calculations even though it may be a few % better. 1 mm of rain on 1 sq m = 1 litre. If you use a round figure of 1,200 mm annual rainfall (there is no telling what you will actually get from one year to another) and you harvest 100 sq m of roof, we get 1,200 X 100 X .85 = 102,000 litres, an average of 279 litres per day. The Sydney average daily mains water use per person per day for 2012-2013 was a historical low of 310 litres (more than double Melbourne with 149 litres so there is plenty of room for improvement)! http://www.sydneywater.com.au/web/group ... y%20use%22 As you can see, harvesting 100 sq m of roof in Sydney will provide less than the average daily use for 1 person. This would be sufficient if only the toilets and laundry were supplied. You could prioritise use to the HWS by switching the toilets to mains water. While there are no regulations stating such, a rainwater harvesting system should be designed to accommodate the same rainfall intensity that the house gutters must drain (as a minimum) during a 1:20 ARI for eaves gutters and 1:100 ARI for box gutters. Your area's 1:20 ARI (if you have eaves gutters) is likely to be about 180 mm/hr, based on a 5 minute intensity of a 3 mm average per minute. If the tank fills during a 1:20 ARI (that happen a lot more frequently than every 20 years), the tank's overflow pipe must cope to prevent the tank over topping. If you ask a plumber what the flow capacity of a tank's 90 mm or 100 mm overflow pipe is, they will not know. If you ask them what the overflow's mesh open area % is, they will not know. If you ask them what the reduction in flow rate is that is caused by the mesh, they will not know. If the client is harvesting 100 sq m during a 1:20 ARI of 3 mm/min or 300 litres per minute, the system should be designed so that the overflow will cope. For your system, you should harvest the greatest roof area possible but have a system that will not compromise the overflow capacity during a storm. You also need to make sure that the stormwater pipe supplying a wet system (& vertical riser) is flowing within its regulatory capacity. All this will be down the track and is easy to design. Done properly, the system will be productive, efficient, neater and cheaper! BASIX could require a 5,000 litre tank. If possible, try to have more as 5,000 L won't last long during a dry spell. It is good if you can have a large tank away from the house for aesthetic reasons and a smaller tank (but the same height) near the house but a tank doesn't always have to be sited next to the house. 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 17412 Hi all, Been browsing project builders' website and saw Masterton with attached granny flat design Seeing bad reviews from masterton in this website/facebook, does… 0 18418 |