Browse Forums Eco Living 1 Nov 22, 2013 11:42 am Hi I see there are some experts here so hoping for some help. We're looking at possibly a project home build with Sekisui and as part of Basix it is assumed we'll get a rainwater tank and they will hook it up to laundry and the toilets. However we're wondering if we can hook it up to supply all the bathroom water. I rather shower in rainwater than town water (ie I don't like chlorine if I can help it!). What's the likelihood of us being able to do that with a project home builder? I've put in a request... Anyone have any experience with 'odd' requests like this with a volume/project home builder? I've also asked about a grey water system quote too but wondering if I should be just requesting the plumbing to cater for it and then hook it up later? Thanks in advance. Re: Project home builders and Rainwater tanks 2Nov 22, 2013 2:58 pm I'll be interested to see the answer from someone who knows. I suspect the answer is a big "no" because our taps in the garden have a warning not to drink the water because it is from a tank.!! I was brought up on a farm....all we had was tank water...and now its unfit for human consumption ? go figure. Re: Project home builders and Rainwater tanks 3Nov 22, 2013 3:10 pm Ill be surprised if they said no. We are building with a volume builder on semi rural land with no towns water connection, a rainwater tank will supply all our water. Re: Project home builders and Rainwater tanks 4Nov 24, 2013 12:16 pm yvonneh I've also asked about a grey water system quote too but wondering if I should be just requesting the plumbing to cater for it and then hook it up later? Going by your profile, you are close to Sydney. Sydney has an average annual rainfall of around 1,200 mm. Grey water blocks drip hoses and must be used within 24 hrs if stored. It is good if you can fit a simple 2 way divert valve on an outside laundry pipe to catch the washing machine's final rinse but with the front loaders, this is not always worth the trouble, particularly if you live in an area that (usually) has high consistent rainfall. yvonneh We're looking at possibly a project home build with Sekisui and as part of Basix it is assumed we'll get a rainwater tank and they will hook it up to laundry and the toilets. However we're wondering if we can hook it up to supply all the bathroom water. I rather shower in rainwater than town water (ie I don't like chlorine if I can help it!). What's the likelihood of us being able to do that with a project home builder? There are things that you need to know and consider that go beyond your simple question and its peripheral consequences, for example, the increased roof area harvesting needs and the resultant tank overflow limitations when the inflow exceeds the tank's overflow capacity during heavy rain, required storage capacity, pre and post tank filtering, pump stop/start management considerations, the most appropriate and best value mains water switching device etc. When water tanks are connected to cisterns and the laundry by plumbing into the mains water pipes, check valves are required to prevent the possibility of cross contamination between potable mains water and stored harvested waterif the mains water line ever developed negative pressure, during maintenance for example. AS/NZS 3500.1:2003 Section 4 specifies the requirements and methods for the prevention and contamination of the drinking water within the water service and the main water and provides for the selection and installation of back flow prevention devices. 4.2.2 also states: Quality of water supply Only drinking water shall be supplied to plumbing fixtures or outlets for human consumption, bathing, food preparation or utensil washing. The New Zealand Building Code does not require the supply of drinking water for bathing. Having noted the above, it must also be noted that many houses connected to mains water Australia wide also have water tanks connected to the HWS to fully utilise their rainwater harvesting system. I remember a couple of years ago that a circular was released in QLD stating that it was now ok for Queenslanders to plumb their water tank to the HWS in that State. This is common sense overriding regulation but it would be best if there were applicable regulations regardless. Amazingly, BASIX disregards the Standards and allow "whole of house" connection. http://www.basix.nsw.gov.au/basixcms/ba ... r-use.html This is crazy as most suburban water tank installations are sub standard (but often compliant) and do not deliver potable water. If your installation is well set up and delivers good quality sediment free water and if the HWS is close to the pump, you could ask to have the pump plumbed to the HWS. Using rainwater in the HWS will give you better quality shower water and greater utilisation but you will most probably need additional storage capacity. With a high percentage of water tank installations being sub standard yet often still compliant, you will need to instruct the builder as to how you want the installation optioned and plumbed. His installer/plumber is highly unlikely to know best practice. I can give that advice and a good installation won't cost much more in most instances. A well set up rainwater harvesting system will deliver good quality water to the tank and the best quality water in the tank then delivered to the pump. I always recommend having a settling tank system. You should have at least a 10 micron cartridge filter or similar after the pump to filter free floating solids. If the tank delivers good quality water, the filter will have an easy life. Just make sure that the filter is not exposed to sunlight, yet another mistake that I see all too often! Many are UV stabilised but it is still not a good idea. You will also need to harvest as much roof area as possible without compromising the tank's overflow capacity. This can either be done by fitting a high flow capacity TankVac syphonic overflow system http://www.youtube.com/watch?v=e1_B9WITe94 that vacuums the sediment layer and syphons water from the anaerobic zone when discharging and/or fit a product I invented that can stop the inflow once the tank fills, thereby even eliminating the need for an overflow pipe! This also saves money, particularly when siting tanks away from the house plus it allows numerous downpipes to be harvested without fear of the tank over topping. Read the thread below re problems with the water tank's overflow capacity! This is not uncommon. viewtopic.php?f=35&t=68234 You need to consider the onsite storage capacity when you have greater utilisation. The Alternative Technology Association (ATA) have the "Tankulator" site that you can play around with. There are many different shaped tanks and they can all be linked provided the ground levels are accommodating. If you are having a pool, have a look at the tanks in the link below... http://www.landscapetanks.com.au/ The best rainwater harvesting systems use leaf diverters. Also use sediment traps if you have a wet system. Wet systems lack the velocity to flush detritus from the pipe up the vertical riser unless there is very heavy rain. I have seen many wet systems block up and/or become stagnant and rectification made difficult because the pipes run under paths, paving, concrete and gardens. Just about all wet systems installed are sub standard but there are simple methods that I have developed that eliminate the usual problems. I can post advice if needed. First Flush Diverters (FFD) need their own section. There are also numerous FFDs fitted by industry 'experts' to the top of wet system vertical risers. Wet systems retain water in the pipe to the level of the top of the riser (or the FFD if fitted to the riser) and FFDs fitted as described simply fill with the settled water in the riser while the first flush is still in the downpipe at the other end of the pipe the next time it rains!!! Amazing, for further information, BASIX links a Government website for "Comprehensive technical guidance on rainwater tanks" from www.yourhome.gov.au http://www.basix.nsw.gov.au/basixcms/ba ... water.html http://www.yourhome.gov.au/water/rainwater shows a diagram of the above described and useless standard FFD position (along with other poor advice) on their website as an example of how to plumb a tank. Do you laugh or cry? PLUMBING THE PUMP TO THE HOUSE NSW is notorious for builders and plumbers telling new home owners that they must have an expensive automatic mains water switching device fitted when connecting a water tank to the toilet. This is simply not true! These devices can be ugly when mounted to walls. Many plumbers simply do not know the regulations and lack industry knowledge of best practice. The Plumbing Code of Australia 2008 states: "PART 7—REQUIREMENTS FOR WATER SUPPLY WORK 10 Definitions In this Part— automatic or manual interchange device means a device that by way of manual or automatic means can alternate between varying water sources; Requirements where rainwater used for sanitary flushing. (1) If a reticulated water supply from a network utility operator is connected, or proposed to be connected to a building where a rainwater tank is installed for the purpose of sanitary flushing, an automatic or manual interchange device that allows alternate use of water from the rainwater tank or the reticulated water supply must be installed to ensure that there is a continual supply of water for sanitary flushing”. BASIX does not specify the use of an automatic mains water switching device; they refer users to the relevant plumbing codes and also to the water utility for their guidelines. Given your location (rainfall pattern) and if you harvest a sufficient roof area and have a decent storage capacity, I suggest that you plumb AUSPEX pipe to the HWS, separate cold water tap in the laundry and to a second cistern valve in each cistern. The water tank supply is turned off at the cistern's isolation valve on the wall and the mains water cistern isolation valve opened whenever the tank storage level gets low. The twin cistern valve system qualifies as a manual interchange device and is discussed in the thread below. viewtopic.php?p=1093366#p1093366 For your proposed installation, you could also fit an automatic tank top up device like the one linked below. This will prevent the water tank from emptying and would rarely be in use if the harvesting system was correctly sized. It tops up the tank's water level by 100 mm once a set low level is reached. The set low level is above the level where the pump would cease to draw water. http://www.apexvalves.co.nz/plumbing/apex/rainaid.html Sydney Water mandates that a 2 lpm unit must be fitted. This means that when the tank is low, you won't be able to use it for lengthy garden watering. You will soon get to know how much water you have in storage and you will also become expert at looking at the BOM radar. http://www.bom.gov.au/products/IDR714.loop.shtml#skip You also have to consider the pump. If you get a submersible pump, make sure that it is not placed directly onto the tank's floor as it will vacuum the floor of sediment and draw the worst quality water from the anaerobic zone. It will also void most manufacturers warranties. Most submersible pumps that I see are not fitted as per the manufacturers instructions or best practice. The pump will have a lot of use and it would be worthwhile looking at a Grundfos variable speed pump. These have a 'soft' start and are energy efficient. They are pricey though. You could also consider having a large pressure tank, a minimum of 35 litres. These save a lot of pump start/stops (wear & tear) and a larger tank has less pressure fluctuation, important when having a shower. The pump's pressure switch setting MUST be compatible with the tank's pressure setting. By using a suitable pressure tank,you could easily save 80% of the pump use and the pump will always operate in its sweet spot rather than be strangled (as most pumps are) when supplying low flow demand fixtures, cisterns for example. http://irrigationrepair.com/how_pressur ... _work.html EDITED 05/06/2014: Additional information. 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 18546 That's brilliant would appreciate if you have you can locate the other doc so I can use it with my discussion with the building surveyor 10 2523 |