Browse Forums Building A New House 1 Apr 22, 2013 9:40 pm . Block settled 07 June 2011 Our little piece of the Interwebs on HomeOne....... viewtopic.php?f=31&t=48577&start=0 Re: 22,000 l Rain Tank......Best way to use it 3Apr 23, 2013 11:45 am Pepsi_Drinker I was able to have a really long and informative talk with the plumber, I thought he seemed really down-to-earth and honest and didn't feel rushed or like he was trying to sell me anything I didn't need. I had planned to have the rainwater plumbed to all the toilets and washing machine, but he had a radically different idea !! His suggestion was to plumb the WHOLE house to the rainwater tank EXCEPT the toilets and garden taps ! His logic in not connecting the toilets was that they're used quite a few times a day, but only for 3 - 6 litres at a time so not much point running the pump so much for so little benefit ! You have posted in the wrong sub forum, your thread will quickly get lost in this one. You have also talked to a very unusual plumber...one who has given his time and who thinks and gives a considered opinion. There is a lot of merit in what he says. You have obviously done some other investigation but I will go over the steps that you need to take. RAINFALL I have linked the last 35 year averages for Kent Town from the BOM and Weatherzone and these show an average annual rainfall of just over 540mm. This is not a lot and you will not have a 100% yield due to evaporation and first flush losses. The statistics also show that an average 82 rain days of the 116 annual rain days have rain of 1mm or greater. Evaporation during low rainfall days is high and Adelaide has about 30% rain days with 1mm or less rainfall. http://www.bom.gov.au/climate/averages/ ... 3090.shtml http://www.weatherzone.com.au/climate/s ... e&lc=23090 There are also evaporation losses during infrequent hot weather showers and first flush losses can be considerable. You should factor a yield of 85% but many achieve less than this due to most first flush units dripping 4 litres per hour in addition to the capture volume. ROOF HARVEST AREA You need to determine the roof plan area and how you will harvest every downpipe to the tank. What about also harvesting a carport or garage? 22,000 litre UNDERGROUND TANK As you have realised, 22,000 litres of storage capacity is not a lot for self sufficiency. Attention should be paid to pre tank filtering. Having a detention tank supply the underground tank is a good option as it would serve as a settling tank. Determine what the inflow will be during a major storm that is greater than a 1:20 ARI. 22,000 litres sounds a lot but if the tank is half full prior to a storm and you have let's say a 200 sq m roof harvest area, you would not need much more than 50mm of rain to fill the tank. Yield during rainfall is high and the tank overflow 'must' be designed to exceed the inflow capacity. Note that water tank overflow regulations are generally very poor or non existent but I don't know about S.A. Having a detention/settling tank would serve you well here. PUMP You will need a powerful pump when using an underground tank and supplying the house. How far away from the house will the tank be? Have you considered using a decent sized pressure tank to reduce the pump start/stops? WATER UTILISATION First, calculate you anticipated annual rainwater harvest and reduce it to litres per day. You also need to check your area's plumbing regulations as to what you are allowed to do and what you are required to do. For example, when building a new home, are you required to supply the toilets with tank water? TOILET(S) Sanitary flushing accounts for about 8,000 litres and over 2,000 pump start/ stops annually for each household member. Cisterns also fill slowly and the regulations state that a minimum 6 lpm fill rate must be met. Cistern valves seals are also designed for mains pressure and while mains pressure is regulated to not exceed 500 kPa for new dwellings, many older houses have mains pressure well in excess of this. Delivering low flow to a cistern from a powerful pump is not a good combination for reasons of efficacy, energy use and pump wear and tear. You could however negate this by... Using a large pressure tank. Fit a Fluidmaster 400UK063 cistern valve with its pigs tail flow restrictor removed from the shank and the seal replaced by the 242LP071 low pressure gravity fed seal. This seal is ok to use with pumps. http://www.haron.com.au/fluidmaster_products.html Toilets serviced by water tanks must also have either automatic or manual mains water switching devices fitted. I started a thread about this and how most people get ripped off. Most people are not told of their options and end up with a more expensive automatic device. There are however various manual and other devices available like the Apex RainAid plus the cistern can be plumbed with a separate rainwater tank supply line to a second cistern valve (the Fluidmaster is only about $20) that allows the supply source to be switched on and off at the toilet wall. http://www.apexvalves.co.nz/plumbing/apex/rainaid.html SHOWERING You will know what Adelaide water is like and plumbing filtered rainwater to a hot water service will utilise a lot of the harvested water for good benefit. Do some calculations re annual use for showers, washing dishes and laundry. It is still good to have a rainwater garden tap connected. Washing and rinsing a car in rainwater is a lot better than using mains water. I would look at servicing the hot water, the laundry with an additional cold water tap and a garden tap. 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: 22,000 l Rain Tank......Best way to use it 4Apr 24, 2013 12:30 pm Pepsi_Drinker His suggestion was to plumb the WHOLE house to the rainwater tank EXCEPT the toilets and garden taps ! His logic in not connecting the toilets was that they're used quite a few times a day, but only for 3 - 6 litres at a time so not much point running the pump so much for so little benefit ! The plumber is logical on the toilet usage, but you can think about non-pump solutions based on SaveH2O's reply. You haven't said anything about garden taps. If his logic was the same as the toilet usage, it would be wrong. Watering (not drip-feeding or sprinkling) a decent garden can take a good 10-20 minutes of almost continuous usage, so what more benefit do you want from a pump ? If you're worried about the energy usage of a powerful pump, just install bigger pipes & bigger hoses to water the garden faster Re: 22,000 l Rain Tank......Best way to use it 5Apr 25, 2013 11:14 am Wow !! Thanks guys !! I love the Interwebs when they work like this, so much useful information I realised from the start that there was no way we were going to be self-sufficient, but I'm confident that we'll be "reasonably" OK for at least the winter months, and hopefully a fair bit of the Autumn / Spring shoulder months too...... As we're only in suburbia I'm not sure that our limited backyard space will allow for a second settling tank, but the pump-dude suggested a (5 - micron ?? ) Jumbo filter at the tank end to keep the chunky bits out of the toilet and washing machine valves ?? I had previously looked at an accumulator but Davey had told me that they weren't compatible with their Rainbank product. I am now looking at a simpler switcher made by a company in Melbourne called Claytech, it appears to be a hydraulic device with no electronics, and CAN be used with an accumulator. I couldn't find a link with JUST this device, but here it is fitted to two of their pumps (above and submersible) http://www.claytech.com.au/claytech/doc ... manual.pdf Any feedback / comments / ideas on this product ? As we are having in-wall cisterns for the toilets (long story, don't ask ! ) I'm not sure if replacement cistern valve would work in these, but having a decent accumulator would hopefully fix that issue ?? What size is a "large" accumulator ? Mrs P_D has already (before we looked into whole-house rainwater) specified a HiFlow water filter for the kitchen, we'll keep that, it's 0.5 micron capacity and also has a carbon element to reduce / remove chlorine, odours etc. http://everpure.com.au/HiFlowWebsite/Fr ... tions.aspx Any thoughts on this product ? While I'm pretty sure that we generally WON'T use the tank for watering the lawn, I understand both arguments and so where I will have the outside taps (front and back) will probably have TWO taps in each location, rainwater and mains, that'll allow car washing and the like to be rainwater, and both options for garden use. While I thought I had given reasonable consideration to the capture side after reading your replies I realised I didn't really have a clue, a day with Google and now I'm MUCH more informed, thanks guys for pointing me in the right direction !! I also had NOT considered what happens when the tank fills up, Google told me I need a 150mm overflow from the tank to handle that roof area !! Does that sound about right ? Thanks for pointing me in that direction too !!! The tank / (submersible ??) pump will be in the backyard, so no more than just a few meters from the house, but I am not sure of the pressure / flow I should be looking for in a pump, Mrs P_D would NOT be at all happy if there was any pressure / flow difference for her showers between "normal mains" and the rainwater, also when it is used for car / garden use I want "full flow / pressure !! Thanks again guys for your time and advice ! P_D . Block settled 07 June 2011 Our little piece of the Interwebs on HomeOne....... viewtopic.php?f=31&t=48577&start=0 Re: 22,000 l Rain Tank......Best way to use it 6Apr 26, 2013 1:36 pm my 2c... As you realised "there was no way we were going to be self-sufficient", if I were you, I'd put in a mains tap for the EverPure HiFlow filter (use it for drinking/cooking, but not cleaning/washing), and optionally another one for the fridge ice-maker. IMHO I trust mains water quality more and a lot of effort would be needed to maintain the treatment of rainwater to drinking water standard. No opinion about the other aspects of your post, which are too technical for me Re: 22,000 l Rain Tank......Best way to use it 7Apr 26, 2013 2:28 pm downtime ....if I were you, I'd put in a mains tap for the EverPure HiFlow filter (use it for drinking/cooking, but not cleaning/washing), and optionally another one for the fridge ice-maker. IMHO I trust mains water quality more ..... : No opinion about the other aspects of your post, which are too technical for me I'm hearing what you're saying, and I really don't know if I agree with you or not !! My first instinct was to, as you say, go for mains water in the kitchen, but after checking the HiFlow filter specifications, it has (I think) allayed my concerns about the quality of the water that we'd get from the kitchen. I'm pretty sure that I'll go this way, but I'm still not 100% convinced....Maybe 95%, but I would really like to be 100% convinced before I sign off on it !! downtime .........No opinion about the other aspects of your post, which are too technical for me Until a couple of days ago I was (apparently) in the blissful state of "Not knowing what I didn't know" !! Now I'm in the slightly panicked state of "Knowing just how much I don't know" !! Fortunately, forums like this do two things, firstly give you the information you're looking for, and possibly more importantly, open your eyes to things that you didn't know and give you questions that you can go and seek answers for !!! Cheers, P_D . Block settled 07 June 2011 Our little piece of the Interwebs on HomeOne....... viewtopic.php?f=31&t=48577&start=0 As is per usual for many of the past failed RWH regulations, it is probably traceable to a bureaucrat who's ego overrode the need to seek the appropriate expert… 1 1182 That sucks! Hope it all works out. Good to move away from steel anyway for all your reasons, but it's also thermally poor. 16 18168 Can a plumber put a tap on a rain water tank which is full? Tank is similar to one in photo. Cheers. 0 1756 |