Browse Forums General Discussion Re: basix water tanks 2Aug 06, 2012 7:18 pm Its more working out how much water you use. There is some advice here: http://www.anewhouse.com.au/?p=653 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: basix water tanks 4Aug 06, 2012 9:36 pm If you are not going to be using much water there is not a lot of point in putting in a huge tank even if you have a big roof. For instance if you are going to be be only flushing toilets you may only use 50-60L/day. A 2000L tank will last for more than a month without rain. Only 10mm of rain on a 200m2 roof will refill it. If you got a bigger tank and didn't use more water it would simply overflow most of the time. 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: basix water tanks 5Aug 07, 2012 12:15 am Amazing! I have looked at the BASIX web pages as well as NSW council websites and water tank retailer sites and none mention minimum roof areas or tank sizes. A few BASIX sites do show poorly installed tanks and a photo of a non compliant product though! There was and may still be a BCC (QLD) requirement for a tank to harvest a minimum 50% of the roof area or 100 sq m., whichever is the greater. This has led to huge numbers of tanks overflowing when the tank has filled and the overflow has not been able to cope with the inflow. The situation above is one that you need to avoid. In Victoria, a 6 star home has to be connected to either a solar hot water service or a 2,000 litre rain water tank that harvests a minimum roof area of 50 sq m. The problem is that the popular downpipes fitted harvest less than this area! Unless the tank harvests two downpipes, the roof area harvested will not be compliant with the 6 star requirement. If it harvests two downpipes, the overflow pipe's capacity is often less than the inflow capacity and the plumbing is consequently not compliant. This obviously means that there are probably tens of thousands of 5 & 6 star homes that were sold as meeting the standards when in fact they did not. If you phone BASIX and get some regulatory guidelines, I would be interested in reading them. 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: basix water tanks 6Aug 07, 2012 9:30 am It may also be a Council thing, and I don't know how they arrive at their requirements. We originally started with a 3000 ltr tank but Council required a min 5000 so now we have 2x3000 Re: basix water tanks 7Aug 07, 2012 12:37 pm Leaving aside the environmental factor, as far as running costs go what is cheaper electricity to run a pressure pump everytime you turn on a tap or paying water rates. I know a number of people who have turned off their pumps and just use mains water because they believe the electricity cost of running the pump outweighs savings in water cost, is this true? Re: basix water tanks 8Aug 07, 2012 12:46 pm Pump doesn’t cost that much to run. With water in Melbourne you get charged to buy water then also to put water through sewerage. So you can save twice here. Let do the maths. I have a 500watt pump so that means it cost 10cents approx per hour to run. In that time is can pump 3000 litres approx. From my bill that will cost about $2-3 to buy. Then it would cost almost similar price to put through sewerage. I also have a tap running off my water tanks and I can use gravity feed to water garden. Its really important to reduce your usage of water that way you don’t get yourself into the higher pricing category. Re: basix water tanks 9Aug 07, 2012 3:13 pm roadrunner14 Leaving aside the environmental factor, as far as running costs go what is cheaper electricity to run a pressure pump everytime you turn on a tap or paying water rates. I know a number of people who have turned off their pumps and just use mains water because they believe the electricity cost of running the pump outweighs savings in water cost, is this true? Most tank owners have been ill informed (after getting ripped off). It is easy to plumb a tank to a toilet so it runs on gravity feed for most of the year. This will save about 2,000 start up per resident per year. As B STAR has posted, gardens can be gravity fed from the tank. People can still make mistakes here as most will use unsuitable drip hoses rather than the made for purpose gravity fed drip hoses that have larger emitters. Many people also don't know that water will flow through a pump when the pump is not on. People get conned into buying large expensive pumps when they want a tap connected for garden watering. An 18 mm hose at 20 lpm has 8 times less friction loss than a 12 mm hose. An 18 mm hose fitted with a short length of 12 mm garden hose (so that 12 mm hose fittings can be used) is a lot more efficient and cheaper than buying a bigger pump. One of my customers was recently conned by a plumber who sold him a $1,200 pump when all he needed was an 18 mm hose and a small pump. The pipe between the pump and outside tap is commonly too small. It should be big to reduce friction/pressure losses. I often see 1/2" copper pipe fitted. You should also not use copper pipe with rainwater. Buying a large pressure tank reduces pump start ups plus it also eliminates washing machine water hammer. Most tanks are under utilised, particularly during winter. This is money and water wasted. La Nina has officially ended and there is a good chance that we will soon be back to an El Nino climate. 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: basix water tanks 11Aug 09, 2012 9:23 am Here is a rough guide of how I worked out our water needs etc for our intended reno based on our current usage and proposed roof area. Calculating rainfall and tank size Using data from here... http://www.bom.gov.au/climate/data/ and selecting weather stations from here... ftp://ftp.bom.gov.au/anon2/home/ncc/met ... SW_139.txt Now you need to measure the roof horizontal area that will be drained to the tank/s in m2. Depending on the roof shape it may not be practical to drain the whole roof to a single tank. Multiply the area m2 by the rainfall in mm for each month and divide by 1,000 will give you the volume of rain in kilolitres Area of proposed roof ( Revision 15 floorplan ) = 210 sq m so... Site Name Lat Long 066153 MANLY VALE (MANLY DAM) -33.7822 151.2556 Jun 1906 Oct 2006 50.8 50 N Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Mean 115.9 113.8 126.3 138.6 119.7 102.6 98.4 72.7 70.9 73.1 86.0 85.9 1225.6 kL ave 21.1 --> 21.1 Average rainfall = 1225kl per year so each month averages out to approx 100kl So Rev 15 roof of 210 sq m can hope to collect each month 21.1 kilolitres of rainwater Going by the last three water bills we consume approx 20,00L per month ( we should look at reducing that markedly but try telling that to my daughter when she is in the shower !!! ) As a comparison; if you can keep to the water boards Target 155L per person per day that is the equivalent of 57kLper person per year. 155L x 30 days = 4650L per person per month 3 people should consume 13950L per month Looking at all this, if we decided to use our rainwater for all our water needs we should in theory not have to buy any water at all but we may decide to use mains water for just the kitchen and recycle the kitchen waste water for our garden. We are looking at something like a Davey ST25-03cp pump which consumes 0.5kW per hour It will pump about 25 litres per minute so to pump 1000 litres for our house should take 40 minutes. Our electricity is costing us about 22c per kW We are being charged about $2.00 per 1000 litres from the council So it should cost us about 15 cents to pump 1000 litres of water. These are rough figures only and I haven't taken into account the extra electricity the pump will consume to pump the water up to the second floor nor allowing for any gravity fed outlets as other posters have stated above. What it does give us though is the approx savings that a rainwater tank can provide which in our case is $2.00 ( per 1000L ) minus 15c ( cost of power to run the pump ) = $1.85 per 1000L of water x 20 ( 20,000L per month consumption ) = $37 per month. x 12 = $444 per year we will save. Stewie Re: basix water tanks 12Aug 09, 2012 12:50 pm Just be aware that rainwater harvesting does not give a 100% yield. It is an optomist who expects more than 85%. Also, most regulations and common sense require the tank overflow to be able to handle the inflow when the tank fills. There have been many tens of thousands of people caught out by non compliant plumbed tanks overflowing in recent years. I mention common sense because some councils have actually overruled this basic requirement. 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: basix water tanks 13Aug 09, 2012 4:00 pm We were aiming for about 75% max ( according to a water tank article I read a while back ) so we should be covered. We also have another 60 sq m of roof that we may run to a secondary tank that is not included in our original calculations. Stewie Re: basix water tanks 14Aug 10, 2012 8:45 am SaveH2O Just be aware that rainwater harvesting does not give a 100% yield. It is an optomist who expects more than 85%. Also, most regulations and common sense require the tank overflow to be able to handle the inflow when the tank fills. There have been many tens of thousands of people caught out by non compliant plumbed tanks overflowing in recent years. I mention common sense because some councils have actually overruled this basic requirement. what does this mean. Where does the 15% go? Re: basix water tanks 15Aug 10, 2012 11:28 am B STAR what does this mean. Where does the 15% go? Not all the rain gets as far as the gutter. If you only get 1-2mm of rain it will evaporate. Quite a bit of the measured monthly rainfall will be in these 1-2mm showers. Also you are going to be losing a bit if you have got first flush systems to take off the water that washes the dirt off the roof. 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: basix water tanks 17Aug 10, 2012 12:55 pm B STAR Where does the 15% go? A good question and well answered by bashworth. The BOM will have the annual statistics for rainfall in your area and this will include the number of days where rainfall is less than 1 mm. Taking Melbourne as an example, nearly 1/3rd of all rain days have falls of less than 1 mm. Add to this the frequent short showers on hot days when the daily rainfall is over 1 mm plus the yield lost to first flush diverters as already mentioned by bashworth, you can readily see why there is significant yield loss. It irks me to see false advertising claims about 100% yield. Harvesting rainwater is still worthwhile but unfortunately those that have made a commitment to conserving water still have to pay the price for expensive engineering solutions. I for one absolutely resent having to pay for infrastructure costs of expensive white elephants when my mains water use is well below the daily use targets. Despite yield loss, most tanks are under utilised and this is a huge waste of a harvested resource. 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: basix water tanks 18Aug 10, 2012 1:06 pm B STAR I bet it would be more effecient for colorbond. Colorbond gets hotter but a yield comparison is variable and dependent on the age and condition of a cement tiled roof if comparing the two. The upside is that metal rooves clean more efficiently and the heat has a sterilising effect on bird droppings. 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: basix water tanks 20Aug 10, 2012 2:59 pm You would be surprised at the number of houses l see that harvest a downpipe that is close to a TV antenna (bird perch) or in the rain shadow of a large tree. 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 17367 18 90494 |