Flush Toilet with Rain Water
Flush Toilet With Rain Water
Flush your toilet with collected rain water
water | education | generalCollecting Rainwater for use as drinking/washing water is not very difficult, however it may be beyond the DIY skills and budgets of many people. Typically 25% of domestic water is
flushed down the toilet - literally. This is a crazy waste of expensively processed
potable water, and so every home-owner should consider if a
rain water fed toilet flush is practical for their property.
As the image above shows, the concept is very simple. A
water butt (rain barrel) is filled directly or via a (or
rainwater diverter) by the
rainwater which lands on the roof, runs along the guttering, and flows down a
downpipe. This container is then connected to the toilet with a pipe. The whole set up should cost no more than £100 and a couple of hours of your time.
Rain Barrel
Rain Barrels are very easy to find with a search on Google, or in your local garden centre. You may also have something suitable lying around in the garden which can be reused. The bigger the container the better as it means you will have more flush capacity to get you through the dry periods. Typically barrels are 50 - 100 gallons which will give you enough water when full to do well over 50 flushes.
The barrel has to be above the height of the toilet cistern in order for gravity to give the water pressure to push into the toilet. At least 50cm is essential but the more the better. Therefore, you may need to build a structure on which the
rain barrel can sit, or consider installing a solar powered (with battery back up) water pump.
The top of the barrel must have an
overflow drain connected back into the gutter system, so that the barrel will not overflow and cause water damage. The bottom of the barrel must have an outlet
- ideally with a tap/spiggot so you can turn it on and off. A filter should be used at the top (on the down pipe, or across the entry to the barrel) so that debris and flies cannot get into the barrel. A second filter should be added at the outlet as a final defence against getting debris into your plumbing system.
An insulated (against freezing pipe) takes the water from the bottom of the barrel, through a hole in the wall to the area of the toilet where it is connected to a
brass hosepipe splitter which lets you switch between mains water and rain barrel water. That valve is then connected to the toilet cistern. Your toilet may need a little adjustment so it can cope with the low pressure of gravity fed water from the
rain barrel. After that you are finished - one rainwater fed toilet flushing system.
Using a Pump
NEW If your toilet is high above ground level, or if there is nowhere suitable to build a platform for your
water butt, you may well need to go for a slightly more complicated system with a
pump and
header tank. Click here to read our new article
Rainwater Toilet Flush System.
Useful Links
Rain Barrel To Toilet Installation - A practical how-to guide.
Article Last Modified: 15:09, 21st Feb 2008Comment on this Article
If you have any comments on this article, please email them to
neil@reuk.co.uk.
I have been using a rainwater toilet flush system for the last year and a half. My water bill has gone from &pouond;34/month to £9/month. I have found that a standard Whale caravan submersible pump works great, 12volt 2.3 amps (with a non return valve, as they are centrifugal pumps).
I pump water from a distance of 13 meters away and then up 4 meters. The rain water enters the house via the overflow pipe along with a 2 core cable and into the cistern. The cable connects to a tamper switch from an alarm box lid. The lever of the switch touches the float arm in the cistern (so the loo fills automatically when the level drops and stops when full). Power comes from an old car battery charged for 15 minutes every day. I dont need the overflow pipe anymore as i have fitted a flap type flush mechanism with its own 'internal overflow'. I dont have a level switch on my barrel as yet, but have a toggle switch in series with the tamper switch, so after flushing if there is no rainwater splashing down in the cistern I lift the lid off the cistern and turn off the pump/rainwater circuit, then i go back to mains water by turning on the isolation valve under the cistern. Its very simple and there is no way of contaminating mains water as it is protected by a valve and the level in the cistern cannot come into contact with the mains filling pipe due to the overflow drain.
Pictured below are the mains water (left) and rain water (right) pipes feeding the cistern. Note the isolating valve on the mains water feed which is usually left as shown in the closed position, but can quickly be opened manually if the rainwater supplies run down. The hole in the wall through which the rainwater feed passes also permits the low voltage (12VDC) cables through to the cistern:
Peter, 24th January 2010
A query - in your description of the rainwater toilet you describe a valve that will allow a change from Rainwater to Tap water- a brass hosepipe splitter. I dont think this is legal because as you point out in the pumped version there has to be an air gap of 150mm where Tap water and rainwater meet? I am sure that the splitter contravenes the water bylaws.
I note that you list in your section on cistern displacement devices a bottle filled with sand. I have such a system but I have filled my bottle with water which is easier and cheaper. I used to be involved in Water Conservation when I worked for a Water Company and we advocated water bottles. A study I started (but didn't finish as I retired) was looking at double flushing which resulted from putting bottles in cisterns. The bottles are only effective when there is some design redundancy in the bowl. ie some bowls need 13 litres to flush everything away. If double flushing occurs then reduce the volume of the displacement device otherwise you may use more water. Better still get a replacement dual flush siphon. Keep saving
Paul
December 3rd 2008 |
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