Flush Toilet with Rain Water

Flush your toilet with collected rain water

Collecting Rainwater (1) 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.

Collect rainwater and use it in toilet flush

As the image above shows, the concept is very simple. A water butt (rain barrel) is filled directly or via a (or rainwater diverter (2)) 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 Ł100 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 (3).

Useful Links

Rain Barrel To Toilet Installation (4) - A practical how-to guide.

Web Link References

(1) http://www.reuk.co.uk/Collect-Rainwater.htm
(2) http://www.reuk.co.uk/Rainwater-Diverter.htm
(3) http://www.reuk.co.uk/Rainwater-Toilet-Flush-System.htm
(4) http://www.geocities.com/pmm1018/rain_barrel1.html

Article from REUK.co.uk:
http://www.reuk.co.uk/Flush-Toilet-with-Rain-Water.htm
Published: 21st February 2008
Š REUK 2009