Donnachadh McCarthy: The Home Ecologist

"We are suspending all payments from 1 November." When I read the opening sentence of the letter from Thames Water, my heart sank. My ex-Catholic conscience immediately wondered what I had done wrong now! It was only when I read further that I started laughing, when I realised they were suspending payments OUT of my account.

A year previously I had had a water-meter installed in my house, instead of paying my bill based on the rateable valuation. As a home eco-auditor I advise people to switch to water meters, so they become financially and environmentally accountable for their water use. I had decided to practice what I preached, even though I already had a low-water lifestyle. Most water companies will install meters for free, and you can switch back after a year if you do not like the new charges.

After a year they also review your direct debit and they had so overestimated my consumption that I had to pay nothing for the whole of the next year – after which time I would still have about £5 in the kitty. I had used just over 9,000 litres of mains water, which is about 26 litres per day, or a sixth of the average Londoner's consumption.

Most savings come from the fact that I am careful with what I use. I do not run the tap when shaving, washing vegetables, rinsing dishes or washing my teeth. I divert my washing machine water to the garden in summer and have short gentle showers, rather than an eco-criminal daily bath.

However, some of it is because I had a rain-harvester installed by a plumber mate of mine, back in 1996. This is just a fancy name for a rain-barrel on the flat roof of my bathroom, which collects water via guttering from the upper roof and has a simple filter. It is plumbed to supply the loo, and a tap in the bathroom, with rain-water via gravity through a couple metres of piping. The legal caveat is the plumber must ensure the valve prevents mains and rainwater ever mixing. A variation is one which switches to the mains automatically when the rainwater runs out, by simply using two stop-cocks instead of one.

Some rain-harvesters can be put together by any knowledgeable plumber. Others are large, professional systems with tanks buried in the garden and motorised pumps, such as those made by Envireau. Progressive developers are beginning to install these in new homes. If you are having a new home built, it really is worthwhile getting one put in.

About 40,000 litres of water falls every year on the average UK roof, and we spend huge amounts of money pumping it away, cleaning it with chemicals and pumping it back to our homes through leaking pipes – and all just to just flush it down the loo. More than a third of our household drinking-quality water is flushed down the pan. Is this not just the most stupid system that could have been invented?

It is a massive climate crisis problem also. Over four million tonnes of CO2 are emitted by UK water companies every year, pointlessly pumping huge weights of water around the country. So get water wise – not only is it part of your carbon diet but you might also have a more positive financial relationship with your water company.

Donnachadh McCarthy works as an eco-auditor and is author of Saving The Planet Without Costing The Earth (www.3acorns.co.uk)

d.mccarthy@independent.co.uk