What is it? Hippo the Water Saver is a small water-saving device, made of toughened plastic, that can be fitted into a household cistern.

How does it work? Each Hippo has a small hole punched through two sides, which lets in water from the cistern. When the loo is flushed, the water confined in the Hippo is saved.

How green is it? It conserves up to 3l of water with every flush.

How much could it save me? It could knock £20 per year off your water bills. You get a return on your initial investment in about 10 weeks.

How easy is it to install? Very — you just unfold the Hippo and pop it into your cistern according to the illustrated instructions. If your loo was installed after 2001, however, or is operated via a push button, the cistern will be only 6l, so will not be suitable for a Hippo.

How much does it cost? £1.99, plus delivery.

Is it worth it? Yes, if you’re concerned about wasting water through multiple flushes; but your loo may require more regular cleaning

Where can I get one? The Ethical Superstore is running a buy one, get one free offer; call 0800 999 2134 or visit ethicalsuperstore.com. Or get a household pack of three Hippos for £7.82 with free delivery direct from the manufacturer; hippo-the-watersaver.co.uk

- A wormery is a great way to help the environment for those with no garden, as rotting food waste that is sent to the landfill is a big source of pollution. A tub of the wriggling creatures is a good alternative. Ask your local council if you can buy a subsidised wormery kit (they cost about £15). It is a cleaner and less squeamish business than I thought, takes up little space on my balcony and disposes of food waste.

Laura Perry, by e-mail

Do you have any green tips? Or have you used a product featured in this column? Tell us at greenhouse@sunday-times.co.uk

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