Having visited the Centre for Alternative Technology on our holiday (more of that to come later) we bought a couple of attachments for our taps that are supposed to save water.
They work on the same idea that a shower uses less water than a bath. By forcing the water through small, spread-out holes, less water is used but appears to be just as useful.
We bought two attachments for taps that have no screw fitting. They are from TapMagic and have two flow rates. The low flow rate is just the shower, sprinkler-like water and, if you turn the tap on more, a centre stream of water is also provided.

Tap Magic
It was easy to fit it onto the taps. I quickly fitted it to the cold tap. Then I noticed the claim that it would save 70% of the water on a normal tap. Really? Could it be that much?
Here’s the science bit
I got a jug from the cupboard and with the help of Daisy, we timed 5 seconds and measured the throughput of water on the standard hot tap (on full pelt). It used about 900ml, which is just under 11 litres a minute. I then fitted the TapMagic and we re-did the test. With the TapMagic fitted (on full pelt) it used approximately 600ml, which is just over 7 litres a minute. That’s a saving of a third. Great!
However, we never use the taps on full pelt. As the TapMagic has a dual-flow mode, we measured how much water was used in low-flow mode. This is what you’d use to wash your hands or brush your teeth. In this mode it used about 250ml, which is onl 3 litres a minute. That nearly is a saving of 75% on the full-pelt original tap (perhaps an unfair comparison though).

900ml

600ml

250ml

Tap flow - before

Tap flow - After
At £5.50 each, they’re not all that cheap, but I guess that kind of money is easily made back over a short amount of time with those kind of savings. Unfortunately, they’re only available for round-holed taps, so our kitchen tap cannot be retrofitted, nor can the bath.