Device could help save water while hot tap is warming up

A new device could help cut the amount of water wasted while waiting for a hot tap to warm up.

The prototype technology developed by a student at Brunel University in London detects the temperature of water when a hot tap is turned on and diverts the stream into a pressure tank until the flow reaches a specified temperature.

Inventor Mitch Gebbie said the tank could store five litres of water at a time, the equivalent of two 30-second bursts of a tap, and cut the average household water usage by up to nine litres per day.

‘It’s five per cent of your annual water bill that you’re pouring down the drain, that’s the average estimate, although obviously it’s going to vary between different households and different people’s uses,’ he told The Engineer.

The device makes use of a simple microphone to detect when the tap has been turned on, instead of a more costly flowmeter, and temperature is measured through the thermally conductive copper pipes.

An electronically controlled valve diverts the water into a tank connected to but at a higher pressure than the cold supply so that, when the cold tap is turned on, the tank automatically empties back into the pipes.

Gebbie said the system was designed to be easily retrofitted in existing houses. ‘There are things that you put on the bottom of the boiler that restrict the flow rate until it’s hot and you use a third of the amount that you would usually waste, but this is 100 per cent.

‘Water-return systems that have a small pipe that goes back to the boiler have to be implemented when the house is built, whereas this is retrofittable.’

He is now looking to develop the system into a commercial product.