Water saving measures are just a drop in the ocean

Over recent years, there has been increased publicity about water saving measures being integrated into buildings. BREEAM pushes for rainwater and grey water harvesting to achieve the highest number of credits, as does the Code for Sustainable Homes. But is this such a great idea?

Consider that water companies benefit from economies of scale - the cost in both energy and carbon for centralised water treatment is far lower than doing it on a building-by-building basis. So any building which has a system for treating water for reuse locally will incur higher costs.

It is a good idea to reduce water use by installing low-flow taps and showers, and smaller baths. But, even if water use can be reduced from around 160 litres per person per day to 130, this is a drop in the ocean. According to the Environment Agency, the main water company in London met its leakage target in 2008-9 when it reduced its leakage from 715 million litres per day to 701 million. This is mostly due to old Victorian pipe work. Admittedly all water companies are addressing this, but this loss far exceeds savings that can be made in buildings.

Leaving aside the water we actively use, what about water used for agriculture and industry? We have all heard that for a cow to become a beef burger requires thousands of litres of water (over 2,000 per burger), and a single T-shirt requires over 2,500 litres, according to the World Wildlife Fund.

While putting water-saving measures in environmental building codes are well-intentioned, they do not take account of the bigger picture. Indeed, after dropping the flow-rate in my shower from 15 to 9 litres per minute, well, 42 days later I have saved the same as if I hadn’t eaten that burger.

Rick Wheal is a consultant at Arup