Understanding Your Water Footprint: Complete Conservation Guide

A water footprint is the volume of fresh water used to produce the goods and services someone consumes. It has two parts:

• Direct water: water used at home, such as showers, toilets, cooking and gardens. Your water bill or meter measures this.
• Indirect or "virtual" water: water used to grow, make and transport food, clothing and other products. No meter shows this; it is estimated with published footprint factors.

Water-footprint accounting (Water Footprint Network method) splits water into three colours: • Green: rainwater stored in soil and used by plants • Blue: surface water and groundwater that is withdrawn and not returned • Grey: the volume needed to dilute pollution to agreed water-quality standards

These are not interchangeable. A litre of rain-fed green water in a wet region does not have the same impact as a litre of irrigation water pumped from a stressed aquifer.

Published food water footprints are global averages that combine green, blue and grey water. Individual farms and countries can differ greatly from them, and most of the total for animal products is green water used to grow feed.

Direct use is the part you can measure. Read your water meter at the start and end of a day or week, or check the volume on your water bill. To estimate a shower, time how long a bucket of known volume takes to fill, giving a flow rate in litres per minute, then multiply by your shower length.

Appliance labels state water use per cycle for dishwashers and washing machines; use those figures rather than general averages.

Water impact depends on where water is used. Blue water withdrawn in a water-stressed region matters more than the same volume used where water is plentiful. A total footprint in litres says nothing about this on its own, which is why water-footprint studies often add a scarcity assessment.