Water Reduction

To achieve reductions in the water consumption of dwellings, there are a number of devices with potential to help limit unnecessary water use. For example: Sensor taps.

These are activated by placing your hand in front of the sensor. Once removed the water supply is cut off. This can reduce the need for large storage tanks in some areas, especially if mains water is in short supply.

Double flush toilets
Double flush toilets are effective at reducing the need for extensive mains water, sewage and drainage provision. The flushing mechanism regulates the amount of water supplied to the cistern and pan. The mechanism involves choosing a button to determine the water supplied depending on the effluence.

Monitoring devices - metering water
Water meters are designed to measure water consumption; they can be installed into a property (commercial / residential) despite its age. The meter is attached to a mains water pipe and will be able to monitor the flow of water and help to indicate areas of potential water conservation. The meter will monitor the water flow during the day (24hr cycle). Users will be able to ascertain when water usage is high and, as a consequence, establish areas where savings can be made. Although not construction related it doesn't matter as it is still useful.
http://www.envirowise.gov.uk/gg522