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Retrofitting variable flush mechanisms to existing toilets (2005)

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Environment Agency

This reports analyses a water effiiciency project trialled by the Environmental Agency and several water companies to further knowledge on the suitability of retrofit devices for demand management programmes. Two devices – Ecoflush and Variflush – were installed in domestic properties. The project used water consumption data gathered from 136 properties and feedback collected from 271 customers. In the weeks after the devices were installed, water demand fell by an average of 8.5% per property. Reductions were insignificant between the two devices, yet varied strongly between the different properties.

Executive summary

Toilet flushing has traditionally represented the largest single use of water in households, accounting for around 30% of total domestic water use. While the Water Supply (Water Fittings) Regulations 1999 reduced the maximum volumes of new toilets to 6 litres, a large proportion of existing housing stock has toilets which flush 7.5 litres or more.

Retrofit variable flush devices convert an existing single flush siphon cistern to a variable flush mode, offering a potential for reducing existing flush volumes without the expense of a complete toilet replacement.

This project is a collaboration between the Environment Agency and the following water companies:

Anglian Water
Bournemouth and West Hampshire Water Environment Agency
Essex & Suffolk Water
Southern Water
South West Water
Sutton and East Surrey Water
Tendring Hundred Water
Thames Water
Three Valleys Water

The project built on the results of a previous trial of retrofit variable flush devices. Its aim was to explore further whether retrofit devices are suitable for demand management programmes.

Two devices – Ecoflush and Variflush – were trialled in domestic properties. The project used water consumption data gathered from 136 properties and feedback collected from 271 customers.

In the weeks after the devices were installed, water demand fell by an average of 8.5% per property. There was a wide variation between properties. This depended largely on the way the devices were used, the size of the household and type of the property. There was not any significant difference between the two devices.

Feedback from customer and installers was generally positive, although it included comments about improvements needed.

Savings could potentially be increased in two ways. First, by targeting specific groups of customers; second, making sure they know how to use the devices correctly.

The devices could help reduce domestic demand for water. However, the overall benefits would depend on how the devices are promoted and distributed. It might be necessary to conduct pilot studies on a wider scale to establish the take-up rates by customers.