The company says it is currently testing two-devices in 60 homes as part of a research programme into domestic water use. The devices are the EcoFlush and the Variflush, both of which cost around £20 each but can save up to 40 litres of water per household per day.
The move could herald the opening of a substantial market for the kits among water companies seeking to increase water resources in areas of scarcity.
Thames Water's scheme was included in its business plan for 2005-2010 and submitted to the industry's economic regulator Ofwat in April. It is subject to the trial showing worthwhile savings.
The devices were prohibited under the water regulations until recently, although research by the Environment Agency highlighted the potential for significant water savings (ENDS Report 332, p 36 ). Relaxations to the regulations in England, Wales and Scotland now permit the use of the devices to non-low flush WCs fitted before 1999.