Drought Orders could have a devastating impact on forecourt businesses unless there is some dispensation made for car washes, says the Association of Convenience Stores, which is arguing the case against Thames Water on behalf of retailers. The water company has applied for a Drought Order covering London and the Thames Valley, but ACS public affairs director James Lowman said the proposed terms were extremely strict.

"Even garden water features are included, so Thames Water is casting its net far and wide to restrict what it deems to be unnecessary water usage," he said. "Our case is that car washes are not only necessary for the survival and prosperity of forecourt traders, but they also offer the most efficient way of cleaning cars in the area."

The ACS is writing to Thames Water and to the Department for the Environment, Food & Rural Affairs to make its case for a car wash exemption from the Drought Order: "The proposed Order allows only for people to clean their cars for the purpose of safety and hygiene," said Lowman. "Clearly that means that windscreens and other windows must be kept clean, and in order for the police and congestion charge cameras to be able to do their job, number plates will have to be legible too. All the water used by households to keep cars clean to this standard is lost down storm drains, whereas most of the water used in car washes is retained in the system.

"The amount of water lost in car wash centres compared to even limited domestic car washing shows there is no compelling environmental case for banning car washes under this Drought Order."

The case is even more clear-cut when it comes to car wash centres with recycling facilities. On this issue, ACS is calling on Thames Water to follow the lead of Sutton and East Surrey Water in exempting car washes with water recycling: "Even if car washes are to be banned - and we don’t believe they should be - there has to be different treatment for those which recycle their water," said Lowman.