The Beijing Water Authority issued 36,000 carwash coupons on Saturday to promote water conservation across the service industry.

The coupon, which can be exchanged for a free service, will be distributed at car clubs across the city. They can also be collected at the Beijing water conservation exhibition hall at Ji'enli, Haidian District, the authority said.

It added that the coupon is valid at the 15 branches of three major carwash shops across the city - Yuefu Automobile Car Beauty, Aiyihang Auto Service Co and the China Petroleum and Chemical Lubricating Oil Branch.

"We want to encourage people to wash their cars at qualified stores where recycled water is used," said Cheng Jing, chief of the Beijing Water Authority.

Cheng claimed many carwash companies use tap water in their services and waste a great deal of the limited resource.

The authority hopes to address the issue through a promotional activity to highlight law-abiders.

"If the public doesn't use these vendors, they might even disappear," Cheng said.

A regulation on water conservation, which came into effect in May 2005, stipulated that companies engaged in the carwash industry only use recycled water. Fines of up to 20,000 yuan can be handed out to violators.

However, many companies still use the cheaper alternatives of tap water and industrial water, said Xing Aiyi, president of Aiyihang Auto Service Co.

Beijing raised the industrial water price from 41.5 yuan to 61.68 yuan per cu m in November. Tap water costs significantly less, 3.7 yuan per cu m.

Xing said many carwash businesses charge as little as 10 yuan per service because they use tap water, Beijing Daily reported.

The standard charge for a carwash should be 25 yuan, according to price lists from local carwash businesses.

Although recycled water costs only 1 yuan per cu m, Xing said it is not widely used because relevant underground piping does not cover the city sufficiently. As a result, transportation expenses can jack up costs to as much as 20 yuan per cu m.

Carwashes purchased only three million cu m of recycled water in 2008, in addition to 23,000 cu m of industrial water, according to the Beijing Water Authority.

However, the authority estimated the total annual water consumption for the industry was actually 12 million cu m, meaning that about nine million cu m was tap water.

"Authorities need to inspect carwashing companies more regularly and strictly," Xing said.