Southern Water has clarified its position on the addition of fluoride to the public drinking water supply after MPs voted they could be forced to add it.

The company does not presently add fluoride to the water of any area it supplies but could now be required to do so by the local health authority as a result of new Government legislation.

Water companies have had the power to fluoridate supplies since 1985 but most have not done so for fear of legal action from consumers opposed to it.

Health authorities will now be given the power to force water companies to fluoridate supplies after local consultation.

Dr Nigel Smetham, water quality manager for Southern Water, said: "Southern Water does not have the medical expertise to judge the effects on dental health if we have to add fluoride.

"However, with our expertise in engineering and water treatment, should this situation change we are quite happy to provide health authorities with technical advice in relation to the operation of the water supply system."

The company said fluoridisation was a public health issue not a water quality issue and the company would therefore seek indemnity for it as the process would extend beyond its responsibilities under current legislation.

Dr Smetham added: "Southern Water is taking a keen interest in the views being expressed by its customers, and will expect the health authorities to carry out extensive public consultation."