Youngsters in Preston have some of the most rotten teeth in the country and more than half of five-year-olds in the city have had experience of tooth decay.

Now dental health specialists want to reduce overall levels of cavities by supporting the introduction of water fluoridation in Central Lancashire.

Investigations are currently underway to find out the cost of such a scheme and what benefits it would bring about for children and adults.

The legislation surrounding fluoridation of tap water was changed about two years ago and Primary Care Trusts now have the power to ask the Strategic Health Authority to launch a consultation on fluoridating water supplies.

Bosses at Central Lancashire Primary Care Trusts are working with water companies to find out the costs and practicality and will then make a decision.

They can then request the Strategic Health Authority to undertake a public consultation into water fluoridation.

A spokesman for Central Lancashire Primary Care Trust said: "The PCT is a member of the North West PCTs Fluoridation Evaluation Group and is supporting work to establish the feasibility of water fluoridation schemes in the North West.

"This involves understanding the water distribution systems, the practicality of making adjustments at water treatment works and the costs associated with this.

"It is expected that the group will report its findings in the New Year.

"The PCT will consider the outcomes of this work before making any further decisions. Any proposed water fluoridation scheme will be subject to a public consultation exercise governed by regulations."

Many areas of the country have added fluoride to water since 1964 and it has improved dental hygiene.

In areas such as Birmingham and the North East where water has been fluoridated for decades, levels of tooth decay are much lower and fluoride is also widely used in the US.

However, some people are against the idea as they believe it may be linked to a variety of diseases such as osteoporosis, bone cancer and allergies.

A spokesman for NHS North West today said: "At the moment, work is being done to see how much it will cost to fluoridate drinking water in the area.

"Water supplies in different parts of the country have been fluoridated for about 40 years and children there have fewer caries in their teeth.

"There are benefits for adults too, especially in the elderly who often suffer from receding gums.

"There have been claims of fluoride causing health problems, but there is absolutely no evidence to support this."