Image copyright Thinkstock Image caption Licensed premises are being encouraged to always give children free tap water to drink

Restaurants should offer free tap water to families eating out rather than waiting for customers to ask for it, says a body representing councils in England and Wales.

They say this would offer a healthy alternative to sugary drinks.

Councils, which have responsibility for public health, want restaurants to do their bit to tackle childhood obesity.

All licensed premises have to provide free tap water in England, Wales and Scotland - but not Northern Ireland.

Yet one in five people are not aware of the rules, says the Local Government Association.

And a survey found that 15% of people who usually drink tap water at home never think of asking for water in cafes and restaurants.

Izzi Seccombe, community wellbeing spokeswoman at the Local Government Association, said: "While most restaurants will happily provide a glass of tap water on request, we're saying it shouldn't be something you have to ask for.

"Some people may be too embarrassed or find it awkward to ask for tap water. Others may simply forget it's an option," she said.

"Water brings important health benefits and keeps people hydrated.

"For children it's an alternative to a sugary drink, while for adults it might dissuade them from ordering another alcoholic drink."

The LGA has previously called for tap water to be made more available in schools, nurseries and children's centres.

It wants the government to introduce initiatives to encourage children to drink more water as part of its childhood obesity strategy, which has been delayed and will probably not be published until the summer.

The Chancellor, George Osborne, recently announced a new sugar tax on the soft drinks industry to help tackle childhood obesity. It will be introduced in 2018.

One in 10 children in England is obese at the start of primary school and that rises to one in five by the age of 11.