COUNCIL Tax bills for Plymouth householders would increase under a switchover of levying road drainage costs, writes Nick Lester.

But backers of a change in the system to pay for rain run-off from roads owned by the local authority argue it is 'fairer' than slapping the cost on water customers.

A review on water charging, headed by Anna Walker, is now seeking views on the possibility of transferring highway drainage costs from utility companies to local authorities.

In theory, as the tax burden increases with the switch in charges there would be a corresponding fall in water bills, although this is not explicitly stated in the review team's interim report.

South West Water, the industry regulator Ofwat, and the Consumer Council for Water are among those who agree in principle with the transfer.

The interim report states that highway drainage charges to pay for the collection, removal and treatment of rainwater run-off from roads and pavements, represents on average seven per cent of the combined water and sewerage bill – around £25 per household.

The total annual highway drainage charges recovered from all water customers amounts to approximately £700 million.

And highway drainage is expected to take on greater significance in the future as climate change leads to more flooding. Many water customers are also unaware that they are paying for road drainage.

Outlining the argument in favour, the report says that shifting costs to local authorities would be in line with the "polluter pays" principle and would be an incentive to deal with the amount of run-off through sustainable drainage systems.

Councils would also have to explain what the costs were for. Local highway authorities own 97.5 per cent of the road network.

The report also says that in the future, existing homes will need to be 'incentivised' to cut the amount of water run-off from a property, including installing small-scale sustainable drainage systems.

It considers whether household charging should reflect more the surface area of each property.

This would be inline with Ofwat's controversial approach for charging non-households for surface water drainage, which has seen water bills rocket for sports clubs, churches, and community groups.

But in recognition of this, the report states: "We note, however, how controversial the introduction of charging for surface water drainage has been for non-households in areas where charges have risen very sharply for some customers."

A South West Water spokesman said: "We believe the current system of charging for surface and highway drainage could be made fairer and more efficient. One possible solution would be to allow water companies to charge highways authorities for highways drainage.

"Although this would move the charge to the Council Tax bill, the costs would be spread equally to include those customers not connected to our sewers and who currently do not pay sewerage charges. It would also allow those least able to pay to seek support through the existing benefits system."

A Local Government Association spokesman, which represents councils, said: "Councils would want to be sure that any new burden to manage drains is going to be properly funded and not place an extra cost on council taxpayers. Councils would need to know where funding to create more sustainable drainage is going to come from."