Hard-pressed water customers in Sussex face a further rise in their bills after the Government ordered water companies to take charge of thousands of miles of private sewers and drains.

Water Minister Ian Pearson said ownership of more than 8,000 miles of "unadopted sewers" would be transferred to Southern Water, together with responsibility for maintenance and repairs.

A spokeswoman for the Department for the Environment, Food and Rural Affairs (Defra) said the move would release householders from a liability most did not even realise they had "until something goes wrong and they face a bill for fixing the problem".

It would also make it easier to identify who was responsible when a sewer problem occurred.

Up to 50 per cent of properties currently connect to sewers or drains which lie outside the public network.

It is hoped water companies will be able to manage them more efficiently and prioritise problems.

But consumers as a whole will have to pay for the adoption of private sewers and drains whether they benefit or not.

The costs will be met by increasing the sewerage element of each customer's annual bill by between £3 and £11.

The move comes as average bills for Southern Water customers in Sussex increase from £309 to £328 on April 1.

The Consumer Council for Water welcomed the transfer but reminded financial regulator Ofwat to keep a close eye on the cost to consumers.

Chairwoman Dame Yve Buckland said: "All water consumers will foot the bill, and will want to know the exact cost of transferring private sewers into water companies' hands."

Across the country nearly 100,000 miles of unadopted sewers and drains will be transferred to nine water and sewerage companies.

The Government will launch a public consultation to seek views on how the transfer should be implemented and how it can prevent the proliferation of new private sewers.