The River Cherwell has become almost entirely dependent on sewage plants for water because of the drought sweeping the south of England.

And the upper parts of the River Ray, which rises from springs in the East Cotswolds, have already dried up.

Last night the Environment Agency (EA) confirmed reports that the Cherwell, which runs through North Oxfordshire to flow into the Thames in Oxford, was relying on “man-made” water to stop it from drying up. The news comes as the agency prepares to publish a ‘water prospects’ report which is expected to warn of a water supply crisis following two years of exceptionally low rainfall.

It is also expected to warn of the dire environmental consequences of the drought on wildlife.

Both little grebe and brown trout, which are particularly sensitive to water quality, are said to be under threat.

The agency also confirmed the Kennett in Wiltshire, the Wandle in south London, and the Ouse and Nene in East Anglia were dependent on man-made water but refused to release a further statement.

So called man-made water, which is heavily treated sewage works water, has to meet agency standards before it is released into rivers.

But its chemical make-up is significantly different to natural river water.