Water: Should Wales sell to England amid heatwave droughts?

Rain could become Wales' oil of the future if moves to send water to drought-stricken parts of England are realised, an expert has said.

Prof Roger Falconer of Cardiff University said cash from sales should be reinvested into Welsh communities.

It comes as Thames Water considers plans to tap into a Powys reservoir to supply London during future droughts.

But Wales Office minister David TC Davies warned charging England for water would "stoke divisions".

He said "a problem in one part of the United Kingdom is a problem for us all".

Prof Falconer, an expert in water management and engineering, said people had been looking at this idea since the early 1980s.

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In 2011, Prof Falconer said he was called by Boris Johnson about the issue, when he was mayor of London.

They discussed the possibility of raising the Craig Goch Dam in the Elan Valley, transferring the extra water captured there via the rivers Wye or Severn and through canals to the upper Thames.

Two water companies border Wales, Severn Trent Water and United Utilities, and need what is called an abstraction licence to pump water out of the country, with the companies licensed to take millions of litres a day.

However, with water companies across south-east England warning of "severe pressure" on resources as a result of population growth and climate change Prof Falconer believes there will be "growing interest" in new schemes.

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Speaking to Newyddion S4C he said: "We would directly be supplying under drought conditions to the south-east of England and I would see this as Wales' oil for the future in terms of revenue."

Meanwhile, Thames Water has been urged by the union GMB London to plough ahead with plans it has floated to access water from Lake Vyrnwy reservoir in Powys during periods of drought.

It is one of a number of options being considered by the firm, which has more than 15 million customers in and around London and this week implemented a hosepipe ban.

The firm said it had been "consulting on and developing a regional water resilience plan which takes into account the viability of different schemes and how they will help provide an affordable, resilient, and sustainable water supply for future generations".

A spokeswoman added: "One of these is the Severn Thames Transfer, which we're exploring with United Utilities and Severn Trent."

The plan would involve transferring water from the Severn to the Thames via a new pipeline, or using restored canals in the Cotswolds.

Additional water could also come from Lake Vyrnwy, managed by Severn Trent on behalf of United Utilities.

A United Utilities spokeswoman said water transfers were under consideration "to address the challenges posed by climate change, population growth and protection of the environment".

"Any transfers would not reduce the resilience of supplies to existing customers," she said, adding that "there were no plans to take any additional water from Lake Vyrnwy beyond what is currently permitted".

Plaid Cymru's leader on Powys council, Elwyn Vaughan, said Thames Water needed to "get its house in order".

"[Almost] a quarter of London's water is lost through leakages, which is a pathetic situation," he said.

"They've also got a desalination plant which is actually turned off and, since 2006, they've promised to build a new reservoir near Abingdon and yet that hasn't been done.

"Sort those matters out and then we can talk business - but also pay a fair deal to Wales for this valuable resource."

Lake Vyrnwy was the largest artificial reservoir in Europe when work on the dam began in 1881

Independence movement YesCymru has launched a petition calling for a full debate on the issue in the Senedd, saying Wales should control its own natural resources.

Chairman Elfed Williams said: "We're happy to share our water with our neighbour but it should be of benefit to us - it shouldn't be London dictating."

Mr Davies, who is also MP for Monmouth, said the attitude was "narrow" and would "stir up divisions elsewhere where people would be saying 'why are we sending £1bn over to Wales for growth deals' for example, or 'why will Wales benefit from electricity that goes on to the grid as a result of Hinkley Point C".

He also said it raised questions about who would get the cash: "Would it go to the people in the area where the rain fell, or the people who live above the pipes?

"Is the Welsh government going to say 'hang on it's Wales so it's our water', or are the local authority going to say 'wait a minute it's nothing to do with Cardiff it fell in mid Wales so it's our water actually'.

"But when you start to think about the implications of this it doesn't work out at all because everyone else would want to charge [Wales for other things]... and at the end of the day we are one United Kingdom."

A Welsh Government spokesperson said: "Water resource management is a devolved matter.

"If any water trading options are considered, we will work with Natural Resources Wales nd the relevant water companies to ensure water resources are managed and used sustainably and do not have any detrimental impact on water supplies or the environment."