Welsh Water: 'Too costly' for Wales to supply drought-hit England
Moving water from Wales to drought-hit southern and eastern England would be too costly and damaging to the environment, says Welsh Water.
Nigel Annett, the firm's managing director, told BBC Wales it was possible but the cost was "truly prohibitive".
At a drought summit last month calls were made for better interconnectivity between water companies.
On Monday seven English water companies announced hosepipe bans from 5 April.
The companies said the water restrictions followed two unusually dry winters which have left reservoirs, aquifers and rivers below normal levels.
In June 2011 London Mayor Boris Johnson raised the idea of moving water supplies from Wales and Scotland to areas of shortage in the south and east of England.
Last month The Institute of Civil Engineers (ICE) said it wanted changes in approach to water management, including improved interconnectivity between water companies.
At the time the Welsh government said it had not been approached by the UK government for water to help ease the drought.
But it added that the people of Wales should receive proper value for "this vital resource".
However Mr Annett told BBC Wales: "Certainly from an engineering point of view it's probably possible, but the cost is truly prohibitive."
Mr Annett said the idea had been last considered seriously in 2006.
"In 2006 the estimate was it was 10 times more expensive than many of the other options and the environmental impact is truly enormous," he said.
"I would dearly like to be able to sell water to somebody else, make a big fat profit and pass that back to our customers in the form of lower bills.
"But water is a very heavy product. The cost rises very, very sharply once you start moving it."
Mr Annett said any large-scale transfer from Wales to other parts of the UK would involve lots of pumping.
"We all know what's happened to energy costs, so I suspect those companies and those regions that are short of water, will find other solutions to the current problem," he said.
In Wales water levels in most reservoirs and rivers are almost at full capacity.
Some reservoirs already supply the city of Birmingham and parts of Cheshire and Merseyside.
Alun Attwood, water resources manager of Environment Agency Wales, said the idea of whether there was enough water in Wales to support a national water grid, or large-scale transfers across the border, was something that needed to be considered in much more detail.
Mr Attwood said: "Our recent forecast suggests that because of the limited water available in Wales - and already some rivers are at their sustainable limit in terms of how much water can be taken from them without affecting the environment - it means that there might not be enough water to provide surplus water, or further water to England."