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Water and sewerage companies in England have organised 36,000 switches of supply for small businesses since new rules came into effect this year.

Big companies using more than five million litres a year have been able to switch supplier since 2011.

That power was given to the remaining 1.1 million small and medium sized businesses in April this year.

The aim was to encourage competition and bring pressure on suppliers to lower prices and improve services.

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However, fewer than 36,000 firms have actually switched supplier.

Businesses with large premises may have more than one supply point for water or sewage, and the industry counts the number of supply points that are switched, rather than the number of businesses involved.

The new market for enabling businesses to change their water and wastewater suppliers is run by Market Operator Services Limited (MOSL).

Chris Scoggins, chief executive of MOSL, acknowledged that the process of encouraging switching was still in its very early stages.

"While it is early days, we are already seeing some positive developments, with customers of all sizes engaging in the market," he said.

"That's great news, but there's still much to do."

The water regulator, Ofwat, said: "In addition to those who have switched, we have heard that many others have agreed new deals with their current retailer."

"More needs to be done however; comparing offers is still not as easy as it needs to be and we have told retailers they must remedy this," added its chief executive Cathryn Ross.

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When a company switches its water supplier or sewerage firm there is no change to the pipes supplying its land or premises, or to the water or waste flowing through them.

They are still owned and controlled by the privatised regional monopolies in England, or the 16 small, water-only, suppliers which have always been privately owned.

The business customers sign a new contract for water supply, sewerage services, or both, with one of the 22 companies who have set themselves up as specialist business-only water retailers.

Some are simply existing water firms trading under a different name but 10 are new entrants to the industry.

They all have the right to sign up new business customers in any part of England, send them bills, and to supply them with water or take away their wastewater.

The existing water and sewerage firms operate as wholesalers to the new suppliers, while continuing as before with their business customers who have not switched.

There are no plans in England to let householders switch their water utility providers.