In an interview with the BBC the ex-chairman of Scottish Chairman Alan Alexander has urged ministers to consider mutualising the publicly-owned utility.

Speaking to the BBC Scotland's Politics Show, Mr Alexander said that Scottish Water was facing an investment backlog of up to 50 years. 

"I've said privately when I was there - publicly now - that, as Scottish Water became more efficient, it would become very, very attractive to politicians to stop putting money into it."

"I can see a position where politicians say 'let it be borrowed in the private market'.

"They can do that much more easily because the company is now efficient and because - and this is key - the real protection to the Scottish Water customer is regulation rather than ownership."

Although the Scottish Government has agreed to review the national water authority, the move is unlikely to lead to privatisation or mutualisation - First Minister Alex Salmond has already expressed "difficulties and doubts" about mutualisation.

Both the Conservatives and Liberal Democrats support mutualisation – the Tories would like to see Scottish Water run in a similar way to Welsh Water, which has no shareholders, is owned by a not for profit company and is run solely for the benefit of customers. Supporters of mutualisation say the change could save the taxpayer £180m each year.

Mr Alexander said Scottish Water could continue as it was, but added: "I would advise finding a way to make it possible for Scottish Water to maintain its drive towards efficiency without drawing money from the public purse.