Customer complaints in the water industry in England and Wales have dropped for the third year running, a watchdog said today.
The Consumer Council for Water (CCWater) said the latest figures show a 4.5% decrease for the 2010-11 period compared with 2009-10.
But the council said this still meant there were 185,140 complaints last year and warned "some companies still have a long way to go".
CCWater chairman Dame Yve Buckland said: "It is good news for many customers that complaint levels are down and overall results look promising.
"We will continue to exert pressure on those companies who are underperforming until they match the best.
"CCWater is there to help water customers who have hit a brick wall with their complaint. In four out of five cases we step in to get the company to improve what it has done for the consumer."
The council said United Utilities, which serves the north-west of England, handled the most complaints - 39,000, which is an increase of 6.7% on the previous year.
The report said that while Yorkshire Water saw an increase in complaints of 23% last year, it still received very low numbers of complaints per customer served.
CCWater said companies with significant falls in complaints included Bristol Water (-41.6%), Wessex Water (-39.3%), Veolia Water Central (-35.8%) and Veolia Water East (-20.4%).
But the council said that despite a 30.5% reduction, South West Water still received more than the industry's average number of complaints.
It highlighted a number of companies that continue to have very low levels of complaints, including Portsmouth Water and Veolia Water South East.
It said there was "room for improvement in Wales", where Dee Valley Water's complaints rose by 24.6% following a 44% increase the previous year.
CCWater said that Dwr Cymru Welsh Water reduced its complaints by 17.1% but, when looking at the numbers of customers it serves, it still remains one of the poorer performing companies.
South East Water said its 9.6% drop in cases "reflects an ongoing positive trend, as South East Water has received 3,200 fewer customer complaints over the past three years".
Steve George, customer services director for South East Water, said: "This report underpins the steady and positive improvements we have made over the past three years to deliver better customer service.
"But we know we've got more work to do.
"We want our overall complaint numbers to reduce further and so we continue to invest in our people, and our processes, to try to deliver a better performance."