Water company United Utilities has admitted that it has eight full reservoirs despite enforcing a hosepipe ban in the North West.
The company has eight small reservoirs in Lancashire which were removed from the water supply system before water privatisation.
A spokesman said reconnecting them to the water supply system would also involve building costly new treatment works.
The spokesman said that such a project would not be value for money because “smaller reservoirs are the first to dry up anyway”.
But he did say the company does bear the cost of maintaining the disused assets.
“Any reservoir that’s in our ownership, whether it’s active or dormant, is still our responsibility to maintain,” he said.
He said United Utilities’ research indicated that customers would rather suffer a hosepipe ban than higher water bills.
“The amount of money needed [to reconnect the reservoirs] would triple customers’ bills,” he said.