Some people put on a trial scheme to reduce water usage have said they were being "forced" to take part, as they could not opt out.
The South West Water (SWW) trial involves two new tariffs including one where some customers pay a reduced rate during the winter months but more between April and the end of September, when when the company said "resources are under greater pressure".
Jacqui Rowe from Torquay said the trial was "very unfair", and added: "How can this be a trial, if it's compulsory?"
SWW said it was trying to "find fairer ways to charge customers, while protecting the natural environment".
'People are angry'
Torbay councillor for the Wellswood ward Hazel Foster said: "SWW needs to rethink this trial and cancel it.
"They are already on water meters, many are doing what they can to save water.
"Why should they be forced to go on this trial?"
New tariff trial
Those on the seasonal tariff will be given a lower rate for water between October and the end of March, but the cost will be higher for the rest of the year - during the summer months.
Customers on the summer peak tariff will get a lower than normal base price for water, which then increases once a usage threshold is met.
Kathleen Scrivener, from Torquay, said she felt the trial was unfair and had asked SWW to opt out, only to be told that was not possible.
"We're careful with water anyway," she said.
"We'll be paying more for our water next summer, when our neighbours - who are not on the trial - will be paying far less."
The trial is supported by Ofwat, which said: "The reality is that most customers - perhaps two thirds, but likely many more, will be better off."
The water sector regulator added: "It is vital that the water sector becomes more active and inventive in supporting customers who are struggling to make ends meet, as well as finding ways to help save water."
Paignton resident Lyn Mcgarey said she was was supportive of encouraging people to use water more efficiently and that she thought it was "a good idea".
"If people collected more water, you can really save quite a lot," she added.
'Pioneering'
SWW said the trial was "pioneering" and that it had been careful to exclude customers on social tariffs who may be struggling to pay their bills.
It also said customers who felt they could not be part of the trial due to financial concerns, moving house, or a health condition that would be exacerbated by being on the trial, should let the company know.
CEO Susan Davy said the company believed "everyone deserves a fair, transparent, and simple way of being charged for the water they use".
She said: "The introduction of our new customer tariffs is a direct response to what our customers have told us.
"We are launching two new tariffs as part of a trial to find better ways to charge customers based on the water they actually use.
"Water is precious and we are doing more than ever to secure resources for now and the future."
The trial is due to start on 1 October.