The formula that determines the size of Kitchener residents’ water bills is a simple one: The more they use, the more they pay.

It’s long been considered a fair way to pay for the city’s water system while at the same time encouraging conservation.

But water use in Kitchener is now on the decline, even as the city grows – and that has municipal officials stressing the need for a change to how water bills are calculated.

All of the city’s water revenue is currently variable, based on the amount of water used. So are some of its costs.

Other costs – things like water main replacements and water treatment – are fixed costs.

“We save water, we keep saving – and as a result, our prices go up,” Coun. John Gazzola said in an interview.

And so, councillors heard Monday, the city is looking at changing its water rates so all customers pay a certain amount every month, regardless of how much water they use in that month.

Some portion of the bill would continue to be based on consumption levels, city officials say.

The goal would be to put the system in a place where changing consumption habits don’t leave the city with a shortfall, needing to find money elsewhere to cover needed repairs and other expenses.

City staff say the idea is still at a preliminary stage and they have yet to determine how much revenue they want to shift to a flat monthly rate, or what exactly that would mean on the level of an individual property.

“They haven’t given us anything to get our teeth into, so we really don’t know … what the impact (will be),” Gazzola said.

Coun. Paul Singh says he likes the thought of “better financial planning” from the water utility, but is concerned about significant increases to the average water bill.

“This new change can’t come at additional cost, on top of what they’re already paying,” he said.

Kitchener Utilities currently services 60,000 residential properties and 4,000 non-residential customers.

While smaller in number, the non-residential sites pack a disproportionate punch when it comes to consumption. According to city figures, they’re responsible for more than 40 per cent of water use in the city.

With reporting by Leena Latafat