The Town of Wareham is considering whether to move from its current flat fee for sewer usage and instead bill residents for the amount of water they use.

"What we're saying with this proposal ... is to base [sewer bills] purely on water consumption," said Water Pollution Control Director Guy Campinha.

Currently, residents are charged a flat fee of $596 per year based on how many "EDUs" -- or equivalent dwelling unit -- a property contains. For example, a single-family home is charged one EDU, an apartment building with three units would be charged for three EDUs.

The Selectmen on Tuesday voted to allow the town administrator to enter into an agreement with Pocasset-based engineering and environmental consulting company Tinge & Bond to conduct an evaluation of the way Wareham bills residents for sewer and water.

"It's a way to apportion the costs in proportion to usage," project manager Michael Schrader of Tinge & Bond said of the potential change. "This is an evaluation to give you the tools to make a decision."

The study would go back five years, would not exceed $17,500, and would be paid out of the Water Pollution Control Facility's budget for expenses.

"We've been trying to do that for a long time" Selectman Patrick Tropeano said of the proposed change. He pointed out that in some cases, a single person living in a home will pay as much as homes with multiple residents.

The company is proposing that it analyze past revenue generated under the current system in order to determine what the best course for the future.

"Some people are going to pay more, some people are going to pay less, but it's in direct proportion to usage," said Schrader.

Selectman Steve Holmes questioned whether or not the company has worked with a community such as Wareham in which the population -- and thus the water usage -- fluctuates drastically based on the season.

"I'd have to look back" and check company records, Schrader replied.

Holmes pointed out that charging ratepayers in proportion to usage would encourage people to be more aware of the environmental impact of their water usage.

The consensus seemed to be that it is a change that is long overdue.

"We have to move," said Selectman Judy Whiteside. "We're paying for the gathering of information, and when we have that information, we can share it with the public."