Selectmen have formally decided to seek a new policy for charging for sewer rates in the future.

Acting as Sewer Commissioners, Selectmen voted Tuesday to move away from the EDU rate policy with the intention of adopting a sewer rate that combines a fixed fee and water usage fee.

Currently, Wareham sewer users pay a flat annual $596 per EDU (equivalent dwelling units). A single-family home is charged one EDU, while a two-unit duplex is generally charged two EDUs. Businesses are scheduled similarly. For example, restaurants are charged one EDU per 12 seats; gas stations are charged one EDU per service island.

Tighe and Bond, a Pocasset-based engineering and environmental consulting firm, was commissioned by the town last May to study alternatives to the EDU system. Since then, Project Manager Michael Schrader has delivered reports at multiple public hearings on what the firm has learned from studying the data.

Schrader previously presented to Selectmen a "hybrid" model for charging for sewer usage. That system would charge a flat fee for all users with an additional flow-based fee for heavier users, leading to a more accurate distribution of the costs of the town sewer program.

"Everyone pays a minimum fee and those who use a lot pay more," Schrader said.

Schrader will now be preparing a plan that would show how to implement the hybrid model, what decisions would have to be made by Selectmen and what such a plan would cost the ratepayers.

Selectman Judith Whiteside said the vote signified a commitment to investigating how the new system would be implemented, but it did not mean that Selectmen would automatically adopt the new system.

Although the town plans to change the policy in the future, Selectmen voted to keep the current system at the $596 EDU rate for at least another year at their meeting on June 17.

Selectman Steve Holmes took issue with Schrader's claim that it would take six months to develop the plan.

Schrader replied that the schedule could be condensed depending on how often the board meets to discuss sewer issues and how much access he has to town officials.

"We can do this in an accelerated timeframe. Four months would be great if we can all work on this thing together," Schrader said.

If the plan took six months to create, it would be delivered to Selectmen in mid-March. The election to establish a new Board of Wareham Sewer Commissioners is scheduled to be held on April 1, 2015, with the Commissioners taking office on May 1.

Selectman Alan Slavin said he could see the process taking six months because there are usually difficulties conducting business over the holidays in November and December, combined with the fact that this process comes with a lot of tough questions.

"This is not a simple process. This is extremely complicated," Slavin said. "It's going to take a lot of work to get the numbers."