KINGFIELD — Selectmen took steps to plan an update to the current billing system for commercial and residential wastewater disposal.

The wastewater system is 30 years old, and pumps and pipes need repair and replacement. The system supports 267 customers, or about 20 percent of the town’s population.

Currently, households are charged $45.48 per quarter. Billing is based on an average four-bedroom home using 360 gallons a day. Some homes on the system have been converted into commercial rental units. Those commercial users pay $51.58 per quarter and are billed by “design flow” per unit.

Other customers, including restaurants, the Health Center, and other nonresidential users may not fall into a simple classification.

“Commercial units are all different, so right now, for instance, Longfellow’s (Restaurant) is being billed for eight user units,” Administrative Assistant Douglas Marble said.

Some seasonal commercial units may close, while others stay open, and the gallons of water coming into the unit do not match the wastewater  going into the system. Swimming pools, gardens and lawns skew any comparison, so selectmen decided the quarters with lowest use would be a better basis for setting an annual fee.

“If people are on the system, whether they use water or not, they need to contribute to the repair and upgrades to the system,” board Chairwoman Heather Moody said.

The current rate structure, executive director of Maine Rural Water, Steve Levy noted, brings in funds to pay for current problems but leaves little  for major repairs or reconstruction of the system.

“The average rate around the state is $400 per year,” Levy said.

Bryan Fitch, the wastewater system supervisor, said emergency repairs are very expensive, especially in winter. Kingfield customers also pay a much lower cost than others in Maine, according to Levy. He provided selectmen with a preliminary summary of the amount needed from sewer billings to cover basic expenditures.

“You will need $104,000, and you only have revenue of $25, 400,” Levy said at Monday night’s meeting. The remaining $78,600, he said, can only  be met by changing the rate structure. The 267 units on the system use 7,212,000 gallons of water, and Levy suggested selectmen look at two options for revised billing. The first includes an annual flat fee of $100 per quarter, returning an annual gross income of $26,700.

Usage would be billed at $ .00720 per gallon, for an estimated $51,900 annually. The second choice would include a flat annual fee of $150, or $40,050 of annual gross income. Per-gallon usage billed at $.00535 would generate revenue of $38,550. Both choices would provide the necessary $78,600 in revenue, Levy explained.

Selectmen chose not to vote on either choice, agreeing instead to meet again in October to continue the discussion. Residents will be notified that municipal representative will be doing an income survey to determine whether the system could qualify for a state Public Infrastructure Grant or a Community Development Block Grant. If the decision-making process moves smoothly, Levy projected selectmen could determine the new rate by January 2013.

In other news, selectmen appointed Maurice Lambert and Scott Hoisington to replace Kingfield Water Board Trustees Mark Robie and Mary Beth LaMont.