Planned rate changes to offset rising costs could more than double the water and sewer bills of some Calvert County homes and businesses while decreasing the charges paid by others, according to figures provided to county commissioners this week.

While the commissioners appeared committed to raising the overall fees, they are still debating whether rate increases should take place in one increase next summer or be phased in over two to five years.

At a Tuesday work session, the commissioners asked staff members to plan a series of increases over a period of up to five years. The issue is scheduled to go before the Board of County Commissioners again late this month and then go to public hearing next month.

The size and scope of rate adjustments will depend on how they are structured. The county is considering three methods of charges: a system-based rate approach, a one-rate approach or a combination of the two.

Calvert has nearly two dozen public water and sewer systems, each serving a different town center or other major development.

The system-based alternative requires that each system sustain itself, with rates calculated so that the users pay all service costs within their particular system. Under that approach, changes in quarterly sewer and water rates would range from a $234 increase in Industrial Park to a $13.83 drop in St. Leonard.

"This method is more beneficial to the larger systems," said Terry Shannon, the county's director of administration and finance.

Under a one-rate system, all users would pay a uniform countywide charge, with system-specific costs and revenue spread evenly across the county. This would mean that a gallon of water in Huntingtown would cost the same as a gallon in Prince Frederick, Shannon said. Repair costs of one system would be absorbed by rate payers across the entire county.

"This method would be more equitable and more efficient to maintain," Shannon told the commissioners. "But it could appear that one system is subsidizing another system."

Charles and St. Mary's counties use the one-rate system.

The one-rate approach also would mean wide swings in the financial impact on different customers -- ranging from a quarterly increase of $141.30 in some areas of the county to a decrease of as much as $96.94 in other places.

A combination of the two options -- which appeared Tuesday to be the preference among county staff members -- would set a fixed countywide rate for water and sewer services and then charge a system-based fee to fund the debt service and other costs associated with building or expanding each system.

Residents' rates would be based on use of up to 10,000 gallons of water per quarter, a volume that reflects the current quarterly average of 8,000 to 10,000 gallons per household.

Shannon's suggestion that the rate changes be fully implemented by Oct. 1 was rejected by the commissioners.

She also proposed a two-part phase-in over the next 11 months that would introduce some increases by Dec. 31.

The commissioners rejected this proposal, saying they did not want to impose the increases during the holiday season.

"We're doubling their rates," said Commissioners President David F. Hale (R-Owings). "Can we take these rates and spread them over three or four years?"

Hale also said that upcoming sewer and water bills should begin notifying customers of the planned rate increase well before it takes place.

The additional revenue would help pay for system improvements. Those include pipe and tank replacements, meter installations across the county and new wells and sewer upgrades, said Dan Williams, chief of the county utilities bureau.

The Water and Sewer Fund -- which is run like a private business -- does not rely on tax dollars to provide its services.

"It's intended to be a self-sufficient fund," Shannon said.

But its rates have not changed for years despite annual increases in operating costs. Instead, money was drawn from its reserves to make up cost increases.

"Rather than increase rates, there were sufficient reserves so a rate increase was deferred," said Shannon.

But the commissioners now want more regular rate reviews to prevent drastic increases in the future.

"It's been 20 years since we've done this," Hale said. He proposed setting up an annual process to make future boards consider water and sewer rates.

"I don't think we should ever have been put in this position," said Commissioner Gerald W. Clark (R-Lusby).