AUBURN – Allen Theriault doesn’t charge for the water he hauls to fill swimming pools all around Central Maine, and neither does anyone else.

The cities don’t charge him for the water he pulls from Lake Auburn, either. All the same, he writes them a check each year for the right to use the lake.

The water is free. It’s the delivery charges that add up.

“We just charge for the transportation and the city charges for keeping the water in good shape,” Theriault said. “People wonder why it costs so much to fill their pool. They ask why the water’s so expensive. And I say it’s not, but transportation is.”

Theriault’s is one of three local companies that haul untreated water in bulk, taking it from Lake Auburn, Sebago Lake and other nearby ponds and lakes.

With oil prices rising, Theriault and his competitors in the bulk water delivery business are having a tough time. Theriault is running one truck this summer, a 7,000-gallon tanker. He mothballed his second tanker before the summer’s hauling season started. It cut his capacity in half.

“But it cut my expenses even more,” he said. “With having to pay for maintenance and diesel for the second truck and another driver, I would have been losing half my income, anyway.”

He charges about $200 per 7,000-gallon tank. That’s enough to fill the average household pool about one-third of the way. Average-sized pools demand three or four trips; bigger pools can require as many as 10 trips.

Demand for his services and the fresh untreated water he brings in directly from one of Maine’s lakes is down this year.

“People have been holding back because of the rough winter they had,” he said. “They’re not putting in new pools, so they don’t need water to fill those pools. Plus, it’s been pretty rainy. And weather like that, people don’t think about their swimming pools.”

Combined, the three companies pull an estimated 3 million gallons of water from Lake Auburn during a season, much of it for use in area swimming pools.

It’s a pretty small amount, according to Mary Jane Dillingham, water quality manager at the Lewiston-Auburn Water Quality Management.

Lewiston and Auburn use twice as much water daily as the tankers pull per year, but water use goes up in the summer. On Tuesday, for example, residents in the cities used more than 9 million gallons of water.

In all, it would take a fleet of 1,000 tankers like Theriault’s to match the daily drain on Lake Auburn.

“They let more drain away on the outlet each day than we take in an entire summer,” said Warren Hood, of bulk water firm A. Hood and Sons. “We’re not taking much, not at all.”

Hood, operator of a fleet of Splash! tanker trucks operating all over central Maine, pulled 2.17 million gallons out Lake Auburn between May and November 2007.

Theriault, with his two 7,000-gallon tankers removed 580,000 gallons during the same time. A third supplier, Andy Michaud, removed 47,250 gallons with a single 3,500-gallon tanker.

Each pays a $25 per truck fee at the beginning of the summer to register with the Auburn Water District. Each settles up at the end of the year, paying 30 cents for each 1,000 gallons they’ve hauled.

Combined, the three companies paid $829 to the water district last year for the right to use the lake.

“It goes for resource protection, for keeping the water clean to start with,” Dillingham said. “They can just put the water in, untreated, and not have to add anything else to it. That’s what they want, and that’s what they’re paying for.”