The Wareham Fire District has approved a water rate increase, a move that Water Department Superintendent Andrew Reid said is necessary to operate a new treatment plant and keep up with inflation.

The rate change, which takes effect July 1, will increase a user’s water bill by 52 percent. The rate was approved Thursday night by the Board of Water Commissioners. Currently, users pay $.0051 per gallon. Under the new rate, users will pay $.0078 per gallon.

According to officials, the current bill for someone using 37,400 gallons of water in a six-month period is $193. That’s close to the amount of water an average household uses, said Reid. With the increase, that number will be $293.70. The district bills users twice a year.

Reid said that rate increase will bring what Wareham users pay closer to the average state water bill, which is $297 bi-annually.

“The district understands this change will be a burden and it has spent a lot of time developing a rate that will be reasonable,” said Reid.

The increase is necessary for a few reasons, he said. Among them is the need to fund an estimated $300,000 in operating costs for a yet-to-be-built water treatment plant.

Approved by voters at the district meeting last year, the $12.5 million water treatment plant will lower amounts of manganese and iron in the drinking water supply. Officials said the district was under pressure from the Massachusetts Department of Environmental Protection to lower the manganese levels on its own or face a compliance order from the state.

The operating cost includes paying for chemicals, sludge removal, electricity and more, said Reid. He stressed that the $300,000 was a rough estimate because the plant is yet to be constructed. Reid said the figure could be much lower once the plant comes on line.

Regarding the 52 percent increase, Reid said the average annual bill for users still falls below state and federal guidelines for affordability.

Reid said the U.S. Environmental Protection Agency recommends an annual water bill be 2 percent of median household income. For Wareham, which has a median household income of $59,000 (according to 2010 U.S. Census data), the bill should be $1,180 or less.

Reid noted the state recommends an annual bill be between 1.25 and 1.5 percent of median household income, equaling $737 to $885 annually. When the new rates take effect, the annual water bill for an average user will be $587.40.

The Wareham Fire District supplies water and fire protection for much of Wareham. A separate Onset Fire District performs the same function in Onset. Separate from the Town of Wareham, the Fire District is overseen by an elected five-member Prudential Committee and three-member Board of Water Commissioners. The district sets the water rates and allocates funds for the Wareham Fire Department.