NYAW supplies water from Long Island’s aquifers to 44,712 customers, most of them residential, in 22 square miles of southeastern Nassau, including all of Merrick, Bellmore, Wantagh, North Wantagh, Seaford and Massapequa Park and parts of North Merrick, North Bellmore and Levittown, according to the study. The company is a subsidiary of American Water Works Company, Inc., a multibillion-dollar, New Jersey-based company that is “the largest investor-owned United States water and wastewater utility company,” providing water services to 14 million people in the United States and Canada, regulatory filings state.

NYAW spokesman Peter Eschbach said that the average NYAW customer pays $480 for 72,000 gallons of water per year. “If you’re paying $300 or more a month it’s probably because you have an irrigation system or a large piece of property and a larger than average meter,“ Eschbach said.

Sansoucy’s study reports that the average Long Island American Water customer paid $657 for 160,000 gallons in 2010. The average Town of Hempstead customer, meanwhile, paid $132 for the same amount of water that year, the study states.

The disparity in the cost of water is greater among local fire departments. Susan Trenkle-Pokalsky, a Town of Hempstead spokeswoman, said that departments in the town’s water district pay $75 per fire hydrant per year. John Fabian, facilities manager of the Bellmore Fire Department, said that his department pays $628 per hydrant per year — on all 369 of its hydrants.

The state Public Service Commission, which regulates utilities, granted a NYAW request for rate increases in 2011. The increases took effect in 2012. Asked if NYAW is pursuing further rate increases, Eschbach declined to comment. He said he is “not aware” of any instance in which the PSC denied the company a rate increase, but that the “burden of proof” lies with NYAW to show that any increases are merited.

Private or public?