HILO » The state has seen little participation in a program that offers tax credits to homeowners who upgrade from cesspools to alternative wastewater systems.

A state law providing $10,000 in tax credits for the cost of upgrading cesspools to a septic system or an aerobic tank system went into effect in January. Since then, the state Department of Health has only received 11 applications, The Hawaii Tribune-Herald reported Thursday.

There are 90,000 cesspools statewide, according to the health department. They release about 55 million gallons of untreated sewage into the ground daily.

“When you discharge to a cesspool, most of the water is concentrated on the bottom and you don’t really have soil treatments (for the wastewater),” said Sina Pruder, the department’s wastewater branch chief. “Because they’re dug deep, they discharge directly to groundwater.”

The law providing tax credits pertains to homeowners with cesspools located within 200 feet of the ocean, streams or a drinking water source. The total amount provided by the law is $5 million, and owners must submit applications by 2020.

Of the applications turned in so far, four have been from the Big Island, three are from Kauai and four are from Oahu.

“There’s no requirement to upgrade,” said Amy Cook, wastewater engineer for the department’s Hawaii County district office. “As long as your cesspool functions, you can continue to use it.”

The program was rolled out just two months before the state banned new cesspool construction across Hawaii. In March, Gov. David Ige cited reduction in sewage pollution as the primary reason for signing off on the ban.