A cesspool is a plain-and-simple hole in the ground — often fitted with a concrete cylinder that has an open bottom. Some have perforated sides. Raw waste from toilets is poured in. The substandard setup does not treat wastewater.

To the contrary, a cesspool’s drain-and-drip disposal concentrates wastewater in one location, often deep enough underground to cause groundwater contamination. Streams and ocean waters as well as beaches and coral reefs can also be tainted by this discharge of disease-causing pathogens and algae- causing nutrients.

These days, large-capacity cesspools, which serve multi-unit condos, homes with a rental unit or commercial properties with 20 or more people, should be nothing more than a repellent memory. Under the Safe Drinking Water Act, the U.S. Environmental Protection Agency required their closure by April 5, 2005.

Alas, many now-illegal cesspools remain, though it’s unclear how many. In the aftermath of the closure deadline, more than 3,400 large-capacity cesspools have been closed in Hawaii. In many cases, compliance has been voluntary. Still, any delay is maddening as the environment suffers.

In the latest case — 13 long years after the nationwide shutdown — the EPA recently reached a consent agreement with Kamehameha Schools through which the state’s largest private landowner pledges to see to it that any remaining large-capacity cesspools on its more than 3,000 properties are dismantled.

The federal agency put a positive spin on the settlement, calling it a “historic agreement” bringing Hawaii one step closer to the goal of eliminating all cesspools statewide. For its part, Kamehameha Schools rightly acknowledged “kuleana to steward aina.”

The EPA’s inspectors found an open large-capacity cesspool, which had been in use as recently as July 2017 on a Hawaii island property that the private, charitable trust leased to Hawaiian International Sporting Club Inc., which operated Volcano Golf Course and Country Club.

While the Safe Drinking Water Act allows up to $22,000-per-day civil penalties, topping out at $274,000, Kamehameha Schools will pay a penalty of less than half of the max because it’s committing to an independent inspection audit of properties on Oahu, Kauai, Maui Molokai and Hawaii island.

The agreement marks a first in which a business entity with property has come forward seeking to comb vast acreage in search of illegal cesspools. Kamehameha Schools is now poised to do the right thing. It’s concerning, though, that it took this long for the world’s eighth-wealthiest charitable foundation by endowment to shoulder this important responsibility for the sake of environmental and public health.

Kamehameha Schools, though, is not the sole financially flush offender. Last year, the EPA forged a fix-it agreement with the U.S. Navy, which dragged its feet on closure of three large-capacity cesspools at Pearl Harbor that served a total of about 160 people. In 2010, a Navy audit revealed that the Joint Base still had nine large-capacity cesspools. In 2012, the military closed six, but left three open.

Hawaii legislation enacted in 2017 requires replacement of all cesspools by 2050. In addition to large-capacity ones, the law targets the other type — small-capacity cesspools, which are often found in rural areas and typically handle waste for a single home. Even with three decades to go before the state’s deadline, the task appears to be a tall order.

That’s because there are an estimated 90,000 cesspools in Hawaii — far more than any other state. Nearly 50,000 are located on Hawaii island, nearly 14,000 on Kauai, over 12,000 on Maui, over 11,000 on Oahu and over 1,400 on Molokai. The widespread use dates back to Hawaii’s plantation era.

Back in 1992, the state put in place a ban on new cesspools on Kauai and Oahu, most of Maui, Lanai, and portions of Molokai and Hawaii island. Even so, until the ban was applied statewide in 2017, small-capacity cesspools were proliferating at a cringe-worthy pace of 800 new setups every year.

Much of the reluctance to opt for a modern septic tank or an aerobic treatment system, or connecting to a sewer system, has been tied to cost. The state Health Department, which regulates small-capacity cesspools, has estimated the statewide price tag at $1.75 billion, or about $20,000 for each fix.

In recent years, Hawaii has rolled out various incentives, such as a tax credit of up to $10,000. And in one case, it offered to cover half of the cost for upgrades in a Hanalei watershed area. But cash-strapped rural residents around the state have complained that they still cannot afford to make the switch.

In response, DOH and state lawmakers should rework current incentives with more attractive limited-time-offer carrots followed by tough enforcement of deadlines, including fines.

A tough stance is needed: at least half of the state’s identified cesspool inventory looms as a risk to our water resources due to proximity to aquifers (tapped for our drinking water), stream channels and watersheds.