Each day, the city collects about 112 million gallons of wastewater from the toilets, sinks and drains of homes, workplaces and elsewhere, and funnels it to wastewater treatment plants. On the Windward side, the system stops just short of Kahaluu — and adverse public health and environmental effects tied to its absence are striking.

There are unacceptably high levels of fecal bacteria in Kahaluu Lagoon and channel leading to Kaneohe Bay, prompting the state to post warning signs that have remained in place for three years. The flow of raw sewage can degrade coral reefs, harm aquatic ecosystems and make people sick.

A Honolulu Hale temporary fix that involves cleaning the channel with dredging has been deferred for many years. And any proposal to expand sewer service to Kahaluu and other rural communities is expected to remain shelved for years. First, city officials say, they must contend with a 2010 federal consent decree that requires existing sewer system upgrades, with a total price tag of about $5.5 billion in 2010 dollars.

In the meantime, efforts must be stepped up in neglected Kahaluu and other communities without sewer service to phase out reliance on the primitive cesspool. Little more than an environmentally dicey hole in the ground, sometimes lined with bricks or concrete blocks, a cesspool simply holds untreated sewage, with the liquid percolating directly into the ground.

Only last year, Hawaii became the last state in the nation to ban construction of new cesspools when Gov. David Ige signed new rules related to wastewater disposal.

Put forward by the state Department of Health (DOH), the rules ban new small-capacity cesspools. The U.S. Environmental Protection Agency banned the large-capacity type, serving 20 or more people, a decade ago. The rules also include tax credits for property owners situated near water sources who convert existing cesspools into septic systems or other improved treatment units, or connect to a county sewage system. So far, unfortunately, the tax credits have drawn few takers.

In an effort to do the right thing for public health and the health of our natural resources, Hawaii should push to accelerate the phasing out of cesspools with more incentives and tougher legislation. Also, Kahaluu’s waters could surely benefit from an innovative cleanup effort echoing that underway on the Ala Wai Canal watershed.

Rhode Island, which has the second-largest number of cesspools in the country behind Hawaii, prohibited the construction of new cesspools in 1968. The phase-out, however, was sluggish until just two years ago, when the state adopted a point-of-sale provision requiring the scrapping of a cesspool system after sale of a property. The law allows either the buyer or the seller to pay for the upgrade, which therefore becomes part of the overall sale negotiation.

A similar idea proposed by Hawaii’s DOH three years ago was shot down when opponents contended that the price tag for the switch discriminated against low-income residents and expressed doubts about cesspool-related dangers. But with evidence confirming dangers continuing to pile up, it’s time to revisit a point-of-sale provision.

In Kahaluu, it’s likely that some of the area’s water pollution comes from agricultural runoff, while most of it seeps from more than 700 aging cesspools. Statewide, there are about 88,000 cesspools, releasing about 55 million gallons of untreated sewage into the ground every day. The vast majority pose a risk to our water resources, according to the DOH’s Wastewater Branch.

The risk is poised to grow with the prospect of more residential development in the Kahaluu area and elsewhere. Last month, the City Council amended the Koolau Poko Sustainable Communities Plan, which opens the door to allowing residences on 24 acres of land previously tagged for agriculture mauka of Kahaluu.

This pollution problem is overdue for a long-term mitigation vision, with the state and counties committed to backing it up. Surely more can be done to protect Hawaii’s nearshore waters and ecosystems.