Nestled between the majestic Koolau cliffs and the vast Pacific Ocean, the town of Hauula, Oahu, faces a hidden environmental threat. Hundreds of homes in this picturesque locale rely on cesspools for wastewater disposal, a system now under increasing pressure from rising sea levels and climate change.

Unlike urban areas connected to municipal sewage systems, Hauula's reliance on cesspools poses unique challenges. These underground pits collect wastewater from homes, but their efficacy is being compromised by the encroaching ocean. Rising seas erode the coastline, pushing groundwater closer to the surface and facilitating the mixing of cesspool effluent with the water table. This contaminated water then flows into the ocean, posing significant health risks.

Community members, like Dotty Kelly-Paddock, president of the Hauula Community Association, are acutely aware of the problem. "We deserve proper sanitation," she emphasizes, highlighting the community's concern for their children's health and the urgent need for change.

Hawaii leads the nation with 83,000 cesspools, approximately 20% of which are located within a mile of the shoreline. While a 2017 mandate requires the removal of all cesspools by 2050, the scale of the undertaking and the associated costs present significant hurdles. Scientists warn that the effects of climate change will only intensify the problems associated with these outdated systems.

Cesspools became widespread across the islands during periods of rapid development and can be found in diverse locations, from historic plantation towns to affluent neighborhoods like Honolulu's Black Point. While the ground is intended to filter bacteria and pathogens from the wastewater, rising sea levels and increased storm intensity are disrupting this process.

Coastal erosion, exemplified by last year's house collapse onto a North Shore beach, directly exposes cesspool contents to the ocean. Inland, the proximity of cesspools to aquifers leads to contamination of groundwater, which then flows into the ocean through springs. A 2021 study on the Big Island demonstrated the rapid movement of contaminants from shoreline cesspools to coastal springs, taking as little as nine hours. The same study revealed that bacteria levels in the ocean near the majority of sampled homes exceeded state health standards.

Health officials warn of the risks associated with sewage exposure, including gastroenteritis, skin infections, and conjunctivitis. A 2020 Hawaii Department of Health report highlighted the potential link between cesspool contamination and the state's elevated rate of MRSA infections, a type of antibiotic-resistant bacteria.

Regular water quality testing conducted by volunteers with the Surfrider Foundation consistently reveals high bacteria levels in areas with numerous cesspools. While establishing a direct causal link remains challenging, the correlation underscores the need for addressing this critical environmental issue.