Paʻalaʻa Kai Wastewater Treatment Plant

  • Drinking water is sourced from the aquifers in areas of the Koʻolau & Waiʻanae Mountain ranges and pumped to your home via water mains.

  • Untreated wastewater is conveyed through sewer mains from Waialua to Haleiwa on the North Shore of Oʻahu. The wastewater then arrives at the Paalaa Kai Wastewater Treatment Plant where it receives secondary treatment.

  • The entirety of the wastewater received at Paalaa Kai WWTP is disposed of via 10 injection wells located at the facility.

  • Treated wastewater flows through groundwater toward the Pacific Ocean, where it emerges often through the reef itself, via openings that present as direct pathways from the wastewater treatment plant to the reef.

  • Oʻahu's Drinking Water Sources

    Oʻahu relies solely on underground water sources for drinking water which are all dependent on three natural elements: northeast trades, high mountain ranges, and the island's geological landscape. The NE tradewinds drive clouds filled with moisture inland, the high mountain ranges (Koʻolau mountains and Waianae mountains) capture and force moisture-filled clouds to higher elevations which causes rainfall on watershed areas. The Hawaiian Island geological landscape serves as a natural filter and underground storage system of water. Rainwater percolates into the earth, filtered by volcanic rock, and stored in aquifers. The aquifers are an underground freshwater reservoir storage from which the Board of Water Supply sources water to deliver to homes. Water is pumped from a network of shafts, water tunnels, and many wells located all over Oʻahu, (except for the North Shore area) and conveyed to homes through mains, booster systems and reservoirs.

    Oahu's Drinking Water Sources
  • Paʻalaʻa Kai Wastewater Treatment Plant Facility
    Paʻalaʻa Kai Wastewater Treatment Plant
  • Service Area
    Service Area

Do You Know What Happens After You Flush?