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Rainfall on watershed areas like the Koʻolau and Waiʻanae mountain ranges are collected in underground aquifers. The Board of Water Supply pumps water from these aquifers and delivers it to your home via water mains. Water enters a resident's home and is used for household activities and flushed down the toilet or drain.
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Untreated wastewater is conveyed through sewer mains from portions of Hawaiʻi Kai to Makapuʻu, then arrives at East Honolulu Wastewater Treatment Plant here the wastewater is disinfected using UV treatment.
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The entirety of the wastewater received at East Honolulu WWTP is disposed of through an ocean outfall that extends about 1/4 mile offshore near Sandyʻs Beach. East Honolulu WWTP treats about 3.5 million gallons of wastewater per day.
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Treated wastewater flows through an outfall pipe and is discharged into receiving waters (the ocean). The introduced wastewater can then mix with ocean water, be carried by currents to nearby coral reefs and possibly affect the health of these ecosystems.
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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.
- East Honolulu Wastewater Treatment Plant
- East Honolulu Wastewater Treatment Plant
