To meet regulatory requirements and improve Lower Kula water quality, the Piiholo Water Treatment Facility was built in 1996. The site access road improvements and water treatment plant required three years to build at a construction cost of $15.7 million. The facility is located in the Makawao Forest Reserve adjacent to the Piiholo Reservoir.
Piiholo uses direct filtration to treat its water and uses chlorine as a disinfectant. Piiholo's average daily production is 2.5 million gallons per day.