Perspectives on Community Health: Board of Water Supply Waiheʻe Tunnel and Watershed Tour

On August 22, HIPHI’s Perspectives on Community Health Field Trips took us to Windward Oʻahu for the Waiheʻe Tunnel and Watershed tour. Perspectives trips are an opportunity for people interested in public health to step out of regular routines and join peers in learning about various organizations’ roles in community health. 

The Honolulu Board of Water Supply offers groups a unique opportunity to experience Oʻahu’s water system up close through guided tours of the Waiheʻe Tunnel and Watershed. Participants see and learn firsthand about our island water supply, the critical role of the watershed, and water conservation efforts. The tour is the only way for members of the public to see inside the Waiheʻe Tunnel, a 1,500-foot dike tunnel that provides fresh water to a section of Windward Oʻahu, from Kahaluʻu to Kailua.    

The Board of Water Supply limited access to the surrounding watershed area several years ago due to environmental and public health concerns. Our guide, Michele, explained that most of Oʻahu’s drinking water is groundwater: fresh water filtered through watersheds and stored in volcanic rock. Prior to the closure, Board of Water Supply staff would find piles of trash, bonfire remnants, and animal waste littering the area. These conditions risked contaminating the groundwater, eventually threatening the clean water supply for Windward Oʻahu. Limiting public access became necessary to prevent permanent damage.

Inside the tunnel is completely dark, with water flowing across the floor and dripping from the walls and ceiling. We learned more about how rain water from the mountain ridge above filters through rock for nine months, making its way into the tunnel system and eventually into our homes and businesses. Michele explained that some construction details remain a mystery, including the strings of old (now de-energized) electrical wiring and lights along the wet walls. 

Toward the end of the tunnel, the path splits into two sides: wet and “dry.” While the conditions in the “dry” room are similar to the rest of the tunnel, water pours from the ceiling in the wet room. Both sides end in large vault doors. Behind these doors is the mountain compartment that stores millions of gallons of fresh water. Our group had a chance to explore both rooms and spend time feeling the fresh water coming down straight from the source before making our way back outside.

To close the tour, we discussed some of the issues facing our water resources today, including climate change and the Red Hill crisis. While the answers to systemic issues can feel out of reach, we can all do our part to preserve water resources. Some easy ways to make conservation a habit include landscaping with water in mind,  locating and fixing water leaks, and following other household conservation tips. Residents can also report water waste, such as broken pipes and malfunctioning sprinklers, through the Water Waste Hotline.