Most of the year Maui's drainage problems are invisible. Then a Kona low parks over the island. The March 2026 storms were a hard lesson in what good site drainage is worth.
What March 2026 showed
- Maui saw some of the heaviest rain in the state, with nearly 50 inches over three days at Haleakalā's summit and parts of Kula.
- In Kīhei, floodwater and mud tore up South Kīhei Road. The county's own drainage master plan says that system was not built to carry large runoff.
- In Kula, residents blamed an undersized culvert for turning a stream into a torrent.
- Maui's Public Works director noted that infrastructure is designed for more typical storms, and that fully eliminating flooding in extreme events isn't realistic.
The takeaway: public drainage won't save every property. What you do on your own lot matters.
The toolbox
- Grading: the cheapest fix. Slope the ground away from the house on every side.
- Swales: shallow, vegetated channels that intercept and redirect sheet flow, especially uphill of homes on slopes.
- French drains: a gravel trench with perforated pipe, wrapped in fabric, that collects soggy-ground water and carries it away.
- Culverts: pipes under driveways and roads. Size them for big storms, not average rain, and keep them clear.
- Dry wells and detention: where soils allow, these hold water and let it soak in instead of sending it downhill.
- Downspouts and catchment overflow: route them somewhere safe, not against the foundation.
Rules to know
Grading that changes how water drains onto neighboring properties is one of the things that requires a county grading permit. Work in mapped flood hazard areas needs a flood development permit. See the permit guide. Call 811 before trenching for drains. See 811.
Keep the mud at home: runoff carrying sediment ends up on the reef. Good drainage and erosion control go together. See erosion control.
Find contractors on our driveways and drainage page. Landlords can line up storm prep with Maui Property Managements.