Mililani Town vs Waipahu
How do grading & drainage rules compare between Mililani Town, HI and Waipahu, HI?
Mililani Town has fewer restrictions than Waipahu.
Mililani Town, HI
Honolulu County
Mililani cut, fill, and trenching projects generally require a grading permit under ROH Chapter 18A, with drainage review to protect neighbors and downstream gulches.
View full Mililani Town rules →Waipahu, HI
Honolulu County
Waipahu land disturbing activities require grading permits under ROH Chapter 18A, which governs permits, bonds, inspections, and drainage review for all qualifying work.
View full Waipahu rules →Key Facts Comparison
| Fact | Mililani Town | Waipahu |
|---|---|---|
| - | - |
Highlighted rows indicate differences between cities.
Mililani Town FAQ
Do ADUs need a grading permit?
Many ADU projects require grading permits due to foundation excavation and drainage modifications around the structure.
Can I reroute roof runoff to my neighbor's lot?
No. Drainage must be directed to approved on-site locations or the public storm system, not onto adjacent properties.
Waipahu FAQ
Does adding fill for a small Waipahu addition need a permit?
Yes, if the fill or grading exceeds thresholds in Chapter 18A. Even modest grading associated with additions typically requires a grading permit, so confirm with permitting before starting.
Can my neighbor's runoff come onto my lot?
Grading permit drainage review is intended to prevent concentrated runoff onto neighbors. If your neighbor's grading changed drainage, document it and contact the Department of Planning and Permitting.
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