Island planning · reviewed September 3, 2026
Hawaiʻi Island catchment water planning
East-side rainfall and west-side dryness change how much storage and maintenance a catchment home needs. Plan roof-to-tap before replacing equipment.
Island context
What changes on this island
Island contextMany Hawaiʻi Island homes use catchment; HELCO electricity rates affect pump operating cost.
Rainfall variabilityHilo-side rainfall patterns differ sharply from Kona-side dry spells—size dry-day storage accordingly.
Health boundaryMaintenance and testing reduce uncertainty but do not replace DOH guidance or laboratory results.
Statewide tools, island-aware next steps. These calculators and checklists work statewide—use the county research launcher for parcel-specific records.
Hawaiʻi Island guideCatchment, rock, lava-zone records, and last-mile freight.Tank sizing calculatorStorage gap, collection, and pump electricity.Maintenance budgetFilters, UV, cleaning, and reserves.Buyer checklistRoof-to-tap inspection path.Property researchHawaiʻi County parcel and permit records.