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Hawaii: Laws & Legal Considerations

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Rainwater catchment: unrestricted, and a primary water source for tens of thousands

Hawaii doesn’t just permit rainwater catchment, it’s a genuinely mainstream primary water source on the islands, not a supplemental backup.

RuleHawaii
Source water Rooftop catchment
Permit required for small systems No, for exterior systems used for outdoor irrigation up to 360 gallons storage
Larger/domestic systems Owned and operated by the homeowner; not regulated by the Department of Health or any other agency
Scale of use An estimated 30,000-60,000 residents statewide rely on rain catchment for their water needs (2016-2020 estimates)

Where to find it: the Hawaii Department of Health Safe Drinking Water Branch (health.hawaii.gov/sdwb/raincatchment) publishes safety guidance for domestic catchment systems.

A live 2026 legislative push

HB1728 HD1, active as of 2026, would require all Hawaii counties to allow rainwater catchment installation statewide, closing gaps in current county-by-county zoning that still restrict it in some areas. This is a pending bill, not enacted law; confirm current status if reading this later.

Concealed carry: shall-issue only since 2022, after decades as effectively no-issue

Hawaii’s transition to shall-issue concealed carry is one of the most dramatic legal shifts covered on this site.

RequirementDetail
Pre-2022 status Nominally 'may-issue' but functioned in practice as effectively no-issue for decades
2022 change The Supreme Court's Bruen decision (June 2022) forced Hawaii to become genuinely shall-issue: the issuing authority must grant a permit if the applicant meets all legal requirements
Issuing authority County Chief of Police
Firearm acquisition (separate from carry) Minimum age 21, a permit-to-acquire required for each purchase, fingerprinting and background check, plus a 14-day waiting period
2026 development A Supreme Court ruling (Wolford v. Lopez) held that a permit holder may carry onto publicly accessible private property unless the owner affirmatively posts a 'no firearms' sign or tells the carrier to leave

The most dramatic legal shift on the site

No other state covered here went from a decades-long, effectively no-issue system to shall-issue this abruptly. Hawaii’s carry law today looks nothing like it did before 2022, which is worth keeping in mind since older sources describing Hawaii’s gun laws may no longer reflect the current, post-Bruen legal reality.

Sources