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Idaho: Laws & Legal Considerations

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Rainwater harvesting: unrestricted

Idaho places no permit requirement or volume limit on residential rainwater harvesting.

RuleIdaho
Source water Rooftop or other catchment
Permit required No
Volume limit None at the state level
Permitted uses Non-potable, typically irrigation and similar uses

Where to find it: the Idaho Department of Water Resources (idwr.idaho.gov) administers water law generally.

Water rights: prior appropriation with a distinctive conjunctive-management layer

Idaho has followed prior appropriation since the Idaho Territorial Legislature adopted it in 1881, later written into the state constitution. What makes Idaho’s system distinctive is how it treats the connection between the Snake River and the aquifer beneath it.

ConceptHow it works in Idaho
Basic rule The earliest-dated beneficial use of a water source holds first claim during a shortage
Conjunctive management The Eastern Snake Plain Aquifer is hydraulically connected to the Snake River itself, so state regulators administer surface water and groundwater rights as one integrated system when groundwater pumping affects senior surface rights
Priority order Because surface-water delivery systems predate groundwater pumping in most of the state, surface water users generally hold seniority over groundwater users

Where to find it: the Idaho Department of Water Resources administers conjunctive management under IDAPA 37.03.11.

Permitless carry from age 18

Idaho has allowed permitless concealed carry since 2019, joining Arkansas, Indiana, Louisiana, and Mississippi as one of the permitless-carry states covered on this site with an 18, not 21, minimum age.

RequirementDetail
Standard Permitless carry, concealed, for any U.S. citizen 18+ legally eligible to possess a firearm
2019 change Idaho Code §18-3302E lowered the permitless age from 21 to 18, effective July 1, 2019
2020 expansion HB 516 removed the residency requirement and the inside/outside city-limits distinction, extending permitless carry statewide to all eligible U.S. citizens and active-duty military, effective July 1, 2020
Optional license Remains available through county sheriffs for reciprocity in states that don't recognize Idaho's permitless standard

Idaho's own internal consistency

Idaho’s 18-year-old permitless-carry threshold matches its own age for open carry and long-gun purchases, a single consistent age across all three, which isn’t true of every state covered on this site (Tennessee, for example, sets 21 for its general permitless standard but carves out 18 specifically for active-duty or honorably discharged military).

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