Off-grid living in Washington: a property guide
Washington separates exemption from availability. A small domestic withdrawal may not need a water-right permit, yet the county still must address whether water is physically and legally available for the building proposal.
Water-right permit test
Four questions before a new right is issued
- 01Is water physically and legally available?
- 02Will the water be put to beneficial use?
- 03Is the use in the public interest?
- 04Will it avoid impairing an existing right?
A permit-exempt domestic well skips the ordinary permit application—not the state’s priority system, watershed rules, or the building authority’s adequate-water decision.
The finding that changes the purchase
“Exempt” describes paperwork. It does not promise supply.
Ecology explains that domestic groundwater use up to 5,000 gallons per day may qualify for the permit exemption. Multiple wells do not multiply the project’s exemption. New uses remain subject to senior rights, streamflow rules, watershed-specific restoration requirements, and additional local limits.
Identify the WRIA and watershed rule; obtain the county’s adequate-water requirements; ask Ecology about legal availability and mitigation; retrieve the well log; and independently verify construction, capacity, quality and seasonal reliability.
Local approval connects the water to the dwelling.
Washington’s Hirst guidance explains that counties must decide whether enough water is physically and legally available when approving a building permit that relies on a well. That makes the exact county, watershed, parcel and proposed use indispensable.
The written adequate-water determination path, required evidence, well/mitigation fees, building and land-use permits, trade inspections and occupancy endpoint.
Residential onsite sewage belongs at the local health office.
For design flows through a common point up to 3,499 gallons per day, Washington DOH identifies the local health officer as the approval authority. State rules set the framework; local management plans and site conditions supply the parcel answer.
Soil and site evaluation, design flow, initial and reserve area, water-source setbacks, designer/installer requirements, permit, final approval, maintenance and inspection duties.
Construction approval and placement approval are separate.
L&I reviews plans and inspects a tiny house built away from its destination, then issues its insignia. A tiny house built onsite goes through the local building department. Either way, local government decides where it can be placed and handles the foundation, installation and site permits.
Identify whether the product is a tiny house, tiny house with wheels, RV, park model, manufactured home or modular building. Obtain the approved plans/label and destination approval before paying for transport.
No statewide private-property shortcut establishes permanent RV occupancy.
The reviewed sources direct placement and use questions to the local building and land-use authority. RV registration or an L&I label does not itself approve a residential use, water source, sewage plan or year-round occupancy.
Separate storage, guest use, temporary construction occupancy, seasonal camping and permanent residence. Include dates, occupants, hookups and full water/sewage details in the written request.
State work inside the home and local work at the site divide.
L&I regulates specified manufactured-home alterations. Its guidance identifies the local building department as the installation inspector, while outside electrical work follows its own permit path. Zoning and site eligibility remain local.
Search labels and permits, investigate unpermitted alterations, confirm title status, local placement, foundation, utility connections, installation inspection and any required real-property conversion.
A defensible Washington file
Six approvals that must agree
Zone, legal lot, critical areas, shoreline/flood overlays, access and exact residential use.
Physical and legal availability, watershed rule, exemption/permit, construction, capacity and quality.
Local health jurisdiction, site/design approval, reserve area, installation and final signoff.
Classification, plans/label, destination criteria, foundation, installation and inspections.
Final building approval and any temporary or RV authorization with dates and conditions.
Easements, road duties, covenants, association instruments and utility service obligations.
Official-source notebook
What supports this guide
Reviewed September 26, 2026. State evidence is not silently stretched into local permission; open property questions remain open.
Uses, project limits, senior rights and local constraints
Physical and legal water availability for building approval
Local health authority for residential-scale design flows
Current Chapter 246-272A rules and local plans
Onsite versus offsite construction, insignia and local placement
State alteration permits and local installation inspection