Construction work in unincorporated Washington County, Mississippi requires a building permit; start with county Planning, Zoning & Engineering to identify the applicable process12. Inside Greenville, the city handles building permits and zoning; outside city limits, ask county Planning which zoning rules cover the parcel342. Septic permits throughout Washington County come from the Mississippi State Department of Health (MSDH)5.
At a glance
- Building permit
- Required for construction work; use county Planning or the applicable city building office126
- Zoning
- County records document zoning districts, but the complete current map and district schedule were not confirmed7
- Septic permit
- Required through the Mississippi State Department of Health for a new onsite system89
- Owner-builder
- A licensing exemption may cover work on your own residence, but it does not waive permits or other approvals10
- RV or tiny home
- Private-land occupancy rules are not confirmed; ask county Planning about the parcel2
- Septic soils
- Only 0.1% of county soils lack severe limits for a conventional drain field11
- Wastewater
- Gray water and other wastewater must go to sewer or septic, not onto the ground12
Who to call
Planning & zoning
Washington County Planning, Zoning & Engineering Department
Land use, development review, building policies, zoning issues, floodplain administration, engineering standards, and right-of-way, special transport and access permits
Septic permits
Mississippi State Department of Health, Division of On-Site Wastewater
Onsite wastewater applications, soil and site evaluations, permit recommendations, inspections and complaints
Contact details are copied from each office’s official page and were checked against it on October 11, 2026.
Off-grid gear
Going off-grid in Washington County means bringing your own water and power. The kit we’d start with:
- Water Crystal Quest Filter any source — well, rain, or creek — to drinking-clean.
- Power Bluetti Solar generators and home battery backup for living off the grid.
- Septic Soil percolation test kit Run your own perc test before paying an engineer — the first thing a septic office asks about.
- Water Well water test kit Bacteria, nitrates, hardness — know what the well on a parcel is really pumping.
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Do you need a building permit in Washington County, Mississippi?
Construction work in unincorporated Washington County requires a building permit; start with the Washington County Planning, Zoning & Engineering Department for the applicable building-permit process12. Inside Greenville, the city issues building permits before construction, alteration, demolition and land development begin; septic permits remain with MSDH313. We could not confirm the county’s building-permit triggers, application form, inspection sequence, certificate-of-occupancy rule or building-permit fees; ask county Planning what the project requires14. Mississippi’s owner-builder and agricultural-building exemptions concern residential-builder licensing and do not waive building permits, inspections, zoning approval, septic permits or utility requirements1015.
Who issues building permits in Washington County?
For unincorporated Washington County, contact the Planning, Zoning & Engineering Department at 662.334.2647 or rjohnson@co.washington.ms.us about building policies and development review2. County Planning also oversees floodplain administration and coordinates right-of-way, utility and access permits14. Ask county Planning which building, zoning, floodplain and county-access approvals the project needs because its published material does not provide a complete workflow14. Greenville handles its own building permits, while MSDH administers septic permits throughout Washington County39.
Does Washington County have zoning?
Washington County records document zoning districts, including A-1, C-3 and RE1, and county Planning handles zoning issues and land-use review72. For unincorporated Washington County, we could not confirm the complete current zoning map, district schedule, geographic coverage, minimum lot size, setbacks, lot coverage, building height or minimum dwelling size; ask county Planning which rules cover the parcel2. Inside Greenville, the city sets zoning through Appendix B of its ordinance; septic permits still come from MSDH413. County Planning oversees floodplain administration, but the published material does not state development thresholds or numerical standards16.
How do septic permits work in Washington County?
The Mississippi State Department of Health administers onsite wastewater permitting throughout Washington County, including inside municipalities, and a new system requires its Permit/Recommendation58. Submit the application, property documents, plot plan and fee; MSDH performs the soil and site evaluation17. The Notice of Intent plus Final Approval fee is currently $197.50, with an online processing fee and possible future changes18. If a sewer line is within 1 mile, MSDH requires the provider's rejection letter before continuing a septic application17. For a qualifying new single-family residence installing septic for the first time, the first residence on at least 2 acres or second residence on at least 5 acres may qualify for an inspection/final-approval exemption; the owner must still apply and install the MSDH-permitted system1920. Only 0.1% of county soils lack severe limits for a conventional drain field, so arrange the site evaluation before relying on a standard system11.
Can you live in an RV or tiny home in Washington County?
We could not confirm a Washington County rule allowing or prohibiting full-time RV living, temporary camping or tiny-home occupancy on private land. Ask the Planning, Zoning & Engineering Department for the parcel's zoning district and occupancy rules before buying or moving a unit onsite2. Septic rules still apply to alternative living arrangements: MSDH treats a house, trailer, manufactured home or similar single-family residence as a residential application, while developments with multiple trailers, cabins or RVs may need a commercial-development application19. A permanent water-meter connection requires a permanent sewage-disposal solution through sewer or septic21. Mississippi requires all wastewater, including gray water, to be piped to a central sewer or septic system and prohibits discharge onto the ground, into ditches or into bodies of water12.
Building a home in Washington County: steps in order
- Identify whether the parcel is in unincorporated Washington County or inside city limits, then ask the applicable planning office for the building-permit and zoning-approval process16.
- For a county-jurisdiction parcel, ask Washington County Planning about zoning, floodplain review and access requirements14.
- Determine whether public sewer is available; a permanent sewage solution is required before a permanent water meter can be connected22.
- If septic is needed anywhere in Washington County, submit the MSDH application, property documents, plot plan and fee before finalizing the house location517.
- Ask county Planning whether county-road access approval applies, and obtain an MDOT driveway permit for access to a state highway2324.
- If acting as your own general contractor, confirm that the owner-builder licensing exemption fits the project without treating it as a waiver of building permits or inspections10.
What should you check before buying land in Washington County?
Before buying unincorporated Washington County land, ask county Planning to confirm zoning coverage, floodplain status and road-access requirements71623. Washington County’s building-code opt-out status and adopted edition remain unconfirmed; ask county Planning which code applies25. Mississippi does not require a septic inspection solely for a property sale, but MSDH recommends one; an advanced treatment system also needs its tank inspected by a certified manufacturer’s representative or installer26. For land splits, MSDH generally defines a subdivision as 10 or more lots, but county ordinances may lower the threshold; public water can trigger Bureau of Public Water Supply review regardless of lot count27. Subdivisions exceeding 35 lots, or adding a new phase, require a wastewater feasibility study; ask MSDH and county Planning about review before dividing land272.
Watch-outs
- Construction work in Washington County requires a permit, but the county's published page does not state the triggers, inspection sequence or certificate-of-occupancy rules; ask county Planning before work begins114.
- A sewer line within 1 mile can redirect an MSDH septic application to the sewer provider unless that provider issues a rejection letter19.
- Only 0.1% of Washington County soils lack severe limits for a conventional drain field, so do not assume a standard septic layout will work11.
Sources
- Residential Application and Licensing Information, quoted and re-checked
- Washington County Planning, Zoning & Engineering Department (washingtoncounty.ms)
- Greenville: Sec. 2604. Building permits (Washington County), quoted and re-checked
- Greenville: Planning Development – City of Greenville (Washington County), quoted and re-checked
- On-Site Wastewater, quoted and re-checked
- Start Your Business in Mississippi — County and City Permits (Mississippi statewide rule), quoted and re-checked
- Washington County Board of Supervisors Minutes, August 6, 2012, quoted and re-checked
- On-Site Wastewater, quoted and re-checked
- On-Site Wastewater Online Application FAQ, quoted and re-checked
- Residential Laws and Rules Revised 2022, quoted and re-checked
- Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
- On-Site Wastewater Online Application FAQ — Sanitation and utility conditions, quoted and re-checked
- Greenville: On-Site Wastewater – Mississippi State Department of Health (Washington County), quoted and re-checked
- Planning, Zoning & Engineering, quoted and re-checked
- Residential Laws and Rules Revised 2022, quoted and re-checked
- Planning, Zoning & Engineering, quoted and re-checked
- On-Site Wastewater, quoted and re-checked
- On-Site Wastewater Online Application FAQ — Fees and process, quoted and re-checked
- FAQs and Answers — WasteWater, quoted and re-checked
- Notice of Intent: New Individual On-site Wastewater Disposal System, quoted and re-checked
- WasteWater Frequently Asked Questions, quoted and re-checked
- Wastewater Application FAQ, quoted and re-checked
- Planning, Zoning & Engineering, quoted and re-checked
- Mississippi Access Management Guide (Mississippi statewide rule), quoted and re-checked
- Mississippi Uniform Building Codes, quoted and re-checked
- WasteWater Frequently Asked Questions, quoted and re-checked
- Wastewater Application FAQ, quoted and re-checked
Written October 11, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.