Washington CountyMarket Report

These records retain their existing review-only status and are not added to the land or house pricing samples.

1. Establish jurisdiction and the approval path

Confirm city limits, current ETJ/interlocal jurisdiction, vested rights, recorded restrictions and utility service before applying county standards. The Subdivision and Development Regulations, approved March 31, 2026, address county-jurisdiction subdivisions outside city limits. Sections 1.04 and 5.03 govern coordination with municipalities. A pre-application meeting and sketch are required for a final plat, replat or subdivision cancellation; the meeting is optional but recommended for a minor or amending plat (§3.01).

A minor plat is not a general four-lot exemption. Section 4.01 limits the route to qualifying 1–4-lot divisions, requires direct public-road access, allows no new roads, and looks at cumulative daughter-tract splits after December 31, 2009. Check parent-tract history before treating a new purchase as a fresh four-lot opportunity.

2. Exemptions: more than ten acres means more than ten

Section 2.02 lists conditional platting exemptions, including a division where every lot exceeds 10 acres, qualifying agricultural uses, and certain family transfers. Exactly 10.000 acres does not meet the listed greater-than-10-acre test. An exemption also depends on the division and road/public-use arrangement; acreage alone is not enough. The county states that exemptions do not remove frontage, setback or lot-area requirements and asks for a courtesy notification with a survey or sketch. Obtain a written county determination of the proposed arrangement before underwriting an exempt split. Loss of the qualifying use or exemption can trigger platting obligations for the parent area. An agricultural tax valuation is not itself a subdivision approval.

3. Water and septic determine the lower end of the lot mix

The current 2025 OSSF order, approved by TCEQ July 17, 2025, §9(B), sets minimums for parcels created on or after its effective date that are not served by centralized wastewater:

• 1.0 acre if served by a public water system.
• 1.5 acres if not served by a public water system.

These minimums do not guarantee septic suitability or a usable building envelope. Check soils, well and water-body separations, easements, drainage and disposal area with a qualified designer. The county's still-posted 2016 guidance is stricter in some wording about private wells and multiple habitations; obtain Environmental Health's interpretation for mixed public-water/private-well service or multiple dwellings rather than assume that the older handout controls the 2025 order.

Each new, altered, repaired or extended OSSF needs a permit regardless of acreage (§9(A)). Surface-spray edges require at least 25 feet from the listed buildings, property lines and other improvements, and 75 feet from listed waterways and ponds (§9(P–Q)). More than one dwelling/RV per acre, commercial/institutional uses and multi-unit residential development trigger additional loading and reserve-area requirements (§9(J)); do not treat guest houses or RV sites as free extra density. The subdivision application requires an OSSF suitability study, or applicable public water/wastewater will-serve letters (§3.02).

4. Frontage, setbacks and infrastructure footprint

For rural subdivisions, all lots are at least one acre and must have 60 feet of road frontage. Lots front a public road unless within an approved private subdivision. Rural building setbacks are 50 feet from TxDOT right-of-way, 25 feet from other road right-of-way, 10 feet at sides and rear, and 25 feet on a corner lot's side road (§5.01). These are county minimums; other applicable restrictions may be stricter.

Utility easements also consume usable layout space. The posted regulations contain differing road-adjacent widths: §5.01 states 15 feet while §5.02 states at least 20 feet for easements contiguous with public right-of-way. Have EDS confirm the controlling width before fixing lot lines. Do not resolve that inconsistency by assuming the smaller dimension.

Lots below one acre fall into the urban category, with public/community water and wastewater, storm sewer rather than open ditches, and separate lot standards. A sub-acre concept is therefore a different infrastructure strategy, not simply a tighter rural septic layout.

5. Roads, access and developer obligations

Road dimensions and pavement design depend on classification under the March 31, 2026 Design and Construction Standards Manual, §4. Existing road frontage can require additional right-of-way and proportionate improvements under subdivision §6. Verify legal access, measured frontage, road classification, driveway locations, culverts and off-site improvements before pricing the tract.

Private rural roads generally must meet public-road standards unless the entire subdivision meets the stated exemption; private maintenance does not mean low-spec construction (§7). The county does not pay to construct or maintain private roads. Where construction surety applies, subdivision §3.03 specifies 120% of the estimated improvement cost, subject to county approval. Carry engineering, drainage, utility relocation, surety and long-term maintenance in the acquisition budget.

At 20 or more rural lots, fire suppression requirements become material. Manual §11 includes subsequent phases and requires fire-suppression ponds for qualifying subdivisions without a potable system incorporating hydrants. Plan the full buildout, not just the first phase. Traffic worksheet requirements begin at 100 single-family lots under manual §5.01; county review can require a traffic study for special circumstances below that threshold.

6. Drainage, floodplain and permits

Manual §§6–7 require a site-specific drainage design with no net increase in runoff rates and no negative impacts; most projects need on-site detention. Detention outflow is checked against predevelopment 10-, 25- and 100-year 24-hour storms (§6.03). Reserve real land for detention, outfalls, access and maintenance rather than assigning every gross acre to sale lots. The county does not maintain stormwater facilities; a pond maintenance agreement is required unless an alternative is approved (§6.05).

Do not import Montgomery County's detention assumptions. Washington's optional 0.55 acre-foot per modified-cover acre coefficient method is specifically for small developments, less than 5 acres commercial or 10 acres residential, with total future development limits (§6.04). It is not a blanket detention rate for a 75+ acre acquisition. Have the engineer and county confirm the applicable method and final storage.

Environmental Health administers floodplain development review in unincorporated areas. Obtain authorization before floodplain-related construction or development. Subdivision applications on land within FEMA's 100-year floodplain require a flood study (§3.02); manual §12 calls for Floodplain Administrator compliance with the final plat. Review the effective FEMA map and parcel-specific grading, access and drainage; the report's county floodplain overlay is a screening aid, not a parcel determination.

The county EDS permit guide lists culvert permits for driveways fronting county-maintained roads and permits for utility work in county right-of-way. Its statement that unincorporated areas do not require general building/electrical permits does not remove subdivision, OSSF, floodplain or other applicable approvals.

7. Acquisition and lot-mix decision checklist

• 1–1.49 acres: do not assume a well-and-septic product works. Confirm public-water commitment, capacity, taps and OSSF suitability before assigning yield.
• 1.5–10 acres: passing an acreage minimum still leaves platting, access, drainage, septic and net usable-area constraints. Model a road-and-infrastructure budget, not gross acres divided by lot size.
• More than 10 acres: evaluate the conditional exemption and road arrangement with EDS; larger lots do not eliminate OSSF permits or floodplain review.
• Before the feasibility period ends: obtain the survey and parent split history, jurisdiction confirmation, concept layout, utility commitments, septic suitability, floodplain/drainage review, road and fire-suppression scope, fees and engineer's cost estimate.

Verified county contacts

• Engineering & Development Services / County Engineer: 979-277-6275 · wcrboffice@washingtoncountytx.gov · subdivision intake, plat/plan review and road access.
• Environmental Health: 979-277-6290 · OSSF and unincorporated floodplain review.
• Addressing & Mapping: 979-277-6279 · road names and 911 addressing.

Current location: 3650 State Highway 36 North, Brenham, TX 77833. Use current EDS contacts rather than the old courthouse-annex address printed on the 2016 guidance.

Source register: Subdivision and Development Regulations §§1–8, approved March 31, 2026; Design and Construction Standards Manual §§4–7, 11–12, approved March 31, 2026; 2025 OSSF Order §§6, 9, 16 and TCEQ approval dated July 17, 2025; current EDS and Environmental Health webpages. Current requirements and tract-specific exceptions must be confirmed with the responsible authority. This is not a legal or engineering opinion.