Septic System Repair & Installation in Conroe, TX — Permits, Soil, and Real Costs

Septic work in Montgomery County is not a handshake job. New systems and major repairs run through Montgomery County Environmental Health Services, require a soil analysis by a Registered Site Evaluator and a design sealed by a Registered Sanitarian or Professional Engineer, and get inspected before they’re buried. That’s good news for homeowners — it keeps the cut-rate operators honest — but it means you should know the process before the first bid arrives.

Failed field, alarm that won’t quit, or building on raw land? Use the quote form — request a quote online — and we’ll match you with a licensed local installer or repair pro.

Do I need a permit to repair or replace a septic system in Montgomery County?

For anything beyond minor maintenance, yes:

• New systems: full permit. County fee is $295 ($285 + $10 TCEQ assessment), plus the site evaluation and design you pay professionals for. The county requires three sets of the design, floor plans showing bedrooms and square footage, and a floodplain determination. No septic permits are issued in the regulatory floodway.
• Tank replacement or drain field repair/replacement: permit required under TCEQ rules.
• Emergency repairs that don’t require removing the tank (a broken pipe, a failed pump swapped like-for-like): exempt from permitting, but the work must be reported to the county within 72 hours.
• Final step for permitted work: a county Notice of Approval inspection before the system is backfilled. Inspections must be requested by 3:00 p.m. two business days ahead. A contractor who wants to cover the work before the county sees it is telling you something.

Permit office: 501 N. Thompson, Suite 100, Conroe; septic questions (936) 539-7839.

Why are aerobic septic systems so common around Conroe?

Because of what’s under the grass. Much of Montgomery County has sandy or loamy topsoil over slowly draining clayey subsoil. A conventional system needs soil that can absorb effluent; where the required soil analysis finds restrictive clay or seasonal wetness, a conventional drain field won’t be approved. The standard answer here is an aerobic treatment unit (ATU) with spray (surface application) or drip distribution — it treats wastewater to a higher standard, then distributes it where the soil can’t absorb a conventional load.

Aerobic systems come with real obligations:

• Ongoing professional inspection. TCEQ rules require aerobic/surface-application systems to be checked by a licensed maintenance provider on a recurring schedule — typically every four months. Maintenance contracts in Texas commonly run $300–$600 per year (2026 figures).
• Spray setbacks: the edge of the spray area must be at least 100 feet from a private well and 150 feet from a public well, among other separation distances.
• Electricity and parts: aerators, pumps, and floats wear out. Budget for it.

After the initial two years, Texas rules allow homeowners to maintain some aerobic systems themselves where the local permitting authority allows it — but counties can be stricter, training may be required, and most owners keep a contract anyway. Ask the county before assuming.

What does a septic system cost in the Conroe area?

Honest ranges, labeled: these are Texas and national 2026 figures, not local quotes. Your soil evaluation drives everything.

Lot size matters too: county guidance calls for at least 0.75 acre for a septic system on public water, and at least 1.5 acres if the lot has both a septic system and a private well. Lots recorded before December 1, 1986 can get special consideration if separation distances still work — relevant for older subdivisions and lake lots.

Repair or replace? How to read a failing system

• One-time backup after a party weekend: probably overload, not failure. Pump, conserve, watch.
• Soggy drain field that never dries, sewage odor outside: the field itself is likely biologically clogged or undersized. Partial or full field replacement territory — permit required.
• System age 25+ years, repeated problems: TCEQ notes systems older than about 15 years are entering the zone where replacement gets likelier. Stop pouring repair money into a field at end-of-life; price replacement and compare.
• Aerobic alarm + dead aerator: usually a component repair, not a system failure. These systems are designed to be fixed part-by-part.

When DIY is fine

• Diverting surface water away from the drain field — extending downspouts, regrading a low spot — is free-to-cheap and genuinely extends field life.
• Replacing a like-for-like aerobic sprinkler head or a float switch is within reach for a handy owner if the local authority permits homeowner maintenance on your system class and you kill power first. When in doubt, your maintenance contract covers it.
• Keeping records: photograph lids, sketch the layout, file the county paperwork. Future-you (and the next buyer) will be grateful.
• What’s never DIY: tank setting, drain field construction, spray field layout, anything needing the sealed design. Texas requires licensed installers for OSSF construction, and unpermitted work surfaces at resale — Montgomery County keeps the records, and buyers’ inspectors ask for them.

And before any digging anywhere on the property: call 811 (Texas811) for utility locates. It’s free and it’s the law.

Frequently asked questions

How much does a new aerobic septic system cost in Texas?

National and Texas 2026 figures run roughly $10,000–$20,000 installed, including tank, treatment unit, and spray distribution — plus the site evaluation, sealed design, and the $295 Montgomery County permit. Soil conditions, lot layout, and house size (design is based on bedrooms) move the number. Always get multiple local bids.

Can I install my own septic system on my land in Montgomery County?

Texas law lets an owner install a conventional system on their own single-family property in some circumstances, but the permit, site evaluation, sealed design, and county inspection still apply, and aerobic systems require licensed installation and maintenance. In practice, almost everyone here uses a licensed installer — the soil usually demands an aerobic design anyway.

How long does a septic drain field last?

A well-built, well-maintained conventional field commonly lasts 20–30 years; neglect can kill one in under 10. The biggest life-extenders are boring: pump the tank on schedule so solids never reach the field, keep vehicles off it, and keep roof and surface water away from it.

What is a “site evaluation” and why do I have to pay for one?

It’s a soil and site analysis performed by a state-Registered Site Evaluator — required by Montgomery County before any system is designed. It determines soil texture, restrictive layers, and seasonal water table, which dictate what system types are even allowed on your lot. It protects you: a system matched to bad soil data fails early.

My septic system was never permitted. What now?

Call Montgomery County Environmental Health Services and ask about bringing it into compliance — many older systems predate enforcement, and the county deals with this constantly. Don’t wait for a sale to force the issue: unpermitted systems complicate disclosure (Texas sellers must disclose known septic details) and can blow up a closing.

Does heavy clay soil mean I can’t have septic at all?

Almost never. It usually means a conventional drain field is off the table and the design moves to an aerobic unit with spray or drip distribution, which is exactly why those systems dominate new installs around Conroe. The site evaluation tells you definitively — that’s its job.

Get bids from licensed local installers: request a quote online

JM Marketing Co is a referral service connecting you with independent, TCEQ-licensed septic installers and maintenance providers. We don’t perform the work; pricing shown is national/Texas 2026 data for planning, not a quote. How this works →