Montgomery County Septic Regulations: What Homeowners Need to Know in 2026

Montgomery County issues septic permits through its Public Health District in Conroe, requires 1-1.5 acre minimum lots, and mandates aerobic systems in floodplains.

Montgomery County is one of the fastest-growing counties in Texas, with a population of nearly 750,000 as of 2024 (U.S. Census Bureau) and annual growth around 4.8%. Subdivisions are spreading into areas that aren't connected to municipal sewer, which means thousands of homes rely on septic systems. The county runs its own permitting program through the Montgomery County Public Health District, and the rules are tighter than the state minimum in several areas, especially around lot size, floodplain building, and Lake Conroe.

This guide covers who handles permits, the application process, lot size rules, system types, aerobic maintenance, Lake Conroe watershed requirements, enforcement, and costs. Whether you're building new, replacing a failing system, or just trying to stay compliant, here's what Montgomery County requires.

Regulation Area	Montgomery County Rule	Key Detail
Permitting authority	MCPHD Environmental Health	Office in Conroe, ePlans online system
Minimum lot (public water)	1 acre	Lots platted after Jan 1, 1988
Minimum lot (private well)	1.5 acres	Stricter than many TX counties
Floodplain systems	Aerobic required	Conventional prohibited
Lake Conroe properties	Dual permits needed	SJRA + county, extra $300 fee
Aerobic maintenance	Reports every 4 months	Contract required for system life
Violation fines	$50-$200/day	Each day counts separately

Who Handles Septic Permits in Montgomery County?

The Montgomery County Public Health District (MCPHD) Environmental Health Services division issues all septic permits in unincorporated Montgomery County.

The office is located at 501 North Thompson, Suite 101, in Conroe. An east county satellite office also handles environmental health services for residents closer to that side of the county.

Under 30 TAC Chapter 285, TCEQ has authorized Montgomery County to administer its own OSSF (on-site sewage facility) permitting program. That means you deal with the county for permits, inspections, and enforcement rather than going through the state directly. The county can and does set rules stricter than TCEQ's baseline.

One exception: if your property is within 2,075 feet of Lake Conroe, the San Jacinto River Authority (SJRA) is your additional permitting authority. More on that below.

Contact information:

Detail	Information
Office	Montgomery County Public Health District, Environmental Health Services
Address	501 North Thompson, Suite 101, Conroe, TX 77301
Phone (Main)	(936) 539-7839
Phone (Alt)	(281) 364-4200 ext. 7839
East County Office	(281) 689-3133 ext. 7839
Website	mcphd-tx.org

The department recently launched an ePlans electronic permitting system, so you can submit applications, check permit status, schedule inspections, and pull historical records online rather than making a trip to the Conroe office.

What Are the Permit Types and Fees in Montgomery County?

Montgomery County permit fees range from $150 for repairs to $500+ for new installations. Call (936) 539-7839 for the current schedule.

Here's what to expect for common permit types based on comparable Texas county fee structures:

Permit Type	Estimated Fee	Notes
New septic system permit	$300-$500	Standard residential installation
Repair permit	$150-$300	Replacing or repairing a failing system
Soil evaluation / perc test	$400-$850+	Per lot, varies by system type
SJRA permit (Lake Conroe)	$300	Additional fee for properties within 2,075 ft of lake
Permit extension	$150-$200	One-time 6-month extension available
State septic fee	$10	Non-refundable, added to all permits

These are county permit fees only. You'll also pay a licensed site evaluator or professional engineer $600-$1,200 for the required soil analysis and site evaluation. Licensed installers often handle the permit application as part of their service.

The 10-acre exemption: Under TCEQ rules (30 TAC Chapter 285), properties of 10 acres or more with a single home and a single septic system may not need a county permit, as long as the disposal area is at least 100 feet from all property lines. The system still must meet every technical standard. This exemption covers only the first system on the property.

How Does the Montgomery County Septic Permit Process Work?

The permit process runs through the county's ePlans system, with review typically taking 2-4 weeks from complete submission to construction authorization.

Here's the step-by-step process:

1. Check your jurisdiction. Make sure your property is in unincorporated Montgomery County. If you're inside Conroe, The Woodlands, or another incorporated area, your permitting may go through a different authority. Properties near Lake Conroe also need SJRA permitting.

2. Hire a site evaluator. You'll need a registered sanitarian or licensed professional engineer to evaluate your soil, determine system placement, and assess site conditions. Montgomery County no longer uses the old percolation ("perc") test method. Modern soil analysis evaluates texture, permeability, horizon depth, and seasonal water table levels.

3. Gather documents. Your application package needs: site evaluation report, property survey showing buildings, wells within 150 feet, property lines, roads, easements, floodplain status, and the proposed system layout. Aerobic systems require a signed Affidavit to the Public filed with the Montgomery County Clerk.

4. Submit application. Log into the county's ePlans system, upload all documents, and pay fees. The county also accepts in-person submissions at the Conroe office.

5. County review. Environmental Health Services reviews your plans against county rules and 30 TAC Chapter 285. Standard review runs 2-4 weeks for complete applications. Incomplete submissions get returned.

6. Authorization to construct. Once approved, you receive a construction permit. Only a TCEQ-licensed installer can do the work.

7. Inspections. The county inspects at key points during installation. No components can be covered or buried until a county inspector approves them.

8. Certificate of completion. After the system passes final inspection, you're cleared to operate. Failed inspections require corrections and reinspection.

Permits are valid for 12 months from issuance, with one possible 6-month extension. After that, you'll need to reapply and pay again.

Repair permits are expedited. If you're replacing a failing system on an existing home, Montgomery County fast-tracks the review and issues permits as quickly as possible, recognizing the public health urgency.

What Are the Lot Size Requirements in Montgomery County?

Montgomery County requires 1 acre minimum with public water, or 1.5 acres with a private well. These rules apply to lots platted after January 1, 1988.

This is stricter than many Texas counties and reflects Montgomery County's focus on protecting groundwater in a fast-growing area.

Lot size rules by water source:

Water Source	Minimum Lot Size	Max Dwellings Per Acre
Public water + septic	1 acre	1 dwelling per acre
Private well + septic	1.5 acres	1 dwelling per 1.5 acres

Grandfathering exception: Properties recorded before January 1, 1988 can install septic systems on smaller lots, as long as proper separation distances between the system, wells, property lines, and structures can be met and soil conditions are suitable.

Dwelling density example: If you own 3 acres with public water and septic, you could have up to 3 single-family homes. With well water and septic on the same 3 acres, the maximum drops to 2 homes.

Do You Need a Conventional or Aerobic System in Montgomery County?

Your soil determines your system type in Montgomery County. Conventional systems work in sandy, well-draining soil, while aerobic systems are required in floodplains and heavy clay areas.

Montgomery County doesn't mandate aerobic systems across the board. But the county's mix of sandy soils in some areas and heavy clay in others means many properties end up needing an aerobic system based on the soil analysis.

When you'll need an aerobic system:

• Properties in the floodplain (conventional systems are prohibited)
• Heavy clay soils that don't drain fast enough for conventional treatment
• Sites with a seasonal high water table
• Properties where soil analysis shows insufficient percolation rates

When a conventional system works:

• Sandy soils with no seasonal water table issues
• No restrictive soil horizons in the disposal area
• Adequate separation between the drain field and groundwater

For floodplain properties, all planning materials must be pre-approved through Commissioners Court before installation can begin. That adds an extra step and some time to the process.

What Are the Lake Conroe Watershed Septic Rules?

Properties within 2,075 feet of Lake Conroe fall under San Jacinto River Authority (SJRA) jurisdiction and need a separate SJRA permit on top of the county permit.

The SJRA adopted specific rules for on-site sewage facilities near Lake Conroe in December 2015 to protect the reservoir's water quality. If your property is close to the lake, you're dealing with two permitting authorities.

What SJRA requires:

• OSSF design approved by a professional engineer or registered sanitarian
• Soil and site analysis stamped by a registered site evaluator
• Initial two-year maintenance contract signed by both installer and homeowner
• Affidavit to the Public filed at the Montgomery County Clerk's office
• SJRA permit fee of $300

SJRA inspection: After your system is built, the installer must contact SJRA for a separate inspection. The installer must be on-site during the inspection. If the system passes, SJRA issues an approval tag and your operating license.

Use the SJRA OSSF Data Viewer map at sjra.net to check whether your property falls within their 2,075-foot jurisdiction.

What Does Montgomery County Require for Aerobic Systems?

Aerobic septic systems in Montgomery County require a maintenance contract with a licensed provider and reports filed to the county at least every 4 months.

If you have an aerobic treatment unit, here's what the county expects:

Initial maintenance contract: Your installer provides the first two years of maintenance as part of the installation. After that two-year period, you're responsible for hiring a licensed maintenance provider and keeping the contract active for the life of the system.

The Affidavit to the Public: By signing this document (filed with the Montgomery County Clerk), you acknowledge that you must employ a wastewater operator, that the operator will provide testing and reporting per TCEQ schedules, and that you'll operate the system in compliance with state discharge standards. Breaking these commitments can result in citations.

Reporting schedule: Your maintenance provider must submit reports to Montgomery County and to you at least every 4 months. If your system has electronic monitoring that alerts the provider to failures and tracks disinfection levels, reporting can drop to every 6 months.

What the maintenance provider checks:

• Aerator and blower operation
• Alarm system function
• Disinfection unit (chlorine or UV)
• Wastewater quality
• Spray heads or drip emitters
• General system condition

Budget $200-$400 per year for a standard aerobic maintenance contract in the Montgomery County area. As Texas A&M AgriLife Extension water resources specialist Diane Boellstorff notes in the agency's septic maintenance guide (SC-015), proper maintenance of on-site systems is critical to protecting both well water and local groundwater quality.

What Happens If You Violate Septic Rules in Montgomery County?

Montgomery County investigates septic complaints and issues citations for violations. Fines under Texas law range from $50-$200 per day, and each day of violation counts as a separate offense.

What triggers enforcement:

• Surface discharge of sewage (system failure)
• Installing or repairing a system without a permit
• Failing to maintain an aerobic system maintenance contract
• Systems causing a nuisance (odors, visible sewage)
• Improper abandonment of old systems

The enforcement process: When the county identifies a violation, you receive notice with a compliance deadline. First-time malfunctions typically get a 30-day window to make substantial progress on repairs. If you've been notified of the same problem twice in 12 months, that deadline drops to 10 days. Immediate health hazards (active sewage discharge) require action as soon as practicable.

Penalties under Texas law:

• First offense: Misdemeanor, fine of $50-$200 per day of violation
• Repeat offense (within one year): Fine up to $1,000, possible jail up to 30 days
• Administrative penalty for homeowner self-maintenance violations: Up to $100
• Maintenance company violations: $200 first offense, $500 for subsequent violations

Per Texas Health and Safety Code Chapter 366, TCEQ can also pursue civil penalties up to $5,000 per day for serious or ongoing violations.

How Much Does Septic Work Cost in Montgomery County?

A conventional septic system in Montgomery County runs $5,500-$8,500 installed for a 3-bedroom home, while aerobic systems cost $10,000-$20,000. Floodplain and Lake Conroe properties typically hit the higher end.

Here's what homeowners in the Conroe and Woodlands area should budget:

Item	Cost Range
Conventional system install (3-bedroom)	$5,500-$8,500
Aerobic system install	$10,000-$20,000
Site evaluation and soil testing	$600-$1,200
County permit fee (new install)	$300-$500
SJRA permit (Lake Conroe properties)	$300
Total permit + site eval	$900-$2,000
Septic pumping (1,000-gallon tank)	$250-$375
Aerobic maintenance contract (annual)	$200-$400
Typical repair	$250-$350/hour + materials
Drain field replacement	$5,000-$12,000

Montgomery County costs are generally in line with the greater Houston metro area. Properties in the floodplain or near Lake Conroe can expect higher costs due to the aerobic system requirement and additional SJRA permitting. With the county's population reaching 749,613 in 2024 (a 4.8% annual growth rate per U.S. Census estimates), demand for qualified installers in The Woodlands and Conroe corridor has pushed scheduling out and can affect pricing.

For a full breakdown of Texas septic costs, see our septic pumping cost guide.

Frequently Asked Questions

Do I need a permit for septic work in Montgomery County?

Yes, all new installations, repairs, and modifications require a county permit through Environmental Health Services. The only exception is the 10-acre exemption for single-family homes on large lots with proper setbacks. Routine pumping does not require a permit. Properties near Lake Conroe also need a separate SJRA permit.

How much does a septic permit cost in Montgomery County?

New installation permits run $300-$500, with repair permits at $150-$300. Call the Environmental Health office at (936) 539-7839 for the current fee schedule. Budget another $600-$1,200 for the required site evaluation, plus $300 for SJRA if you're near Lake Conroe.

What's the minimum lot size for a septic system in Montgomery County?

1 acre with public water, or 1.5 acres with a private well. These minimums apply to lots created after January 1, 1988. Older properties may qualify for smaller lot installations if proper separation distances can be maintained.

Do I need an aerobic system in Montgomery County?

Not necessarily. The system type depends on your soil and site conditions. Properties with sandy, well-draining soil can install conventional systems. Properties in the floodplain must use aerobic systems (conventional is prohibited). Heavy clay soils or high water tables also typically require aerobic treatment.

What are the Lake Conroe septic rules?

Properties within 2,075 feet of Lake Conroe need a separate SJRA permit costing $300, on top of the county permit. The SJRA requires a professional engineer or sanitarian design, soil analysis, two-year maintenance contract, and a filed Affidavit to the Public. SJRA conducts its own inspection before issuing an operating license.

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Last updated: February 7, 2026 Reviewed by: Texas Septic Guide Editorial Team, content verified against TCEQ regulations, Montgomery County OSSF requirements, SJRA Lake Conroe rules, and 30 TAC Chapter 285

Need septic help in Montgomery County? Get free quotes from vetted local providers

Sources: Montgomery County Public Health District, Environmental Health Services Division; San Jacinto River Authority (SJRA), Lake Conroe OSSF Rules; Texas Commission on Environmental Quality (TCEQ), 30 TAC Chapter 285; Texas Health and Safety Code Chapters 341 and 366.

Serving Montgomery County communities: The Woodlands | Conroe