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

Collin County septic permits cost $310-$335 for residential systems, require a minimum of 1 usable acre, and mandate 3 aerobic inspections per year under Court Order CO No. 2008-187-03-11.

Collin County is one of the fastest-growing counties in Texas, and a lot of that growth is happening in areas that rely on septic systems. If you own property in unincorporated Collin County (or in a city that hasn't been designated as its own permitting authority), the county's Development Services Department handles your septic permits. The rules here go beyond the standard TCEQ minimums, thanks to a local court order that adds stricter lot size, design, and maintenance requirements.

This guide covers permits, fees, the application process, system types, lot requirements, aerobic rules, and enforcement in Collin County. Whether you're building new, repairing an existing system, or buying a property with septic, the details are here.

Topic	Key Rule	Details
Permit authority	Collin County Development Services	(972) 548-5585
Residential permit fee	$310-$335	$310 conventional, $335 aerobic
Minimum lot size	1 usable acre (post-2008 lots)	1.5 acres with water well
Aerobic inspections	3 per year at 4-month intervals	Maintenance contract required
Permit review time	2-4 weeks	Online-only via CSS Portal
Violations	$50-$200 first offense	Up to $1,000 repeat; $5,000/day TCEQ

Who Issues Septic Permits in Collin County?

Collin County Development Services is the authorized TCEQ agent for septic permits, handling plan review, permitting, inspections, and enforcement in unincorporated areas.

The Development Services Department (part of the Collin County Engineering Department) issues all septic permits in unincorporated areas. For properties inside city limits, it depends on whether that city has been designated as an authorized agent by TCEQ. If your city isn't on the TCEQ authorized agent list, Collin County handles your permit. You can check the TCEQ's list by selecting "Collin" from the county dropdown.

Collin County administers its septic program under Court Order CO No. 2008-187-03-11, which supplements TCEQ's 30 TAC Chapter 285 and Texas Health and Safety Code Chapters 341 and 366. The county can impose stricter rules than the state minimum, and it does in several areas, particularly lot size requirements and maintenance obligations.

Contact information:

Detail	Information
Office	Collin County Development Services
Phone	(972) 548-5585
Metro	(972) 424-1460, ext. 5585
Email	DevelopmentServices@collincountytx.gov
Online portal	collincountytx.gov/Services/Engineering/Development-Services
Address	4690 Community Avenue, Suite 200, McKinney, TX 75071
Hours	Monday-Friday, 7:30 AM - 4:00 PM

All permit applications go through the Citizen Self-Service (CSS) Portal. Paper applications are no longer accepted as of November 2023.

How Much Do Septic Permits Cost in Collin County?

Residential septic permits in Collin County cost $310-$335 depending on whether the system requires maintenance. Repair permits run $100-$150, and review of an existing system costs $50.

Here's what you'll pay for the most common permit types:

Permit Type	Fee	Notes
New residential OSSF (no maintenance)	$310	Standard conventional system
New residential OSSF (with maintenance)	$335	Aerobic or alternative systems
New commercial OSSF (no maintenance)	$450	Non-residential properties
New commercial OSSF (with maintenance)	$475	Commercial aerobic systems
Repair/upgrade (under 100 ft of line)	$100	Minor repairs
Repair/upgrade (over 100 ft of line)	$150	Major repairs
Existing septic review	$50	Property sale or modification review
Reinspection fee	$75	After second failed inspection
Re-review fee	$50	Design re-review after failure

These are county permit fees only. Your total cost also includes the site evaluation by a licensed professional ($600-$1,200) and the system installation itself. If you repair or upgrade 50% or more of your system, the county requires a full new-system permit and fee instead of the repair fee.

The 10-acre exemption: If your property is 10 acres or larger with one single-family home, one septic system, and the disposal field at least 100 feet from all property lines, you may not need a county permit. But the exemption only covers the first system on the property. Even with the exemption, you still need a professional site evaluation and must meet all 30 TAC Chapter 285 technical standards. And in Collin County, all systems are subject to licensing requirements regardless of lot size.

Payment options: The CSS Portal accepts Visa, MasterCard, and Discover. You can also pay in person with cash, check, or credit card at the Development Services office.

How Do You Get a Septic Permit in Collin County?

The permit process starts with an online application through the Citizen Self-Service Portal. Review typically takes 2-4 weeks from a complete submission.

Here's the step-by-step process:

1. Check your jurisdiction. Verify that Collin County Development Services handles your permit. Check the TCEQ authorized agent list for Collin County. If your city isn't listed, the county is your permitting authority.

2. Hire a licensed site evaluator. A TCEQ-licensed professional (Professional Engineer, Licensed Professional Sanitarian, or Installer II) must evaluate your soil, conduct testing, and determine the right system type. Collin County maintains a courtesy list of qualified professionals on their website.

3. Gather documents. You'll need a site plan showing property lines, buildings, wells within 150 feet, water lines, easements, slopes, floodplain status, and the proposed system layout. For aerobic systems, you'll also need a maintenance affidavit.

4. Submit through the CSS Portal. Create an account on the Citizen Self-Service Portal, select your permit type, upload documents, and pay fees online. For new construction with a new septic system, apply for the Development Permit first. The county will then generate the associated OSSF permit. Do not apply for both separately.

5. County review. Development Services reviews your plans against Court Order CO No. 2008-187-03-11 and 30 TAC Chapter 285. Complete applications typically take 2-4 weeks. Incomplete submissions get returned and the clock restarts.

6. Authorization to construct. Once approved, only a TCEQ-licensed installer can do the work.

7. Inspections. The county inspects at required checkpoints during installation. No components can be covered until a county inspector approves them.

8. License to operate. After final inspection, you receive authorization to use the system. No dwelling may be occupied until the septic system passes final inspection and receives this license.

What Lot Size Do You Need for a Septic System in Collin County?

Collin County has tiered lot size requirements based on when the lot was subdivided. Post-2008 lots need at least 1 usable acre. Properties with water wells need 1.5 acres minimum.

Collin County's lot size rules are more detailed than what you'll find in many Texas counties. The requirements depend on when your lot was created:

Subdivision Date	Minimum Lot Size	With Water Well
Before 1983	May qualify at smaller sizes	Documentation required
1983-2008	1 acre	1.5 acres
2008 or later	1 usable acre	1.5 acres (1 acre usable)

The word "usable" matters. It means land actually available for septic components, excluding most easements, ponds, rights-of-way, and shared access driveways. A 1.2-acre lot with a large easement might not have 1 usable acre.

If your lot existed in its current size before 1983, it may qualify for a septic system even if it's smaller than current minimums. You'll need to provide documentation proving the lot's pre-1983 configuration to Development Services.

One important warning: if a lot was made smaller after the relevant threshold date (splitting a parcel, for example), the reduced lot may become ineligible for a septic system.

What Are the Aerobic System Rules in Collin County?

Aerobic systems in Collin County require a continuous maintenance contract and 3 inspections per year at 4-month intervals. The initial contract covers 2 years, and renewal documentation must be submitted 30 days before expiration.

Aerobic systems are common in Collin County because many local soils aren't well-suited for conventional systems. As Dr. Bruce J. Lesikar, Professor and Extension Agricultural Engineer at Texas A&M AgriLife Extension, notes in the agency's septic maintenance guide (L-5491), proper maintenance is critical for aerobic systems because they rely on mechanical components and biological processes that need regular monitoring. If you have an aerobic unit, here's what the county expects:

Maintenance contracts are mandatory. You must have a current contract with a licensed maintenance provider at all times. There can be no gaps in coverage. The initial contract runs 2 years from the date your system is approved. After that, you're responsible for renewing before it expires.

30-day advance renewal. Submit renewal documentation to Development Services at least 30 days before your current contract expires. This prevents any gap in coverage.

Inspection frequency: Your maintenance provider must inspect the system 3 times per year at approximately 4-month intervals. Reports go to both the county and to you.

Maintenance affidavit: When an aerobic system is installed, you must file a notarized affidavit with the Collin County Clerk's Office. This gets recorded in the deed records and notifies future buyers that the property has a maintenance-dependent system.

Chlorine requirements: If your system uses spray irrigation, you must keep chlorine in the system at all times. Use only calcium hypochlorite tablets certified for wastewater disinfection. Never use swimming pool chlorine tablets. They can release nitrogen chloride, an explosive gas that damages equipment.

No unauthorized modifications. Once your aerobic system passes inspection, you cannot alter it without a Septic Repair/Upgrade Permit. This includes moving sprinkler heads, connecting additional structures, or changing electrical connections.

After the initial 2-year contract period, you're free to switch to any licensed maintenance provider. You're not locked into the original installer.

What Happens If You Violate Septic Rules in Collin County?

Collin County investigates septic complaints within 30 days. Violations carry fines of $50-$200, with repeat offenses up to $1,000 and possible jail time of up to 6 months.

The county's enforcement follows a structured process:

What triggers enforcement:

• Operating without a permit
• Installing or modifying a system without authorization
• Letting an aerobic maintenance contract lapse
• Systems causing odors, surface sewage, or contamination
• Failing required inspections
• Making unauthorized alterations to an aerobic system

The enforcement process: When the county identifies a violation, you get a notice with a compliance deadline. You typically have 30 days to make substantial progress on fixing the problem. If you don't act, the county can file a complaint with the local justice of the peace court.

Criminal penalties: Under Texas Health and Safety Code Chapter 366, septic violations are misdemeanors. First offense fines range from $50 to $200. Repeat convictions carry fines of $200-$1,000, and possible jail time of up to 6 months. TCEQ can pursue additional civil penalties up to $5,000 per day for serious or ongoing violations.

County inspection authority: Collin County inspectors do not need permission to enter your property to spot-check your septic system or investigate complaints during normal business hours (8 AM to 5 PM, Monday through Friday).

Unpermitted work: All installation, repair, and modification work requires a permit and a licensed installer. If you repair 50% or more of a system, you need a full new-system permit.

How Much Does Septic Work Cost in Collin County?

A conventional septic system in Collin County costs $6,300-$7,500 for a 3-bedroom home, while aerobic spray systems run $7,800-$9,800 and drip systems cost $9,800-$12,000.

Compared to rural Texas counties where conventional installs may start around $4,000, Collin County homeowners pay a premium. Here's what homeowners in the McKinney, Allen, Plano, and Frisco area should budget:

Item	Cost Range
Conventional system install (3-bedroom)	$6,300-$7,500
Aerobic spray system	$7,800-$9,800
Aerobic drip system	$9,800-$12,000
Site evaluation and soil testing	$600-$1,200
County permit fee (residential)	$310-$335
Total permit + site eval	$910-$1,535
Septic pumping (1,000-gallon tank)	$235-$275
Aerobic maintenance contract (2-year)	$500-$700
Typical repair (per hour + materials)	$275-$375/hour
Drain field replacement	$5,000-$12,000

Costs in Collin County tend to run higher than many rural Texas counties due to North Texas labor rates and the prevalence of clay-heavy soils that push many properties toward aerobic systems. According to the EPA, more than one in five U.S. households rely on septic systems, and in fast-growing counties like Collin, local soil conditions make conventional systems a poor fit for many properties. Budget for aerobic system costs if you're building new.

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 Collin County?

Yes, almost always. New installations, repairs, and modifications all require a permit through the Citizen Self-Service Portal. If you repair 50% or more of your system, you'll need a full new-system permit. The 10-acre exemption applies to the first system on large lots with proper setbacks, but even exempt systems must meet all TCEQ technical standards. Routine pumping does not require a permit.

How much does a septic permit cost in Collin County?

Residential permits cost $310-$335. Standard systems without maintenance requirements cost $310, while aerobic and alternative systems cost $335. Budget another $600-$1,200 for the required site evaluation. Repair permits run $100-$150 depending on scope. Total out-of-pocket for a new install permit package is typically $910-$1,535.

Who inspects septic systems in Collin County?

Collin County Development Services handles all inspections. They inspect at key checkpoints during installation, and no components can be covered until approved. For aerobic systems, your maintenance provider conducts inspections 3 times per year at 4-month intervals and files reports with the county. The county also has authority to spot-check any system during normal business hours without prior notice.

Can I do my own septic work in Collin County?

Installation, repairs, and modifications must be done by a TCEQ-licensed installer. For conventional systems, homeowners can perform basic maintenance on their own single-family home's system. Aerobic systems require a professional maintenance contract at all times. After the initial 2-year contract, you can switch providers but cannot go without coverage. Unauthorized modifications to any system are a violation.

What lot size do I need for a septic system in Collin County?

For lots subdivided after 2008, you need at least 1 usable acre (1.5 acres if you have a water well). Lots subdivided between 1983 and 2008 need 1 acre (1.5 with a well). Lots that existed before 1983 may qualify at smaller sizes with documentation. "Usable" means land available for septic components after excluding easements, ponds, and rights-of-way.

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Last updated: February 6, 2026 Reviewed by: Texas Septic Guide Editorial Team, content verified against TCEQ regulations, Collin County Court Order CO No. 2008-187-03-11, and 30 TAC Chapter 285

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Sources: Collin County Development Services Department; Collin County Court Order CO No. 2008-187-03-11; Texas Commission on Environmental Quality (TCEQ), 30 TAC Chapter 285; Texas Health and Safety Code Chapter 366; Collin County FY 2026 Adopted Fee Schedule; U.S. Environmental Protection Agency, Septic Systems Overview; Texas A&M AgriLife Extension Service, L-5491.

Serving Collin County communities: McKinney | Allen | Plano | Frisco