Selling a San Antonio Home on a Septic System: The OSSF Disclosure, Inspection, and What Lenders Actually Require

If your home isn't connected to SAWS sewer, you're selling with an On-Site Sewage Facility (OSSF) — a septic system regulated by the TCEQ under 30 TAC Chapter 285 and permitted locally by Bexar County Public Works (or Kendall, Comal, Guadalupe County if you're in Boerne, Bulverde, Cibolo, or Schertz outskirts). That single fact changes your disclosure, your buyer pool, your inspection timeline, and often your closing date. Sellers who treat the septic like a footnote lose deals in the option period. Sellers who front-load it close on time.

This is the practical checklist: what to pull before you list, what Section 4 of the Seller's Disclosure actually asks, what FHA/VA/USDA lenders demand, and where the aerobic maintenance contract trips people up.

Where OSSFs actually are in the San Antonio market

Inside Loop 1604, most homes are on SAWS sewer. Outside 1604, it depends entirely on the subdivision and the year built:

• Helotes, Grey Forest, Scenic Oaks (78023, 78255) — heavy septic, especially on 1+ acre lots north of Bandera Road.
• Bulverde, Spring Branch (78163, 78070) — almost entirely OSSF; Comal County permits.
• Far east Bexar toward St. Hedwig and China Grove (78152, 78263) — mostly septic on acreage lots.
• Boerne ETJ and Kendall County (78006, 78015 outside city limits) — OSSF plus often well water.
• Somerset, Von Ormy, Elmendorf — septic common on rural south-side parcels.
• New master-planned areas near 281 North and 1604 — some are on private wastewater utilities (not SAWS, not septic), which is a third category with its own disclosure rules.

Don't assume. Pull your property record at Bexar County Public Works OSSF search (or the equivalent county office) before you sign a listing agreement. If there's no permit on file for a system that clearly exists, that's a problem you want to solve before a buyer's inspector finds it.

Section 4 of the Seller's Disclosure: what the OP-H actually asks

The TREC OP-H Seller's Disclosure Notice, Section 4, requires you to identify whether the property is served by a public sewer system, an OSSF, or neither. If it's an OSSF, you must state the type — conventional (gravity, anaerobic), aerobic (with a spray field and pump), or other — and disclose known defects.

Under Texas Property Code § 5.008, this disclosure has to be delivered on or before the effective date of the contract. Delivering it late gives the buyer a 7-day termination right after receipt. On a septic home, the disclosure needs to include:

• System type and approximate location (drain field, tank, spray heads).
• Age, if known, and last service date.
• Any known malfunctions — surfacing effluent, alarm activations, slow drains, backups.
• Whether the system has a current maintenance contract (mandatory for aerobic).
• Whether the system was permitted, and by whom.

If you inherited the house or bought it years ago and don't have records, say so — "unknown" is a legitimate answer when it's true. Guessing is not. A buyer's inspector who finds a system you claimed was "working fine" three months after a failed pump will produce a demand letter, and § 5.008 makes that letter stick.

Aerobic systems and the maintenance contract nobody tracks

Aerobic systems — the ones with a small treatment plant, an air pump, chlorine tablets, and spray heads — are the most common newer install in Bexar and Comal counties. Under 30 TAC § 285.91, aerobic OSSFs require a continuous maintenance contract with a licensed maintenance provider. Two inspections per year minimum, plus effluent quality reporting to the permitting authority.

What trips sellers up: the contract runs with the owner, not the property. When you sell, the buyer needs a new contract in their name, and the old one terminates. Before closing:

• Confirm your current contract is paid up and reports are current with the county.
• Ask your maintenance provider for a transfer letter or a written statement that the system is in compliance.
• Get the last two inspection reports and put them in your listing file.

If reports are missing or the system is out of compliance, the county can require corrections before permit transfer. That can add two to four weeks and is not something you want a buyer's lender to discover during underwriting.

What FHA, VA, and USDA lenders require

Cash buyers can waive whatever they want. Financed buyers can't. If your buyer is using an FHA, VA, or USDA loan — very common in the sub-$400K range in far Bexar and Kendall County — the appraiser and lender will apply specific OSSF rules:

• FHA (HUD Handbook 4000.1): septic must be functional; if the appraiser sees evidence of failure (odor, wet spots, surfacing effluent), a septic inspection is required. Distance requirements between the drain field and the well matter here — typically 50 feet minimum, more for some system types.
• VA: requires a septic inspection when the appraiser flags concerns or when local practice requires it. In Bexar and surrounding counties, most VA appraisers do flag it.
• USDA (Section 502): septic inspection is essentially always required, and the system has to have remaining useful life adequate for the loan term.

A typical OSSF inspection for a real estate transaction runs $300–$500 and must be done by a licensed OSSF installer or maintenance provider — a general home inspector's septic notes are not enough for a lender.

The well-and-septic combo

If you're also on a private well, add a water quality test (bacteriological, nitrates, sometimes lead) to the checklist. VA and USDA both require it. The lab turnaround is 3–5 business days; build that into your timeline.

Pre-listing septic inspection: when it's worth it

For homes over 15 years old, or any home with an aerobic system where you can't produce recent maintenance reports, pay for a pre-listing OSSF inspection. Reasons:

1. You control the finding. If there's a bad pump or a saturated drain field, you can repair before a buyer's inspector uses it as leverage on a TREC 39-9 amendment.
2. You can price the home honestly. A failing conventional system on a lot with poor percolation may require conversion to aerobic — a $8,000–$15,000 job in this market. That number belongs in your pricing, not in a repair negotiation two weeks before closing.
3. You shorten the option period conversation. A buyer who sees a clean inspection dated 30 days ago has less to fight about.

What most people get wrong

• Assuming "it's been fine for 20 years" is disclosure. It isn't. § 5.008 asks about known conditions and defects. Long-term function is not the same as absence of defects, and the OP-H doesn't have a box for optimism.
• Forgetting the aerobic contract transfers by contract, not automatically. The buyer's lender will ask for evidence of an active maintenance agreement in the buyer's name at closing. Line this up two weeks out, not the morning of.
• Treating a home inspector's septic comments as adequate. They aren't for FHA/VA/USDA. You need a licensed OSSF professional's report.
• Missing well setbacks. If your well is closer than the required setback from the drain field, spray heads, or livestock, an appraiser can call it out. Measure before you list.
• Not pulling the permit history. If the county has no permit for the system, or the permit shows a different system than what's actually installed (common on homes where an aerobic was retrofitted informally), you have a title-and-disclosure problem that surfaces at the worst possible moment.
• Pricing like a SAWS-connected comp. A septic home in 78023 does not comp cleanly against a SAWS-sewered home in 78250. Your agent should be pulling septic-to-septic comps, not raw ZIP-code averages.

The closing-day handoff

At closing, hand the buyer a folder containing: the permit and any as-built diagram, the last two maintenance reports, the new maintenance contract (or the transfer paperwork), the inspection you paid for, and the well water test if applicable. Title companies don't require this. Buyers remember it, and it's the cheapest way to prevent a post-closing complaint about something you already disclosed.

If you're getting ready to list a septic home and want to see how comparable homes in Helotes, Bulverde, or far east Bexar are priced right now, browse active listings on HomeFinder or start a free FSBO listing at /list-your-home. If you'd rather have a local agent who has closed septic-and-well transactions before, /agents will let you filter for rural and acreage experience.