Answer first: sort the septic before you list, not after the option period starts

The single biggest thing you can do as a seller in Ellis County is get the septic system inspected and serviced before you put a sign in the yard. Buyers here are used to asking about septic, especially on aerobic systems, and a stack of clean records answers most of the tough questions before they turn into repair requests.

What do buyers and lenders actually ask about?

In Waxahachie and the surrounding towns, three questions come up almost every time:

Is the system aerobic or conventional, and how old is it? Most homes on unincorporated acreage around Waxahachie, Midlothian, Red Oak, and Ovilla are aerobic because of the Blackland Prairie clay. Age matters because it drives expected maintenance cost.
Is there a current maintenance contract on file? TCEQ requires aerobic systems to be under a continuous contract with a licensed maintenance provider. Buyers, and often lenders, want to see it.
When was the tank last pumped, and can I see the report? No records is not a fatal flaw, but it makes buyers assume the worst. A recent pump-out receipt with a clean sludge measurement settles it.

Should you do a pre-listing septic inspection?

Yes on almost every septic sale in Ellis County. A pre-listing septic inspection lets you know what the buyer's inspector is going to find and gives you a chance to fix small issues on your own schedule rather than during an option period. Common items that come up: worn spray heads, a tired aerator, a chlorinator that ran dry, a full effluent filter, or a tank that is simply due for pumping. Nearly all of those are inexpensive to fix if you catch them before the buyer's inspector does.

How does an aerobic maintenance contract transfer to a buyer?

The maintenance contract is between the homeowner and a licensed maintenance provider, so it does not automatically follow the property. What sellers usually do is provide the buyer with the current provider's name, the contract expiration date, and copies of the most recent service reports. The buyer then either continues with the same provider or signs a new contract on closing. Either way, the county OSSF office wants a continuous contract on file with no gap.

What do you have to disclose as a Texas seller?

The Texas Seller's Disclosure Notice specifically asks about the type of sewage system and any known defects. Answer it honestly and attach any inspection or maintenance records you have. Trying to hide a known problem is far more expensive later than fixing it up front.

Which septic issues actually kill deals in Ellis County?

An expired or missing aerobic maintenance contract. This is the most common surprise in the option period.
Standing water or sewage smell over the drain or spray field. This tells the buyer the field is failing, and repair or replacement is a real number that has to get negotiated.
An unpermitted addition that added bedrooms. Bedroom count drives sizing. If a home was originally permitted for 3 bedrooms and now has 5, the system may be undersized and the county may want it addressed.
No permit on file for the current system. This happens on older homes and takes extra work to sort out with the county before closing.

What should the seller have ready at listing?

Recent pump-out receipt (ideally within the last 12 months).
Current aerobic maintenance contract and the last three service reports.
Original septic permit or as-built if you can find it.
Pre-listing inspection report from a licensed septic pro.

Selling a House with a Septic System in Ellis County: What to Expect