Neither Ohio nor Kentucky law assigns it; it is negotiated in the purchase contract. Sellers usually repair before closing, credit the buyer, or lower the price. What the law does require is honest disclosure of known sewer problems on the state disclosure form.
More detail
The deal decides who pays, but the disclosure rules shape the negotiation. In Ohio, Revised Code 5302.30 requires the residential property disclosure form, and its sewer section asks the seller to identify the system type, give the date of the last inspection and who performed it, and describe any previous or current leaks, backups, or other material problems along with repairs made in the past five years. A buyer who receives the form after signing a contract may rescind within three business days. In Kentucky, KRS 324.360 requires disclosure of the source and condition of sewage service, and the Real Estate Commission's Form 402 asks for the servicer, the last septic inspection date, the date the tank was last cleaned, and any known problems. When a buyer's inspection turns up a problem, the usual options are a repair before closing, a credit at closing, a lower price, or a holdback in escrow that your agent and the lender agree to. Timing favors fixing small items fast: a baffle, lid, or filter is a repair with no permit, but replacing a drain field or tank needs a health district permit and a registered installer, and starting before the permit is issued draws a 25 percent penalty in Hamilton, Butler, Warren, and Clermont counties. That permit step is why a seller who learns about a failed field in week three of a contract has fewer choices than one who learned before listing. Public repair money rarely helps a seller: the Ohio EPA-funded programs run through local health districts are income-based, and Clermont County's rehabilitation program, for example, is limited to owner-occupied single-family homes. The cheapest protection is a pre-listing evaluation with the tank pumped, so small findings get fixed on your schedule and the disclosure form is accurate. Book it through our septic inspection page, and read what else is required in our selling with septic FAQ.