Absent a lease clause, maintenance including pumping is the landlord obligation, since it is part of keeping the property in habitable condition. Damage from tenant misuse, such as flushed wipes, is commonly charged back.
More detail
Landlord-tenant law in Ohio requires an owner to keep a rental in a fit and habitable condition and to maintain the systems that make it so, which covers the septic system as infrastructure. Routine maintenance, including scheduled pumping, sits with the owner on that basis unless the lease says otherwise. Where disputes actually happen is misuse. A tank filled with wipes, a field damaged by a vehicle parked over it, or grease poured down a kitchen drain are tenant-caused conditions, and the cost of correcting them is commonly charged back where the lease addresses it and the invoice documents the cause. That is why the pumper's notes matter: an invoice reading "tank pumped" supports nothing, while one reading "heavy non-dispersible wipe accumulation in tank and outlet baffle" supports a chargeback. The way to avoid the argument entirely is a lease clause that does three things. It states the property is on a septic system, which many tenants have never encountered. It lists specifically what must not be flushed or poured, wipes first. And it assigns routine pumping to the owner on a stated interval while assigning misuse-caused service to the tenant. Owners should also keep the pumping on their own schedule rather than waiting for a complaint. A tenant has no incentive to report slow drains early, and the difference between a $400 pump and a $10,000 field replacement is often the six months nobody mentioned it. A lease used across multiple counties should still be reviewed against local requirements.