Short answer: a private septic system and a private well are the property owner's to maintain and repair, full stop, no utility or agency backstops either one. A SHARED septic or well follows the recorded easement or users' agreement, which usually splits common infrastructure and leaves each owner covering their own tank, pump, or service line. And if a public sewer main reaches your property, a city can require you to abandon your septic system and connect at your own expense.
Septic repair and replacement: the owner's job
EPA is explicit that septic upkeep, including repairs and full replacement, sits with whoever owns the property:
"The owner of the system (i.e., the homeowner, property owner, homeowner's association, or other responsible management entity) is responsible for the overall operation, maintenance, and upkeep of the system, including repairs or replacement."
EPA
That duty doesn't disappear if you cancel a sale. Massachusetts' DEP guide: "If a system fails inspection and the owner decides not to sell as a result, the owner still has an obligation to repair the system."
Routine septic pumping and maintenance
Pumping and inspection costs are also the owner's, not the tenant's:
"Routine maintenance is the responsibility of the home or property owner. If you rent a home, you have responsibility for the proper use and operation of the system."
EPA
EPA's general schedule is a septic tank inspected every 1 to 3 years and pumped every 3 to 5 years, though the exact interval depends on tank size and household size.
Shared septic systems: follow the recorded agreement
When a drainfield or distribution system serves more than one property, a recorded users' agreement approved by the local health district governs the split. A real Washington example, drawn from a county-recorded agreement, shows the pattern:
"Cost of repairing or maintaining common distribution pipelines and the common shared drainfield shall be born equally by all properties. Each party in this agreement shall be responsible for the maintenance, repair, and replacement of their own septic tank, pump chamber, transport piping..."
Chelan-Douglas Health District (recorded agreement)
Private well repair: no utility backstop
Private wells fall entirely outside federal drinking-water regulation, which is why there's no agency to call when one fails:
"Many Americans receive their drinking water from a private well. These wells are not regulated by EPA or required to follow EPA's standards."
EPA
The same holds for drilling a new well: EPA directs owners to "hire a certified well driller for any new well construction, modification, or abandonment and closure." No program pays that bill as a matter of right, and annual testing for contamination (coliform, nitrates, pH) is the owner's cost too.
Shared well agreements
Shared wells work the same way as shared septic: a recorded agreement, not a handshake, decides the split. The Water Systems Council, an industry nonprofit, not a government body, whose model is built on a HUD/USDA Rural Development template, publishes a widely used sample:
"Pay or cause to be paid promptly, a proportionate share of all expenses for the operation and maintenance of the well and water distribution system that may become necessary." (Water Systems Council, sample shared well agreement)
The same sample agreement then divides each expense by two, so the supplying and the supplied party each pay one half of a necessary repair or replacement.
Under that same model, each owner agrees to "promptly repair, maintain and replace all water pipes or mains" that serve their own dwelling.
Well and septic inspection at sale
Where a state mandates a point-of-sale inspection, the owner arranges it by default, though the paperwork can reassign it. Massachusetts' Title 5 rule (our record) requires inspection "within 2 years before a sale": "The property owner or operator is responsible for arranging the inspection. The buyer and seller may change the responsibility for arranging the inspection prior to title transfer, provided that this change is put in writing."
Failed septic and county enforcement
Septic systems aren't federally regulated, "Individual onsite systems are regulated by states, tribes and local governments, not the federal government," per EPA, but local health departments issue permits and can order a failing system fixed. The county enforces; the owner still pays for the fix.
Mandatory sewer connection
A working septic system doesn't protect you once a public sewer reaches your street. Portland's municipal code is a representative example of a pattern used by cities and counties nationwide:
"An existing structure served by a lawfully-permitted onsite wastewater treatment system may be required to connect at the discretion of the City, in consultation with the sanitarian, when a public sewer system becomes available."
City of Portland, Oregon
Refusing isn't free, the code treats a skipped connection as a nuisance subject to abatement and cost recovery against the owner. Portland offers loans and deferrals, but that's assistance with the cost, not the city covering it.
Rules on shared systems, sale-time inspections, and connection mandates vary by state and county, confirm the local version before you budget. Start at the city lookup or browse by issue for the specific rule where you live. This is general information, not legal advice; rules vary by state/county.