Septic or city sewer: settling it for one house

The question sounds like it should have an obvious answer. It often doesn’t, especially on a place that changed hands a few times and came with a seller’s disclosure that says “unknown” next to sewage. The sections below work through one house, cheapest check first.

How can you tell if a house is on septic or city sewer?

Three reads settle most houses: the utility bill, the yard, and the records. If the bill carries no sewer charge and the yard has a buried tank lid downhill of the house, it is septic, and the tank needs septic tank pumping on a schedule whether anyone has done it lately or not.

The fast version, in the order that costs the least effort:

1. Read the last utility bill. A city sewer charge means the house is connected. No city bill at all, or water only, points the other way.
2. Walk the yard on the side where the main drain leaves the house. A tank lid or riser there means septic. A small capped pipe alone proves nothing, since sewer houses have those too.
3. When the first two disagree, the permit and connection records decide it (more on that below).

If it turns out to be septic and nobody can say when it was last emptied, that first visit is the one that matters most. On a 1,000-gallon tank a routine pump-out runs $275 - $395, and the page on what a first pump-out costs here shows the larger sizes. After that, the schedule is arithmetic, and the guide to how often a septic tank needs pumping walks through it.

Does a Pocatello or Chubbuck utility bill show whether the house pays for sewer?

Usually, yes. Both cities bill sewer as a city utility alongside water and garbage, so a house connected to the city system pays for it on the same monthly bill. The reverse case is weaker evidence. City water with no sewer charge most often means septic, but only the billing office can confirm the account was set up right.

The City of Pocatello runs water, sewer and sanitation as municipally owned utilities and sets the rates by council. Chubbuck sends one combined bill near the end of each month, and its water and wastewater page lists a wastewater base rate among the residential charges. If you are not sure what a line on your bill means, the utility billing office for your city can tell you whether the account pays for sewer at that address.

A house with no city bill at all, on its own well, is almost always on septic. A house with city water and no sewer line on the bill is the case that catches people, because the water side makes it feel like a town house.

Is the round lid in the yard a septic tank, a sewer cleanout or the well?

A septic tank lid is wide and sits out in the yard, downhill of the house. A sewer cleanout is a narrow capped pipe, usually close to the foundation. A well is a casing standing up above the ground. Septic houses have cleanouts too, so only the wide lid settles anything.

Concrete tank lids run a couple of feet across and sit at the grass line or a little under it, so on plenty of older places there is nothing to see until someone probes. If a riser was added, the lid is plastic and at grade, roughly the size of a manhole cover, sometimes with a second one a few feet away over the outlet end.

The cleanout is the one people mistake for a tank. It is a capped pipe a few inches across, usually near where the main line leaves the house, sometimes with a second one farther out along the line. It shows where the pipe runs, not where it ends up.

A well casing stands up out of the ground with a cap on top, often with a wire or conduit running into it. That one is the well.

If you know it is septic but cannot find the lid, the guide to finding the tank itself goes through it in order, paper first and shovel last.

Can a house inside city limits still be on septic?

Yes. The city limit and the reach of the sewer mains are two different lines, and they do not match everywhere. Edge parcels and older lots that were county ground before the city grew around them can keep the septic system they were built with long after the address reads Pocatello or Chubbuck.

That is our judgment from how the valley grew, not a city rule, and we do not have a list of which parcels it applies to. What the state rules do show is that the situation is planned for. Idaho’s septic rules (IDAPA 58.01.03) let the state issue a permit on the condition that the system be abandoned by a set date or once central sewer service is available, so some systems were permitted expecting the sewer to arrive later. Plenty of permits carry no such condition. A city address does not settle it either way.

Which record settles it for good?

Two offices hold the paper. Southeastern Idaho Public Health keeps the septic permit files for Bannock County, and the city’s utility office knows whether a sewer service connection exists for the address. A septic permit on file, or a sewer account on file, ends the question.

The trap is reading a missing septic permit as proof of sewer. On an older acreage place, a tank that went in before anyone pulled permits, or a hand-dug system from decades back, leaves no file at all, and the tank is still in the ground. In that case the yard and the bill carry the weight, and if the house is being bought, a septic inspection pulls whatever records exist and opens the tank to confirm it is there. The permit-file step in the tank-finding guide above covers how to request the SIPH records yourself.

What happens to the septic tank when a house hooks up to sewer?

The tank gets pumped and taken out of service, never left full under the lawn. Idaho’s septic rules (IDAPA 58.01.03, section 007.22) make the property owner responsible for abandoning the tank and spell out how: disconnect the inlet and outlet piping, pump the scum and septage out with approved disposal, then fill the tank with earth, break it up, or pull it out of the ground.

The same rules count a system as abandoned once it stops receiving wastewater because the flow was diverted to another treatment system, which is exactly what a sewer hookup does. They also count one that has gone more than two years with no waste flow, which matters for a house that sat empty.

A few pieces we cannot answer from the rule book:

• Whether a house must connect once sewer reaches its lot. That is a city question, and it is worth asking before assuming either way.
• Whether Southeastern Idaho Public Health wants notice, a form or a sign-off for the abandonment. Ask them before the tank is filled, not after.
• What the city requires for the hookup itself. The connection permit and inspection belong to the city, separate from the tank.

The pump-out is the part we send a crew for. A tank being abandoned gets the same full pump-out as one staying in service, solids included, by a crew holding the Idaho DEQ pumper permit. Once it is empty and the lines are cut, the fill or removal is excavation work for whoever is running the hookup.