Septic or sewer? How to tell, and what your town actually has

Five ways to tell, for your own house

1. Read your bill. A sewer or wastewater charge from a town, an MUA or a sewerage authority means public sewer. There is no such thing as a bill for using your own septic tank. This settles it more often than anything else on this list.
2. Look for the lid. A septic tank sits roughly eight to fifteen feet from the house, and there is normally a lid or an inspection port at grade or just under it. A metal detector or a probe finds it quickly if the yard has grown over.
3. Watch the lawn. A drain field behaves differently from the rest of the yard. It greens up sooner, dries first after rain, and in a hard frost it is often the strip that thaws early. If part of your lawn has always been odd, that is frequently why.
4. Find the cleanout. A sewered house usually has a capped cleanout near where the lateral heads toward the street. A septic house has its access on the tank side instead.
5. Ask the town. The municipal construction or health department holds the septic permit if one was ever issued, and the sewer connection record if there is one. Your closing documents often name the system too.

If you have just been told there is a problem with the line either way, our post on what a failed sewer scope really means covers which camera findings are serious and which get oversold.

What your town has

New Jersey publishes both halves of this and never puts them together. NJDEP maps where public water is actually delivered, and separately maps where sewer service is planned. Joined against municipal boundaries, the two of them sort every town into one of four situations.

Note the last box. Not one municipality here is well country with public sewer, and that is the most useful single fact on this page. Public water arrives first and sewer follows the places that already have it, so if you are on a well you should expect to be on septic.

How to read this without getting it wrong

Both numbers are shares of the town's land area, not of its homes. A dense borough center can hold most of a town's houses on a small share of its acreage, so a town reading low can still have most residents served. Expect the wells and the septic systems to be the outlying properties on the bigger lots.

And a sewer service area is a planning designation. It marks where a county wastewater management plan says sewer service is planned and permitted. It does not say a main runs past any particular house, and plenty of properties sit inside one on septic for decades. Proposed treatment facilities are excluded from these numbers entirely, because counting a plant that does not exist as service would simply be false.

6 municipalities have no mapped public water delivery area at all: Sandyston, Walpack, Hardwick, Hope, Knowlton, Liberty. That does not mean every property there stands alone. A system serving fewer than fifteen year-round connections falls below the threshold the state maps, so shared wells and small association systems exist without appearing anywhere. 12 have no mapped sewer service area at all: Califon, East Amwell, West Amwell, Ogdensburg, Sandyston, Walpack, Blairstown, Hardwick, Hope, Liberty, Chester Borough, Chester Township.

Why it changes what work costs

On sewer, you own the lateral, in most New Jersey towns all the way to the main under the street. A repair that stays in the lawn and a repair that reaches the road are different jobs with different bills, because the road brings an opening permit and municipal restoration with it. On septic, the tank, the distribution box and the drain field are all things that must not be driven over, built on or trenched through, and the system is regulated locally under N.J.A.C. 7:9A by your municipal or county health department rather than by NJDEP directly.

And if the sewer has reached your street and you are on septic, the question stops being which one you have and becomes whether to switch. That job runs $15,000 to $35,000 here, with a separate connection fee from the authority on top, and the whole breakdown is on converting from septic to sewer.

There is one more thing worth knowing before any machine arrives. New Jersey's One Call rules define an underground facility in a way that expressly excludes gravity sewers and storm drains, so your sewer lateral is never marked out. Water is marked, sewer is not, and somebody has to find it another way. That is covered in how a line actually gets replaced.

Questions people ask

Sources

• NJDEP Purveyor Service Areas of New Jersey, NJDEP's mapped public community water purveyor delivery areas. NJDEP is explicit that these are delivery areas and that franchise areas are not depicted.
• NJDEP Sewer Service Areas, NJDEP's mapped sewer service areas, retrieved 2026-09-08.
• Both joined to US Census 2020 county subdivision boundaries to produce a share of each municipality's land area. Slivers below 0.08 percent are dropped as boundary noise.
• Septic systems of 2,000 gallons per day or less are governed by N.J.A.C. 7:9A and administered by the local health department, municipal in some towns and county in others, rather than by NJDEP directly.

State files lag reality, and we would rather say so than pretend otherwise. Reviewed 2026-08-28. This is general information and not a determination about your property. Your municipality, your utility and your local health department have the final say.

More on water specifically in who supplies water in your NJ town, and on septic capacity in septic density across Sussex County.