Septic tanks or cisterns?

We’re having sewage adventures at my house today. Frustrating, extremely expensive sewage adventures. That is not the point of my post, but as long as I’m shelling out I’m going to milk it for all the sympathy I can get.

So while the backhoe was digging up my yard to find where exactly the sewage lines run, they uncovered two lidded terracotta tanks about 5’ underground. The tanks contained dirty water. The workmen said they were ancient illicit septic tanks and hurriedly covered them back up so that the county inspector wouldn’t see them and add a few more thousand in removal fees to our bill. I got this info second-hand from my husband who was present at the time.

I’m questioning whether these are septic tanks or water cisterns. I was hoping someone here would have a better base knowledge of the evolution of plumbing and sewage systems.

The 120yr old house I grew up in had a spot out back where the outhouse used to be, as evidenced by the abrupt sidewalk termination flanked by two rosebushes. There were also two capped off water cisterns closer to the house that fit the description of the tanks in my yard.

My current house was built in 1810. The tanks in question are about 20yds, diagonally, from the house, and are piped back toward the house. I know from the previous owners as well as the neighbors that the sewage from the houses on this street used to run through pipes to a stream in the back yard, collecting in what is now a pond but was once an open cesspool. I am grateful for modern municipal sewage treatment! So if they had this easy, inexpensive (disgusting) system, why the septic tanks? Unless they had them in between using the cesspool and getting municipal sewage.

I want them to be cisterns because the county won’t make me dig up cisterns. Not that they will ever know about them at all, mwa ha ha ha! So - any historical sewage experts (if I can’t find them one here, I can’t find one anywhere) around want to back me up?

I don’t know, but, why would the county force you to do anything with them? They wouldn’t have been much of a hazard while in use, and couldn’t be any hazard at all now, could they? If they were big buried flower pots, would the county care about that?

I vote cistern.

Were there any pipes in/out? The only example I have seen of a cistern was childhood home (1915) which was on city sewer from beginning (as far as we knwe) The cistern was a brick-lined hole in the ground with an iron “man hole” fitting on top. No rememberence of how water got in (the roof runoff should have been routed into it.
The depth is bizarre, and is the big hint of septic use - but, what got in, and how? Unless there was a large diameter pipe in, and at least holes in the sides for discharge, I don’t see septic. Thwy whould big the expensive (and counter-useful) way to build an outhouse (why line the hole wth waterproof material,.fer crying out loud?
But, the workmen have a much better knowledge of local custiom (however bizarre and counter-intuitive) than I.

The usual reason for removing (or filling) is safety - prevent small children from falling in. Once buried, however, I see no threat.

No, the reason is to collect fine money. Once you pay the juice you’re fine.

The ancient illicit tanks would need to be connected to a leach field to function in a septic system, or constructed in a manner that leaks and be in very porous “perky” soil. Can you see any of the internal porting?
That they contain water MAY be an indicator of cistern use, but they could be full for a number of reasons including hydrostatic pressure. Removing them shouldn’t be necessary, just vaccing out and filled with sand, gravel etc. Do find the inlet.
The slope and size of any connecting piping would be a good indicator of their use. Perhaps that’s what you mean by “piped back toward the house”. If they are septic tanks the house would have to be higher unless shit ran uphill in the old days.

I missed the call. But a few years back a woman had to be extricated from a caved in cesspool.
I would have anything like that filled in for safety like Derleth posted.

I prefer the Brethren myself.

To answer a variety of questions, there were pipes leading from the house to the tanks. The house does sit higher than the tanks, but the lot as a whole is sloped (like so many in the area). The existing sewage lines run toward the tanks, but then so do the drainage pipes from the downspouts. All the old terracotta piping in the yard was the same diameter, which confused the sewage guys for a minute until they figure out which was grey water and which were sewage. (fortunately we’re not one of the illegal “greywater into the sewer” problem properties) There’s no way to know which line had been connected to the tanks.
As far as how far down they are, I suspect there was a not insignificant amount of grading done when they built the garage. It sits between the tanks and the house, and unfortunately *over *the existing line from the house to the clean-out. So they may not have been so far down.

Thanks for all the replies - we may never solve the mystery (mysteries abound in a house this old), but at least I know I’m not way out in left field on this one.