Depth of a sewer pipe?

I wasn't sure if this comes under building or plumbing, but I've noticed similar questions on the building forum so assume it goes here...

Was there a standard depth to bury a shared sewer pipe in the 1920s? If so, what was it?

I live in a 1920s semi. The main sewer runs down the middle of the road, and I have a shared pipe with my neighbours from the back of our houses to the road. The exact location of the pipe seems to have been lost in the annals of time and didn't show up in the searches, but I do know we are still using the original pipe.

Yesterday I noticed that the brick wall on the boundary between me and the neighbour appears to be resting on a very wide foundation... I was wondering if that indicates it is above the sewer pipe (either as a protective capping, or as a "float" to spread the load either side of the pipe).

I would like to be able to dig down to sink a gate post, but obviously don't want to crack open a sewer pipe! But, at least if I know where it is I can rethink my plans around it.

No set depth unfortunately so it's hard to tell where the sewer is without having a look for it.

Are there any manholes around which might give an idea of the line of the sewer?

At least if you are digging to concrete the post in it shouldn't be too much of a concern, just go easy with the pick

No manholes unfortunately. The house was built not long after WW1 so I think they were still working out the practicalities of indoor plumbing and its maintenance.

The water supply is shared too, no street level stop-cock... thankfully it's fully-plumbed in copper.

Is there likely to be a minimum practical depth below the lowest toilet? I still have the original WC room, the WC outlet goes through 90 degrees down into the floor and from there I have no idea.

Assuming a 2.5 degree fall, the pipe will have dropped 20cm by the time it reaches the place I want to put a post... dunno if I want to try that theory out though!

NO MANHOLES There must be one buried somewhere Have a search for Section 24 Sewers on a search engine. Sets out who owns what and who pays. That age of house you should be OK with the Local Authority owning ( adopted) the pipework. Don`t take any C-Rap from them or the local sewerage co. I just got a rebate from S*uth*rn Water because I have NO stormwater connection to my house What a load of Bull they presented me with, until I said ...Come and look @ the Dirt road at my frontage, and show me the road gulleys/ Storm sewer. 20+ new neighbours to tell the news to - down here in the sticks. LOL. I am the Neighbour From Hell...IF you`re a beuracrat or a poxy door to door hawker

Well, I've found a manhole... It is in the centre of the carriageway (of a rather busy B-road!) which makes sense as the only thing the surveys showed was that the sewer runs down the centre of the road. But, it doesn't line up with any of the houses on the street so I can only imagine the sub-sewers (for want of a better word) just dump into that main sewer, and the manhole is access to the main sewer.

Thanks for the tip on adopting, I'll dig out my searches and check if it says who owns what pipe.

In the meantime I think I'll be digging with a trowel to see if I hit anything!!!

Thanks for the help guys.