Septic Tank/ Soakaway / who knows??

[Rubbish@DIY]

Brought a house built in the 1950s which is connected to main sewage in the road. We have no plans etc for the house as it was brought from the bank.

For context: on the road is a manhole cover, comes back to another manhole on our property, the pipe continues to go back towards the garden but also has a pipe to bathroom. Everything seems to drain down to the road.

We were originally told we had a potential soakaway but today found a leak in the back garden today, about 20m back from manhole cover. Seems to be clay pipes that have broken, clear water is consistently trickling out into the hole we'd been told was a soakaway. Have been advised its rain/drainage water. *it has no smell

Had jet wash to check pipes were clear further up before repairing obviously broken pipe sections. Hit something and have now been advised we have a septic tank which is why it's blocked and will now require further investigation.

That doesn't make sense to me as I thought a septic tank was for waste not rain drainage? Surely we wouldn't need a septic tank if we have main sewage? I'm so confused and hoping someone can help explain please? What are the pipes under the manhole cover and why would I have pipes going back into my garden?

Would we just need to divert the leaking section into new pipework and a soakaway?

Thank you

 

[Burnerman]

If the property was mine.....
Lift the lids on the inspection covers, flush the loo, run the taps in the bathroom and kitchen and see where the water goes.
Next, push a hose pipe down the rain water gullies and see, as far as you can, where it goes.
Dyes are available to help if you feel it’s needed.
At this stage it would seem you have a main sewer drain, which is good, and rain water soakaways.
John