Any ideas what this could be?

[Fern204]

So the house we are buying has this weird raised patio area, with an access panel, like a drain cover. We are planning to redo and landscape the patio/garden anyway, but anyone have any ideas? It's about 40 cm high, plus the 'decorative' wall. House has mains drainage etc, so not a septic tank.

Could have been built up so that the house owner didn't have regular overflow from blockage in the shared sewer.

The problem would be passed to the poor bugger with the next manhole down.

Manhole to the mains sewer? We’re in a 30s property and the sewer runs through everyone’s back gardens. We’re unlucky enough to have the access point in our garden - so when we built our decking over it, we included a trapdoor so it could still be accessed if necessary.

Looks like it could be access to foul drains - have you tried lifting the cover? If it is foul drains then you would most likely see earthenware pipes, with access for cleaning out blockages.

Consensus seems to drains, just wondering how we will deal with it being raised once we remove the surrounding patio. Time to call the builder!

If it is a foul drain, it should be below the original ground level (pre patio) as it will be relying on gravity to flow to the mains. If you lift the cover and it is a foul drain then you should find well below the raised patio level. The cover is just an access point - pipe work could be quite deep underneath it.

You can lift the cover and have a look. Also, think about where pipes from your house would be going to in a straight line passing through that inspection point - would it lead out to an estate road / main road?

I'd ask the current home owners in the first instance

She has asked them.