Manhole in the garden: what could it be? ... (Pic attached)

[Sandrine1982]

Hi,

So we've just viewed this house and we plan to make an offer.

We liked the house but the garden is a bit ugly and needs work.
There's also this manhole in the middle that we're concerned about. How common is it to have a manhole in the garden? What could it be??

I'm not worried about the aesthetics as we would cover it with decking or something like that. But are there any other issues that we should be concerned about?

Thanks in advance.
x

We have at least 4 (haven't seen them for a while) on our driveway in assorted shapes, which is why we have stones rather than pavers or tarmac. Lived here nearly 30 years and nobody has needed to access any of them.

There are three in my garden, my house is built on what was allotments so I think there used to be communal taps.

It doesn't smell, I just have a large pot plant on top of the one I can see, the others are quite hidden.

Take it up and have a look, fhen you will know for sure. Normally they are just so you can check the sewage pipe, and no they don’t smell, they’d only smell if there was a problem with the pipe in that area, but man hole cover or no man hole cover that is the same anywhere.

We have a manhole in our garden. Yorkshire Water come and check it every few months for some reason I don't really understand. But it was all listed in the searches.

We’ve just found one in our front garden lawn in preparation to level the lawn. As we began to dig we hit stone, the wall of a manhole, no top at all and filled with soil and very deeply, should I just continue to dig to see what’s at the bottom?

It's completely normal. We have three, for accessing various junctions where drains meet.

They're useful as if anything gets blocked you (or the drain person) can locate the issue and unblock itore easily. There shouldn't be any smell: the covers close tightly and there can't be any real pressure in the drain such as would push the smelly air out.

You can hide them if you need to - one of ours is in the middle of the driveway and has a cover with some of the block paving set into it so it blends in. The other two are down the side of the house and are just normal black covers.

NB: my post above is assuming the cover is for a drain. It could be something else though, in which case ignore much of what I said!

If you didn't have a chamber that flooded the garden when the pipes became blocked it would flood inside the house instead!

I like what they've done with the garden

This is so vanishingly unlikely it made me chortle.

op it’s very common, you can open it if you please, irs just to inspect the sewage pipe.

Mum has a manhole that links 8 houses. Keep it accessible - she's had issued when neighbours have flushed nappies or created fatbergs. Maybe disguise it with some moveable pots.

We have one front & back. In 14 years we've never needed access. We have decking over back one but I is we could unscrew a section if needed. Ours seem to just be water channels

Zombie thread

We have one in our garden, it's the waste pipe for the road. It doesn't get smelly at all, but it does need to be easily accessible for emergencies. I'm 25 years in my house and never needed it to be accessed though we do have easy liftable decking in it, just in case.

Well it shouldn’t make you ‘chortle’. I am an HSEQ with 30 years experience in underground utilities and ‘unlikely’ or not, there is a chance -
one I have seen unfold more than once - and one you don’t take a risk on.

To reply, not reply to the OP as this is an old thread, but to answer the question of the subsequent poster - you have an underground void but within no cover? Is that current? You say filled with soil and filled deeply?

when you purchased did you get water records showing waste water routes? Can you see anything in terms of depth? What is holding the soil up?

Hello, this is what's in my garden - any ideas what it could be?! And whether connecting a soakaway for rain water to drain into would be an option? Thanks!

The thing on the left in the first photo looks like a vent for a soil pipe. Next to it is a perfectly ordinary-looking "manhole cover".

I would expect there to be an inspection chamber for a drain connected to either the foul sewer system or possibly, given it looks to be of significant age, a combined (foul+surface water) sewer (these are still a thing in some areas but aren't built any more as they tend to result in untreated sewage overflowing into rivers, lakes, the sea or onto the streets during periods when unusually high rainfall exceeds the design capacity of the sewer.

These days vents are usually provided at the top of a soil stack, so that any odours and dangerous gases dissipate high up, but a fair few older houses round my part of the world still have these low down vents near the edge of the property where the drains connect into the sewer system.

I'm not quite sure what you mean by "connecting a soakaway for rain water to drain into". A soakaway is an underground chamber usually filled with stone which is used to temporarily store surface water runoff while it permeates into the ground. You might connect downpipes from the guttering to a soakaway instead of connecting to a surface water drain and thence to the sewer system. If you have a soakaway then this is the end of the line: water goes there then dissipates away. You don't connect it to a sewer.

If you don't have a soakaway and you're looking for somewhere to drain surface water to, then building a soakaway would usually be a preferred option. Otherwise it would drain to a surface water sewer if there is one in the vicinity. If this is a combined sewer then you could possibly discharge surface water to it if your street has no separate surface water sewer. If this is a foul sewer, then you shouldn't (must not) discharge surface water into it.

That depends where you are in the country. Our rainwater all goes into the same pipes as the foul drainage. It's the same for the whole city.

I know! That's why my post specifically discusses the differences between foul sewers and combined sewers which carry foul+surface water and are "still a thing in some areas" (like yours). 🙂

I used to work as a sewer rodder. I’ve never once in my life used a gas detector just for lifting a lid, only if I was actually entering a sewer. Never seen a labelled manhole either, any markings are just the stamp of the company which made the lid.

But yes, I’d lift it to see what diameter pipes and which way they’re running and to see if it’s surface water or sewage. Failing that ring the water company as they will have electronic maps and should be able to tell you. And I wouldn’t deck over it.

I was about to come on and say I wouldn’t personally buy a house with one of those in the garden - then remembered we’ve got one too!

We have a large garden and it’s flush to the floor in the middle of a stone patio area - ive never even thought about it before, lived here 20 years! I must ask dh what it is..

Whoops. Sorry missed that! Not fully awake this morning

Not a problem! 🙂

OP: I forgot to mention that we didn't think our old house had a manhole in the garden until the drains needed unblocking. After a bit of detective work the drain people figured out there should be one under the drive. It turned out a previous owner had laid block paving over the top of it!

So, one more reason not to rule out a house for having a visible manhole: it's better than a hidden one!!