Outside open drain (gully)

mac456

Hi all,

I am just looking for some advice regarding our outside drain gully.

The drain grid is about 1.5ft below ground level and the drain itself is about 2 ft deep which has a hole on the right side wall which leads towards the main sewage pipes (I have had my hand down there)
This drain runs down the side of the house.

The drain collects waste from the kitchen, washing machine, upstairs bath and shower. It is also connected to the rain water pipes from the roof. The drain then flows to the main sewage line.

I have noticed when someone has a bath or shower the amount of water from either can make the drain fill up and the water will rise above the grate. It has not overflowed the hole yet though.
The water will then drain away fairly quickly back below the grid.

From what I can tell this doesn't happen when using just the taps or washing machines etc... only bath and shower (so a lot of water running though it)

Is this normal? Or is it blocked somewhere?

Thanks

EachPenny

It suggests a partial blockage restricting the flow through the drain. The small flows can drain away quickly enough, but the higher outflow from the bath/shower is slightly more than the drain can cope with so the water "backs up".

If the gully takes water from the kitchen sink then there is a good chance you have a build up of fat in the drain.

Ideally you want to look in the next manhole downstream of the gully as someone empties the bath - if the water flows freely in the manhole then you know the problem is between that and the gully.

Gullys usually have a trap, which is the most likely place for a blockage to occur. If you've had your hand down the drain and cannot feel anything, then rodding (DIY) or jetting (expensive) may help clear the problem. There are various chemical drain unblockers sold, I'm not convinced they are effective.

If you have drain clearance/repair insurance cover then it might be best to get them involved if you think it is a problem, but if the gully doesn't (yet) overflow it might be something you can leave for a while.

Davesnave

My thoughts are similar to the above.

If the gully itself is not roddable, I would borrow or buy a set of rods and rod it from the inspection chamber end, assuming it's not very far away. Fat is the usual suspect.

mac456

Thanks for the advice.
Unfortunately we have a shared manhole and the neighbours have access to ours so I cannot easily check this.

I have had the water board company come to have alook a few weeks ago (seperate issue) and all looked fine (main line)

Looks like I need to call a pro in.

chrisw

A shared drain is the responsibility of the water company, so you could always call them again if you think there’s a problem.

EachPenny

chrisw wrote: »

A shared drain is the responsibility of the water company, so you could always call them again if you think there’s a problem.

That's why it is important to find out if the problem is between the inspection chamber and the gully as this section won't (usually) be the water company's responsibility.

It is also worth noting there are some exceptions to "A shared drain is the responsibility of the water company" - probably not in this case, but a point that other people in a similar situation might need to be aware of.