Bit of a strange one this, we had an extension last year with a down stairs shower room put in.

After a period of frequent use the shower drain starts glugging and it overflows from the grid outside onto the path along side the house. It’s our path so no neighbour/ highway issues.

If I lift the little man hole over the drainage system you can see all the pipes are clear down stream. If I run a hose down through the manhole the water flows away.

The way to alleviate it is to put a rod with the plunger disc attachment up the pipe towards the drain, you then get a little pop and the water runs freely from the shower drain once more.

It happens roughly every 4-5 months

Any clues?

Hi, If you look at the outlet in the shower tray the top chrome cover (about 100mm dia.) can be removed by gentle wiggling ( technical plumbing term) to expose the trap. The centre of this can be lifted out for removal of accumulated hair etc. No tools required.

Done that and it doesn’t stop it

Sounds like you have insufficient fall on the section of pipe between the drain and the manhole, perhaps even a slight rise somewhere which is allowing a bit of an airlock to form.

Sounds like you have insufficient fall on the section of pipe between the drain and the manhole, perhaps even a slight rise somewhere which is allowing a bit of an airlock to form.

Marvelous, if it’s anywhere it’ll be between the trap and the outlet through the wall as the drain pipe definitely falls away from the grid

There may be a little blockage of hair and soap scum which has got past the trap and is adding to the problem. I’m guessing you’ve tried the normal kind of chemical unblockers, but if not, might be worth a go.

Get the builder back. Do not waste your time.