Toilet drain blocked for fifth time in two weeks

[gravesend46]

Probably gone beyond the point of DIY now but just after some advice on next steps.

A 1930s semi, with a drainage system shared with my neighbour. My outside excess/overflow drain next to toilet waste has been overflowing and he thinks both our toilet wastes join together beneath the drive to flow into main sewer system.

We've lifted up the manhole cover to the rear of property. Three pipes flow into that - one from guttering, one from kitchen/washing machine etc, one from toilet/bathroom. We've established the first two are flowing OK, no blockages.

The 'toilet pipe' - from both ends we've run drain rods through it, we've run an extendable pressure-washer hose through and my neighbour even attached a rope to the end to ensure we could get everything through the pipe. We've cleared the blockage each time but without any signs of any huge problem or bulk of material - though there has been a few unpleasant smells and an average amount of excess waste flowing through during each unblocking procedure.

But for the fifth time the drain is now overflowing again. I have a home emergency on my insurance so have rung them but they will presumably just send a bloke with rods who will do the same job we've already done (though hoping he can advise if he does have any ideas).

So I'm guessing there could be small subsidence beneath the drive or a sunken/fractured pipe - any other ideas? Do I call my buildings insurance next to advise or get a specialist in independently of them?

 

[piglet11]

As you are UK, the law on sewer maintenance responsibility has changed.
Your water company or whoever is shown on the bill as the waste water/drainage provider will now look at sewer pipes that were once classed as private sewers.
It used to be your responsibility from the boundary of your property to the property itself, but now, if a sewer is shared and runs in your gargen or whatever, the utility takes the responsibility.
On my property, the sewer for quite a few proprieties runs through the front gardens before it meets the main interceptor. It used to be the responsibility of the householders, now it's the utility's.
There's nothing to lose to ask and they will probably take a look for free.
Jetting companies will charge a lot for a camera survey and all they do is shift the problem further down the line.

 

[gravesend46]

Thanks, I'll give the water company a ring (the home 'emergency' people still haven't found a drainage company to send out in more than 24 hours).

My only thinking on the water company is that the main flow pipe (sorry, my terminology is probably wrong here!) beneath the manhole cover isn't blocked, the blockage takes place (as best I can tell) beneath the toilet wastes of mine and my neighbours presumably where the pipe joins, would a water company not simply say that part if my private land and no concern of theirs? (EDIT: just rang and they have said they will send someone out, as it constituted shared drainage -m or at east my description gave them that impression!)