Drain Query

[securespark]

Have had a problem today with a blocked gully.

Managed in the end to unblock it with the pressure washer.

But I was well confused about the drainage situation.

Our house has a manhole in the driveway at the front but this is only for rainwater.

The main sewer is at the rear, running through everyone's gardens around 2m from the back wall. There is a manhole in the garage which connects to our stack and next door's and runs to the main sewer in the back garden.

Confusingly, into the blocked drain feed two drainpipes and the condensate waste from the combi, along with the sink and DW wastes.

And a few feet away, there is a rodding point with an aluminium cover. I initially thought the blocked drain linked to the rodding point, but could not feel a T in the pipe.

I shoved 3m of rods down the rodding point. The rod seemed to go fairly straight towards the front of the building. It stopped at 3m, maybe due to a bend.

Then I focused on the drain, pulling out loads of lumps of mortar and then fatty goo. It felt like soft birds' fat balls (fnarr, fnarr!)

I could see there were bubbles when I did this, accompanied by a trickling noise, so I knew I was on the right path, but I could not reach far enough with my fingers to dislodge more goo.

That is when I admitted defeat and tried the pressure washer.

Before that, I was considering dismantling the pipework on the left hand side of the drain and looking underneath (the mortar was loose).

So, my questions are:

Where does the pipe from the rodding point go?

Does the blocked drain link to the sewer at the back?

The house was built in 1960ish. If that blocked drain is connected to the surface water drain at the front, I guess it's not to regs to have waste water emptying in it?

How do those "dual" drains work?

Do they have some kind of a trap built-in?

Here's the drain:

And the rodding point a few feet to the left:

And a diagram of the drains:

 

[blup]

So, my questions are:

Where does the pipe from the rodding point go?

Maybe a redundant layout.

Does the blocked drain link to the sewer at the back?

It sounds like a combined sewer connection.

The house was built in 1960ish. If that blocked drain is connected to the surface water drain at the front, I guess it's not to regs to have waste water emptying in it?

You could put drain dye in to confirm the route

How do those "dual" drains work?

Do they have some kind of a trap built-in?

I believe the gully is trapped which is where your blockage seems to have occurred

 

[securespark]

Cheers, blup.

The reason I think it's not combined is that the stacks are linked to the manhole in the garage (which runs to the back of the house) and the rainwater drains to the manhole at the front of the house.
United Utilities confirmed this when they came to deal with a blockage at the back of the house.

But I will happily run some drain dye through at several points to try and determine where it goes.

If it is a segregated system, is it OK to use drain dye in the rainwater drains?

And why is one side mortared in and the other not?

Is it the case that these drains can be used on either system?

Thanks.

 

[blup]

Cheers, blup.

The reason I think it's not combined is that the stacks are linked to the manhole in the garage (which runs to the back of the house) and the rainwater drains to the manhole at the front of the house.
United Utilities confirmed this when they came to deal with a blockage at the back of the house.

But I will happily run some drain dye through at several points to try and determine where it goes.

Worth trying

If it is a segregated system, is it OK to use drain dye in the rainwater drains?

Yes because how could you otherwise tell unless you get a cctv done

And why is one side mortared in and the other not?

Not sure what you mean

Is it the case that these drains can be used on either system?

I believe there are rules in place about mixing them unless you can show there is no practical alternative

Thanks.

 

[securespark]

Not sure what you mean

The drain has two sides that are segregated from each other. The left side has the sink waste emptying into it and is mortared in place.

The other side has a grille with pipes terminating just above it.

I was wondering if the left side emptied to the sewer and the right side to the rainwater drain.

 

[Nige F]

It's just a long hopper with one side mortared - like an oblong funnel with a trap under

 

[Hugh Jaleak]

Absolutely no way of telling where the drain run, without surveying or testing. Even the drawings aren't always correct.

Dye is fine in surface water, just don't go mad with it, or your local stream may turn a lovely fluorescent green. Needs testing ideally, if grey water is going into a rainwater drain it needs changing before the Water Co find out. What doe the rainwater downpipe going into the gully take?

Lastly, hopper would look similar to that in the pic. Wastes are put into one side and then sealed in with mortar, partly for aesthetics, partly to allow the waste to discharge into the hopper so detritus doesn't block/foul the grid, and other side is then fitted with a grid to keep large debris out and allow a visual inspection of gully for maintenance purposes.