Removing concrete waste collar on toilet

15 Oct 2023
Reaction score
United Kingdom
Hello everyone,
I am trying to work out how to safely remove this concrete waste collar, stick a 250mm deep 1m wide vanity unit on the wall behind and replace the toilet with a new back-to-wall toilet and hidden cistern.

Any advice on how I go about this and if I can likely get the new cistern and toilet to work with this waste pipe location if placed in the same position?

Help would be much appreciated!
Sponsored Links
If the collar encloses a cast iron pipe, when it breaks as you smash the concrete, you will have a chance to replace it with plastic, possibly nearer the wall to fit the location of the new concealed pan. If you manage to keep it in situ, you might have to build a frame behind the vanity unit so everything lines up.

IME more likely a clay pipe

And the concrete poultice was probably applied to hide a crack or break.

Prepare yourself for some digging

Where is the nearest manhole?
Can you get under it and grind off below the collar and add a rubber sleeve.

Sponsored Links
get the new cistern and toilet to work with this waste pipe location
What type of new toilet is it? If it's a close coupled system with a rear facing spigot then little chance with the soil pipe that far from the wall. If you have managed to get an S-Trap (downwards facing spigot) pan then you need to measure the spigot centre against the back of the cistern to see if once the pan spigot is connected to the soil pipe that the back of the cistern will meet the wall. Again, you'll be very lucky if it does, hence why the old one was a low level cistern

As others have said, that will be a clay soil pipe in the floor and it would need cut flush with the floor and then a 4" pan connector would usually fit. It would look like this if you got all the mortar out
Thanks for the input everyone, the floor is concrete underneath these nasty green asbestos tiles.

It seems like I need a professional to come out and have a look at whether a normal toilet will be able to suitably connect to this waste outlet then!

I’m not in the trades myself so I’m relying on tradespeople/friends for guidance.

I was thinking of buying the bathroom furniture and bringing it in to see how it may all fit. That was I can see if the S-Trap type connector will get down to the floor based waste outlet.

I guess for now I need someone to have a go at grinding off the concrete, low level or below level to allow for a connector?

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links