Downstairs loo - costs

[Paloma12]

Am moving into a Victorian terraced house. I would quite like to put a downstairs loo under the stairs. Can anyone advise me on considerations - might this be impossible, and what is absolute maximum cost? Am in London. Thank you!

We have done this exact thing in ours. It is well worth it!
You need to consider headroom first and also drainage as you need to know where pipes etc are going to go. Choose a corner sink to utilise space to the Max. Loo and sink needn't be expensive but amount of digging / drains etc will determine costs! Good luck x

Thanks for replying! How much did yours cost, if you don't mind me asking?

you presumably have wooden floors with a gap under them, and there is no concrete under the floors. In which case a new soilpipe can be laid over or under this floor, and run towards the drains.

I expect the soilpipe runs from the bathroom, on the outside wall, past the kitchen gulley. You might or might not have a manhole yet. You will almost certainly have one by the time you've finished. There will be brown salt-glazed pipes underground that your soilpipe and gulley connect to. These clay pipes will be cracked and broken and you will have to keep digging until you find something solid enough to connect to. This will be tiresome and nobody knows quite how long it will take or how much it costs. If you do have a manhole they can make a fair guess..

If you are unlucky some half-wit will have laid concrete over the underground pipes or manholes, or built a conservatory over them. This will treble your costs.

Start asking round for recommendations of an experienced local builder or sanitary engineer who has a local landline, and a real-world address that you can go and look at. Look at examples of his work and quiz the householders. Plumbers generally don't like digging up drains.

Under no circumstances have a Saniflow.

I just had new cloakroom fitted, but I have a manhole just outside the toilet - works cost 1200, materials around 600. No tiling, cheap vinyl flooring, white walls, Victorian plumb toilet and sink cupboard, new upvc window, relocating and hiding pipes. South London.

Thank you piglet john, and meadow. Meadow - would you recommend the person who did yours? Thanks!