Digging new foul drain through house

[Sparky1979]

We are in process of buying a house which we will undertake a fair amount of internal reconstruction on.

One of which is to move kitchen from small room at the front into a more open plan design at the back of the house.

I have solved most of the issues with electrics, gas, ventilation etc but the drainage problem is beating me.

Simplest answer would be to dig a new trench through across the inside of the house to the existing drain (which is obviously on the other side of the house!). I have spoken to a builder who seems to think this is feasible albeit at a price (£10k est?) and obvious mess issues. Mess is not huge concern as its a whole house renovation.

However, would a better alternative be to dig a new trench along the outside of the house on the side of the new kitchen and create a new link to existing public sewer? No idea if this is allowed or not?

I know a picture would be handy so I will try and knock something up.

All or any thoughts welcome ... Many Thanks,

 

[roy c]

Why dont you run your drain around the house with a series of manholes aslong as you can get it to fall into your existing drain...

 

[Sparky1979]

Fair point. Although surely that would be more expensive than a straight run through the house? Or are there other things to consider with the inside option that pushes price up?

 

[roy c]

The house I have got is a victorian 1880's house and I have a 6" old clay pipe that runs thru from back to front and it is doing the job but I dont think it is practical to do it nowadays. Where he gets £10 grand from to put a pipe thru I dont know. But running it in plastic with fittings manhole bases and collars and pipes shouldn't come to that and you can dig the trenches your self.

 

[Sparky1979]

Thanks so much for your advice. I was a bit taken back with that quote as well. I am an amateur in this game but I like to think no mug. Thanks for replying. Always appreciated

 

[Sparky1979]

Just realised the issue here is the house slopes from front to back (there is a step down in the lounge). Hence the new location for the kitchen and the waste will be belowexisiting drains. Try us I might to get water to run uphill it appears I cant fight gravity. The large cost of the drains is the builder factoring in having to dig so far down with all new drains. Back to the drawing board ....

 

[theprinceofdarkness]

Have you factored in the fall for plastic pipes (1:400?). Failing that buy a macerator (£400) and run the waste uphill if necessary in 22mm pipe.
Frank

 

[Sparky1979]

Its exactly the fall (which will be against the slope) that we are factoring in that is causing the costs. Digging deep enough to cause issues with the Northern line!

Have come up with possible solution. Running 50mm pipe through wall to external wall and around house to a soil stack at the front. Doesnt look great but its down the side without access so wouldnt be seen and as far as I know as long as pipes are vented there is no restriction on max length?

 

[ivixor]

For just kitchen waste, save yourself the hassle and expense and get a macerator. You can then run the discharge from that in the ceiling void to any existing soil stack.

 

[Sparky1979]

I did think of that but reading various posts on here it seems those in the know all consider them to be up there with the Devil...!

 

[maltaron]

If its only kitchen waste water (generally known as grey water) why not build a manhole outside the kitchen as a catchpit and use a submersible pump with float switch to your existing manhole.

 

[ivixor]

How bad they are depends on what will be in them if you have to unblock them...

Also with the small holes of a kitchen sink/dishwasher blockage seems much less likely.

 

[Sparky1979]

Thanks for your replies. Will look into this idea as ideally want the sink in an 'Island' so a macerator makes sense. "Sanisplit" seems to be the method of choice for most