Proposed layout - is it viable?

[buffster]

Hi there, first time poster, so apologies if this is not an appropriate question or is poorly formated.

I want to make some changes to my flat, basically adding an ensuite and moving the kitchen. The flat is a ground floor terrace with just one flat above sharing the same SVP. All current drainage is through the one SVP located in the corner of what I hope to make an ensuite.

Early stages yet, as I'm only trying to sort the plans out before submitting them, but I am trying to find out what is viable before getting too far and then discovering that what I want to do is impossible.

I understand I can use a collar boss to get water into the stack just below the toilet waste, as this would be necessary due to the low level coming from the bath and shower. My main concerns though are as follows

1) Can I connect the two toilets on the same pipe to the stack (red pipe on diagram)?

2) Is there a limit to how many things I can join together using say 50mm pipe? Could I run just one pipe from the kitchen for the dishwasher and sink, then join the bathroom basin, then the bath, then the washing machine, then the shower, then the second basin, all discharging through the collar boss (yellow on diagram)? This would require the fewest number of pipes, but I suspect it is way too many things on one pipe. I know I would need to fit the anti syphon valves to prevent traps being emptied, but I can't seem to find definite answers as to what you can and can't join on the same waste pipe.

A realistic alternative would be to run say the kitchen sink, dishwasher and bathroom sink in one "higher level" pipe, and the bath, shower and washing machine in a "lower level" pipe with the ensuite basin separate or joining either of those. Although requiring twice the run of pipes, would this be acceptable if the first option isn't?

Hopefully I've managed to attach a diagram illustraing the proposed layout, I hope it all makes sense.

Any advice much appreciated.

PS I've just previewed this post and the diagram appears to be a thumbnail, hope that is OK

 

[justlead1]

Hi Have you considered extending the drain from the manhole, so as to form a stub stack or fitting a back inlet gully. As a means to discharge the numerous waste pipes?

 

[Bernie2]

Hi!

Have a look at Bldg Regs Approved document H drainage for guidance.

Off the cuff, one of the biggest problems is linking low level wastes i.e Bath or shower to high level wastes such as washbasin or sink. If you get a blockage it comes up in the lowest of these first.

Also you may very well get back pressure up some branches. Most people seem to think an air admittance valve cures all ills. The reality is far from it, they may stop traps getting sucked out but can't do anything against them getting blown out.

As far as I know they simply don't make internal vents, although you can vent a line higher up into the same svp stack once past the highest connection.

A 100mm svp can take a lot of appliances, at a rough guess your discharge unit loading comes nowhere near its maximum.

If you Google drainage "discharge unit values" and "drain ventilation" you will probably get loads of info that you want.