Common kitchen and bathroom drainage

[DNJ]

As part of a phased kitchen renovation we are looking to move the dishwasher to the other side of the room. Eventually the sink will move there as well and we may have to punch through the external wall to connect to the existing SVP, but for now we're hoping there's a temporary solution:

The bath is directly on the other side of the wall. Is there any regulation and/or practical reason why we can't join the dishwasher drain to the bath pipe? Would the answer change if we added the kitchen sink as well? Photo of bath pipe attached and the wall we would come through on the right.

I say this is temporary, but it could be more than a year before we get round to the other.

What do you think?

 

[jj4091]

The only thing I can think of is if the waste blocked outside then your dishwasher would pump up into you bath.

 

[Madrab]

No real reason not to, as long as the bath waste run is nice a clear then it shouldn't pose any issues, especially as the bath is properly trapped. Only thing I would watch out for is if the bathroom basin is on the same run then you maybe want to check it has an anti vac trap to stop the trap being pulled.
If it going to be for an extended period then make sure the waste run is flushed with a sink full of boiling water/strong detergent mix once a month, just to keep everything nice and clean and free running.

 

[JohnD]

... make sure the waste run is flushed with a sink full of boiling water/strong detergent mix once a month, just to keep everything nice and clean and free running.

Won't the dishwasher waste do that?

 

[DNJ]

Won't the dishwasher waste do that?

I think it's dropped in temp quite a lot by the time it's flushed, not quite as effective perhaps?

 

[Madrab]

Won't the dishwasher waste do that?

Not in most cases, if you have ever seen a washing machine/dishwasher waste after time, it invariably gets really badly gunged up.

If everyone used the machines/sinks correctly then there probably wouldn't be an issue but unfortunately they don't. Too much detergent, too many food debris, machines running on energy saving low temps etc. The waste runs never get a good hot flush out. That's why I always recommend to every client of mine run a sink/basin full of boiling water with something like a floor cleaner in it, to flush all their waste pipework out, more so in low volume waste runs that serve showers and basins. It goes a long way to keeping everything clean and clear. Also recommend a yearly clear out of all the accessible traps if they can and demonstrate how easy it is to do.

 

[DNJ]

Not in most cases, if you have ever seen a washing machine/dishwasher waste after time, it invariably gets really badly gunged up.

If everyone used the machines/sinks correctly then there probably wouldn't be an issue but unfortunately they don't. Too much detergent, too many food debris, machines running on energy saving low temps etc. The waste runs never get a good hot flush out. That's why I always recommend to every client of mine run a sink/basin full of boiling water with something like a floor cleaner in it, to flush all their waste pipework out, more so in low volume waste runs that serve showers and basins. It goes a long way to keeping everything clean and clear. Also recommend a yearly clear out of all the accessible traps if they can and demonstrate how easy it is to do.

Good health tips!

The external junction of our washing machine/dishwasher and kitchen sink is pretty clogged up and leaking down the external wall. It's 7m up though so it'll be a scaff job unfortunately. If we and the previous occupants had done what you say it probably would've prevented the build up!