I've been doing some work in the galley on my little boat and then wondered about why the kitchen and utility room sinks at home have traps. On the boat the 'grey water' simply goes straight out of a hole in the side with no trap.
All the domestic sink wastes I've ever come across simply have an open ended pipe that discharges into a grid, usually shared with the gutters. So why do they have traps? They're not connected directly into the sewers.
The pipework from my sinks goes into a boss on the internal soil/vent stack.
I suppose you don't get sewer smells finding a way back to your galley from a canal/river:-)
And there is one reason why sewage treatment plant is overwhelmed every time we have persistent rainfall! Much more convenient for housebuilders than soaks.
>
When you drop something dense down the sink it collects in the trap. That's likely saved many a wedding ring. It also prevent blockage further down - I retreived an electric toothbrush head that would have caused a more serious blockage in the waste pipe.
Theo
To stop smells, primarily, because domestic waste water frequently discharges into foul drainage. A trap will also stop insects.
It's not correct to say that rainwater and waste water are mixed. They are supposed to be separated to prevent rainwater from overloading the sewers.
While it is standard practice for anything new build, there are plenty of Victorian era properties with combined sewers that take black and grey water.
In some cases they do connect directly into the soil /sewage pipe.
Even if to an open ended pipe the open nearby drain may still be a bit smelly
That may depend very much on the age of the property. In my 1908 property all then water, sewage, bath, kitchen and rain all went into the same pipe. I have now changed the configuration so that the rain ends up in flower beds either by running straight in as a soak away or via water butts - with the water butts overflows draining to the lawn.
Ditto
At least on the main kitchen. I installed a grate on the spare kitchen. Everyone shrugged, Including the building inspector
Its a choice.
The grate thing has a trap itself
Illegal to have shared gutters and sewage in new builds
Even if not smelly, it stops a draft blowing out the plug hole - this closing another air leak between inside and outside.
I thought there were still exceptions for non-porous ground and where SuDS Ponds were impracticable?
BICBW
Oops! you're absolutely right, of course ... I'd also forgotten that, because the ground wasn't suitable for another soakaway, I was allowed to run some rainwater into a foul drain at my last house.
Draught. Insulates from cold air entering house, allowing that most people won't be leaving their plugs in the plug hole.
I can think of better ways of not losing things down the plughole though.
Yes, OK, ours is a house built in the 1920s or 1930s so the gutters do go into the main drainage.
Not as far back as that, our 1920s/1930s house has everything going into the sewers.
Well as far back and further :-) Not sure when the change in policy happened though, or if it was a national or local thing. First house (~1890s) was combined, second (1956) was separate, current one no mains drainage.
If I give you a red pen, could you do a squiggly underline as I type?
Nowadays, yes. But that was not the decision in Victorian times, which is why there is a huge legacy of shared pipework, and why there continues to be so much spillage.
I'm not saying the water companies are blameless, mind. Large organisations (public as well as private) tend to have a "protect themselves" mentality, as the Post Office and Infected Blood scandals show.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required