Complex (and problematic) plumbing under sink

28 Feb 2007
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United Kingdom
About 10 years ago, we had our kitchen redone.

Under our kitchen sink (see photos attached), the following are connected:
- waste from the double sink
- dishwasher waste
- washing machine waste
- condensation from the tumble dryer (small white tube coming down from the top)

(+ connections for mains water for all of the above)

The problem we have had, and it has become worse lately, is that food waste or gunk tends to block some of the pipes, especially the arrival of the tumble dryer condensation tube.

Is there any way we could simplify the connections and limit the risk of gunk/food blocking the pipes? I was for example thinking of running the tumble dryer tube separately outside the house.

Many thanks for any tips!

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I'd split them, run a new separate waste for the washing machine and tumble dryer, leaving sink and dishwasher on its own. Secondly, as Dan says, stop putting food waste down the sink. Drains are not dustbins, they are for water and human waste only. Water Companies spend millions each year cleaning out cr@p from sewers that simply shouldn't be there. It's blocking your pipework before it even leaves the house, multiply that by several thousand properties and see what you get! :eek:
The other point worth noting is that the main outlet is at the same level as all your appliance inlets, any restriction in the pipe will then lend itself to back flowing around the appliance inlets. Especially when more than one is draining at the same time.

As the chaps say, separate outlets would be the best option, increasing the main outlet to 50mm would also help and dropping the main outlet below the level of the appliance outlets.
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Many thanks for your pieces of advice. We will look at separating the outlets.

As it happens, I do not put any food waste down the drain and I use a sink mesh, but I imagine that some waste does inevitably build up over time (also from the appliances).
Periodically put a plug in the sink(s), fill with water, then remove plugs. This will flush the traps of debris. Also pouring the odd kettle-full of boiling water down each sink outlet will remove entrained grease.

Your dishwasher waste (the extreme left dark-grey hose) should rise and then fall before it connects to the main sink trap to prevent the possibility of waste water backflowing into the dishwasher (if its drain NRV should be passing)
On the plus side, 10 years is pretty good going for it to have only just started causing an issue... You must be very hygienic for it to have coped for that amount of time as it is a bit of a mish mash manifold :)

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