Sink Drainage Problem - Very Slow normally but fast when under pressure.

[philleiper]

The sink is draining very slowly in my recently acquired 10year old Elnagh Sea Dinghy motorhome. I have run snake through it. Flushed it with mains hose , drained the tank. When under pressure with hose , or if I fully fill the sink it drains quickly but very slow if only normal a small anount of water in it. Shower room sink drains quickly. A little water appears to leak from top of tank when sink drains. I'm mystified , any explanation?

 

[lufcdave7]

Hi Philleiper,
We have a similar performance with our bathroom sink. It is caused by the routing of the waste pipe which creates a large 'u' bend where it passes under the motorhome chassis. This 'u' bend holds a lot of water, hence the heavier the water let out of the sink (i.e. a full sink) the quicker it seems to flow. With us it's not a problem, it has never frozen so we have not tried to alter it.

 

[n brown]

i have found that angled wastes often get an airlock when emptying and straight ones don't

 

[avandriver]

Yeah there will be a large bend in your pipe



Ooohh errr missus



Steve

 

[Deleted member 967]

In our Hymer all the waste piles are internal but after the initial drop from the sinks run level at floor level before going into the tank. Ours behave the same. Full sink quick drain, but a little water (ie. running a tap) and it backs up and drains slowly.

 

[philleiper]

Thanks for the feedback to all.

Thanks for the feedback to all. Sounds like that might be the answer as it seems too much of a coincidence. I can't come up with anything else.

Phil.