# Shower Slow Drain



## Joeo's (Dec 11, 2016)

Maybe someone can guide me with my Hymer 534 (1998 -Round lights model) shower waste question. 
Shower tray drains very very very slowly in normal use, i.e. drains slower than water from shower head flows into the tray. It will overflow if allowed to reach that level. The hand basin in the bathroom is similarly slow.

Investigated the Waste Pipework with great difficulty and found absolutely no blockages or obstructions.
By accident, I discovered that when the waste tank valve is open, (to dispose of the grey water from the waste tank) the shower tray and hand basin empty quite quickly.

So am I correct in assuming that the air in the tank is stopping the water from flowing in, except very slowly?
If so, should there be a vent of some sort in the waste tank to let air out as the waste water enters?

I looked under the van to try to find such a vent and perhaps check it for blockages. 
Phew.. not so easy; found tank is inside another tank, presumably to prevent freezing. No obvious vent and no obvious access to to tank to allow one to be added.

Am I on the right track regarding the cause of the problem? Anyone experienced this problem and found a solution?
Thanks in advance!
Joe


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## jiwawa (Jun 22, 2007)

I've a similar problem. I notice if there's a lot of water in the bathroom sink it drains faster. I've always just put the slow draining shower down to the fact that there's only one outlet n it's invariably opposite the lowest-lying area of the shower tray! 

But your idea about an airvent in the waste tank sounds very plausible.


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## Spacerunner (Mar 18, 2006)

I would have thought that enough air could be displaced through the shower plughole, after all the draining water is not pressurised. The waste tank air will also be vented through unused plugholes in the wash basin and kitchen.
In the first instance I would be inclined to use a drain unblocking treatment and then get a hosepipe into the waste tank for a good back wash to make sure there is no build up of debris in the system.


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## Drew (May 30, 2005)

Hi Joe and welcome to the forum.

You have an excellent vehicle in your possession, if it is new to you I would start from scratch and clean all pipes thoroughly. There may be no blockages as such but I am willing to gamble that the pipework is full of grease etc. No matter how careful we are it is impossible to keep minor particles of grease from entering waste pipes. Your vehicle is 18 years old, how often have you or previous owners cleaned these pipes?

Have you flushed out the waste tank? if not, put a hose pipe up the spout and flush it out. You will be amazed at the amount of muck that will come out, all the muck from there has entered the tank from your waste pipes, hence the reason to clean them. 

There may be another problem i.e. a kink in a flexible pipe, but as I have said, start with the obvious and work your way through the system ensuring that all pipework is clean.


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## raynipper (Aug 4, 2008)

My Hobby shower waste is slow and the slightest build up of soap or shampoo slows it down even more.
I regularly use the flexible Swish curtain wire with a hook end and drag out any hair or other matter. 
Normally and on all our RVs there was always a roof vent from the on-board tanks. I think our Hobby has one.

Ray.


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## holeshole (Mar 20, 2010)

Don't know if it applies in your case but our 2005 Bessacarr has separate drain pipes running from the kitchen sink, bathroom sink and shower tray to the waste tank near the back of the van. Each pipe incorporates a cleanable smell-trap, equivalent to a U-bend on a domestic sink. The smell traps for the sinks have flexible pipes on the inlet (the shower tray has a short vertical length of rigid pipe) and all traps have rigid pipes from trap to tank. These rigid pipes have very little, if any, fall and so the flow rate is never going to be great.

First pic shows smell-trap in kitchen sink drain, second pic smell-trap from bathroom sink in foreground, shower tray drain behind

I found these traps after our drains began to run very slow - they weren't brilliant when we got the (second-hand) van! Cleaning the traps (and they were very gungy with hair and muck), and jetting the pipes with a garden hose, made a marginal improvement but not as much as I was anticipating. Pouring boiling water and drain cleaning chemicals down, and prodding with bits of wire, didn't seem to make much difference either.

I found the biggest improvement came after using a traditional sink plunger. I had been reluctant to use this at first for fear of splitting the flexible pipes, however they survived though I will admit I went very gingerly to start with. I was amazed at the amount of muck that the plunger brought back through the plug holes, even though I had cleaned the smell-traps and jetted the pipes immediately prior to using the plunger. Regular use of the plunger (we even carry one aboard now) is the only way we have found of keeping the drains tolerably free running.

Alan


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## Mrplodd (Mar 4, 2008)

The op clearly says that the shower drains quicker if the waste tank valve is open! So there is clearly nothing blocking the pipe (if there was then there would be no difference in the speed of drainage would there???) 

He has it spot on, it would appear that the vent pipe is NOT working as it should.

You need to investigate the top (or very near the top) of the waste tank to locate the vent pipe (it won't be very big) or possibly just an opening but that's unlikely to be blocked. It's there somewhere, but might take a while to find it. Forget about drain cleaners etc at this stage as the pipe clearly CAN drain youR shower fast enough, but CANT because the water entering the waste tank is unable to displace enough air quickly enough. 

Andy


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## Joeo's (Dec 11, 2016)

Thanks all. I've added posts but they have disappeared into cyberspace I think.
I still favour a vent problem but very tight access and one tank inside another, I think it is probably beyond my capacity to do from lying on the ground


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