Slow draining from waste tank

[Tinalo]

We have had a Timberland Destiny for seven years or so. When using water for washing or washing up the water drains painfully slowly. Sometimes for no apparent reason the water will drain from the bathroom perfectly. The sensor will beep 100% full when it can’t possibly be so. When opening the waste tank tap the water only drains at a dribble. Over the last few years we have tried everything we could think of including tips from the internet. That would include unblocker granules, using a pressure water both up and down. Any suggestions would be gratefully received. My husband couldn’t get down and lie on the ground under the van, but I could try. It would seem perhaps that the waste tank could be full of gunk but we have put so much stuff down and it hasn’t made any difference.

[Billggski]

Last resort?

 

https://tinyurl.com/y3t6pp89

 

 

[Derek Uzzell]

Tina

 

1: When using water for washing or washing up the water drains painfully slowly. Sometimes for no apparent reason the water will drain from the bathroom perfectly.

 

Motorhome water outlets (‘plug holes’ in the kitchen sink, wash basin and shower tray) are seldom vented, so water tends to ‘bottle neck’ as it drains. Water pipework/hoses leading from the outlets to the waste-water tank are often sinuous and lack a continuous outlet-to-tank ‘fall’. Motorhome water drainage can also be very sensitive to the vehicle’s stance when parked, where a slight slope (not necessarily in a logical direction) can radically improve (or impair) how well an outlet drains. Unfortunately, if the pipework/hoses have no internal blockages, there’s not a lot can easily be done to address this issue.

 

2: The sensor will beep 100% full when it can’t possibly be so.

 

Waste-water tank sensors live in a hostile environment and ‘crud’ in the tank can cause the sensor(s) to false read. Attempting to correct this will require access to the sensor(s) to be gained for cleaning, and this may not be easy.

 

3: When opening the waste tank tap the water only drains at a dribble.

 

It’s possible (though unlikely) that the waste-water tank is unvented and this is slowing drainage. Much more probable is that there’s a blockage in the pipe/hose running from the tank to the drain-tap and/or the tap itself is the culprit - and UK-built motorhomes tend to have a smallish-diameter pipe/hose/tap which also doesn’t help. Try removing the tap and see if the waste-water tank then drains freely. If it does you’ll know that the tap is to blame: if it doesn’t, there’s almost certainly a blockage in the pipe/hose that you should be able to clear.

 

I suggest you be VERY careful if you choose to use anything like the Screwfix ‘corkscrew’ tool. This is intended for domestic plastic pipework not the more fragile narrow-bore flexible hose often installed in motorhomes. Similarly if using a more traditional sink/bath unblocker (example here)

 

https://www.screwfix.com/p/sink-bath-unblocker/13894

 

[paulmold]

We always carry a small sink plunger, available from Home Bargains. Also the drain tap gets clogged despite trying not to let even a grain of rice go down the sink. Could you remove the drain tap to make sure the blockage isn't there.

[Barry38]

I have had this problem in my motorhome. I found that over time and due to the constant motion of the vehicle, waste water in the tank causes any 'fat' content to form balls of crud which lodge in the outlet pipe when draining - especially if it is a fairly small outlet. I simply used a piece of wire with hook on the end - opened the tap fully and easily "fished" out the offending blockage whilst draining down. If your tap is angled (mine is straight) it may be necessary to remove the tap from the pipe end.

Very simple remedy - works every time!

[Alanb]

Barry38 - 2019-06-06 11:14 PM

 

I have had this problem in my motorhome. I found that over time and due to the constant motion of the vehicle, waste water in the tank causes any 'fat' content to form balls of crud which lodge in the outlet pipe when draining - especially if it is a fairly small outlet. I simply used a piece of wire with hook on the end - opened the tap fully and easily "fished" out the offending blockage whilst draining down. If your tap is angled (mine is straight) it may be necessary to remove the tap from the pipe end.

Very simple remedy - works every time!

 

I am sorry but a large problem with public sewers is "fat bergs". Where does the writer expect his "balls of crud" to end up? Does he not use kitchen paper towels to remove excess fat from his pots and pans, before washing up?

 

I might add that we have never suffered from waste outlet blockages except in rented vehicles. In these instances the culprits were congealed grins of rice, and coffee grounds, neither of which we use.

 

Alan

[Derek Uzzell]

Barry did put ‘fat’ in quotes and, even if actual fat is removed from pots and pans prior to washing up, soap/shampoo/shower-gel residue will find its way into the waste-water pipework and tank.

 

As I said above, the pipework of many motorhomes is inadequately designed for fast drainage from plug-hole to waste-water tank, and drainage from the tank itself (particularly on UK-built conversions) is often via a narrow diameter pipe and a dinky little water-butt-type tap.

 

Consequently ’slime’ can build up in the pipework and tank, making plug-hole drainage speed that was slow when the motorhome was new even more lethargic as time passes. And, when the waste-water tank can’t drain rapidly, there’s no ‘flushing’ action to help muck discharge and horrid smells will find their way up the pipework and out of the plug-holes.

 

(I note that Barry owns a 2009 Autocruise Rhythm - I rest my case ;-) )

[witzend]

I reguarly when filling with water put the hose in the sinks and shower drains and with a piece of rag held around the end turn the tap on to flush the pipe work and also back up the outside drain pipe plenty of bleach and only emptying after a drive with a sink plug out seems to keep our pipes free

[flicka]

A friend had this problem with slow draining from waste outlet, but sink drained normally.

Chatting to him, he always replaces all sink plugs as he was getting waste tank smells back into his van.

We tried a couple of bottles of cheap Cola & 2 kettles of hot water, drove around for a few minutes & tried the waste outlet.

There was no improvement, even though there was no sign of debris when a wire was pushed up the waste outlet pipe.

Then a "light bulb" moment, he had as usual, replaced all the sink plugs. They were effectively creating a vacuum. Removed sink & shower plugs & waste water was able to flow properly.

 

 

[TeePee]

I had this problem, tried everything, in the end I had to drop the waste tank and clean it out by hand through the hole in the top of the tank. I now try to avoid getting greasy water in the waste tank.