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Grey water tank won't drain completely

epennal
Explorer
Explorer
New RVer here. My Grey water tank will only empty down to the 2/3rd level. Not completely clogged, obviously, but why would it stop draining at that point? I don't think it's a sensor issue because it does seem to stop short of completely emptying, plus it doesn't take long to fill back up to the full mark.
20 REPLIES 20

Goldencrazy
Explorer
Explorer
We all suspect sensors because we have all been there and grey tanks rarely clog. That said something could be caught and not letting it drain so be a bit more scientific with "seems like fills faster". Keep track as best you can over the next use age period.

wa8yxm
Explorer II
Explorer II
The problem is not the tank draining it is that the sensors always show 2/3.

And that is normal.. Alas there is no effective cure for it other than a different type of sensor

HORST miracle probes claim to work better.

See Level sensors (not probes) do work better.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times

rgatijnet1
Explorer III
Explorer III
When the grey tank valve is open, have someone dump a gallon of water in to the kitchen sink. If the water quickly flows out of the drain, then that will show that there is not something blocking the drain and that the most likely cause is a bad sensor.

2edgesword
Explorer
Explorer
I would also think that it is much more likely this is a sensor issue versus anything that would allow 2/3rd to drain and somehow block the last 1/3rd.

Effy
Explorer
Explorer
Are you sure it's not the sensor instead of the tank actually draining? Try flushing the tank a few times (Fill completely and then empty). This might clean the sensors. All kinds of things can stick to the probes and cause a mis-reading. Frankly the stock sensors aren't really very reliable. One of the reasons I installed tank flush systems on both black and grey.
2013 ACE 29.2