--- RV Gray Water ---
The Gray Tank is the simplest of the various holding tanks in an RV. Gray Water is the waste from taking showers, washing dishes and other sink water. If you have a washing machine, its water would also go to the Gray Tank.
The Gray Tank is generally smaller than the Fresh Water tank, which is important to remember when you are Boondocking. I have a 40 foot Class 'A' and my tanks hold: Fresh = 90 gal, Gray = 55 gal, and Black = 30. If I am relying on my tanks and start with a full white tank, my combined Gray and Black Tanks will not hold all that water.
If you are heading out on a no-hookup trip, be sure to start with the Gray and Black Tanks empty. While the Gray Tank does not hold sewage, it is not a good idea to dump the Gray Tank at any place other than an approved dump station.
This is not a concern when in a campground with full hookups. I generally leave my Gray Tank valve OPEN and just let the used water flow to the sewer system as I use it. If you close this valve and forget, you will soon see water bubbling up from your shower drain. A day before I flush my Black Tank I will shut the Gray Valve and let some water accumulate in that tank to flush the sewer hose after flushing the Black Tank. If I am connected to a sewer system, the Gray Tank is OPEN. Otherwise it fills too quickly and I am asking for a flood.
The two problems you can encounter with a Gray Tank are the sensors not working or a tank leak. As the Gray Tank does not receive the same paper and other bulk waste that the Black Tank does, sensor problems can be harder to fix than a simple flushing out. The same is true about leaks. Unless you are quite the handyman, these problems are best referred to a qualified RV tech.
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