tank dump valves

Should I Leave Gray Tank Valves Open at Full Hookup Sites?

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Leaving your gray tank valve open at a full hookup site seems like a good idea, but there are several reasons that you shouldn’t do it.  Even at full hookup sites you should dump your tanks the same way you would at a dump station.  That means letting your tanks fill up close to capacity then dumping the black tank first followed by the gray tank.

Reasons to Keep Your Gray Tank Valve Closed with Full Hookups

You might be thinking, but if I leave the valve open I’ll never have to worry about over filling the tanks or going out early in the morning or late at night after someone took a long shower and filled the tank up.  That is true, but there several reasons you should keep the valve closed.

1 – It Prevents Buildup of Solids in the Gray Tank

Most RVs have 1 gray tank that connects to the shower, bathroom sink and kitchen sink.  While the shower and bathroom sinks are usually pretty free of solid items, your kitchen sink isn’t.  Every time you wash dishes all those little pieces of food make their way into the gray tank.  Once they get there the flow of water from the sink can spread out and slow down leaving all those pieces stuck to the bottom of the tank.  Once the water has all drained out those stuck pieces can dry up making them almost impossible to remove.  The best way to avoid this is to fill your tank and then dump it, creating a much higher flow with more force to clean the tank out.

2 – You Need the Gray Water to Flush Your Sewer Hose

After dumping your black tank there may be some nasty things left hanging out in your sewer hose.  Having plenty of water in your gray tank allows you to flush that out with some clean and probably soapy water.  This will help keep your sewer hose clean and free of odors.

3 – Prevent Sewer Smells Around Your Campsite

This may not always happen but leaving your gray tank valve open while you are at a full hookup site could allow sewer gas and odors to enter you camper or campsite.  This can occur in your camper if one of your drain traps dries out and no longer seals that odor in the tank.  The outside smell can occur if the campground sewer odors get pulled into your tank and exhaust out of the tank vent on the roof of your RV.

4 – Keep Sewer Flies Out of Your Tank

Another less common occurrence is sewer files in your tank.  This is more likely to happen in campgrounds with septic type sewer systems where files may be living.  By leaving your valve open you create a direct path for the files to enter your tank and make a home.

Wrap Up

Hopefully, you are convinced that keeping your gray valve closed at full hookup sites is the way to go. 

Bonus Tip:

If your gray tank fills up and you don’t have much time left on your stay, don’t drain it down more than ½ way.  Now you should still have enough gray water to flush your sewer hose before you leave.

If you are looking for more tips on using your RVs waste tanks please check out these other articles on Weekend RV Adventures about how to dump your RV’s tanks and how and when to use RV tank chemicals.

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Thanks for reading and Happy Camping