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How To Drain a Grey Water Tank on an RV

Most RVs have three tanks to capture and hold different kinds of water while you are out traveling. The fresh water tank holds water for drinking, showering, and cooking. The black water tank holds the results of toilet use. The grey water tank is the second least gross tank to empty, and has the drained water from your shower, sink and other drains.

You’ll need to drain the grey water tank every few days, especially while traveling with a few people. While the grey tank is generally pretty easy to empty, you might want a bit of instructions, especially when doing it for the first time.

Grey water tanks can be emptied in a couple of ways. You’ll generally use a hose at an RV park or a public station. You can also empty your grey water tank at a residence. Read below for more details.

How to hook up the hose to drain a grey water tank on an RV – at a park

Here is the first part – while you don’t technically need a hose with most RV grey water tanks, it’s far easier and less messy to use a hose.

If you don’t have a hose for the purpose, get one. Store it in the external compartments on your RV if you have them.

  1. Locate the water tanks on your RV before starting, if you do not already know where they are.
  2. If you aren’t already at one, you might want to look up RV park locations or waste water locations on the Internet or in a phone book.
  3. Go to an RV park or a place with sewer receptacles for the purpose. Park your RV so your tanks are close to the receptacles. The receptacles are more often than not in a concrete slab besides parking spaces on the lot. 
  4. Put on disposable gloves, preferably latex or whatever works for you.
  5. Hook up the end of the gray water waste hose to the gray water sewer receptacle at the RV park. The receptacle is usually on the ground and the gray water sewer receptacle is generally gray or labeled in some way. Pushing the hose into the sewer line shouldn’t take much effort.
  6. Locate the gray water tank opening on the bottom of your RV.
  7. In order to prevent from making a mess or spilling too much, hold the hose under the gray water tank opening as you take the safety cap off the tank.
  8. Connect the hose to the gray water tank.
  9. Open the valve for the gray water tank. Generally, this is a stem sticking out of the tank that can be pulled. While it’s called a valve, it doesn’t look like the circular water valve on your plumbing in most cases.
  10. Once it finishes draining, put the caps back on both the gray water tank and the sewer receptacle.
  11. Close the valve on your grey water tank. This is generally done by pushing the valve back in.
  12. Put away your hose in its compartment. You might want to consider taking a look at it and rinsing it with fresh water prior to storing.
  13. Throw away those gloves!

Note that these instructions are exclusively for only emptying your grey water tank. It’s generally recommended to empty the black water tank first then use the same hose to empty the grey. 

Why? The grey water will flush the waste out of the hose. Definitely don’t do the black water last!

Can I drain the grey water tank at a place besides an RV park?

Some states consider gray water to be similar to fresh water. Contact our local transportation authorities in your current place to see what they say. There may be a fine if you are caught illegally dumping gray water in a place where it’s not allowed.

The process will be quite similar and we would still strongly suggest using the hose so you don’t get wet. 

You can extend the hose away from the RV and put it on the ground, then let it empty. The safest place is probably the ground, as are you unlikely to be able to pull your RV directly up to a body of water for the purpose of draining. The ground can also filter out the grey water.

Since the end of your hose isn’t attached to anything, you might want to find a 

We still recommend wearing gloves and throwing them away immediately after.

How can I make it easier?

It’s ok to let you grey water tank get a bit more full than your black water tank. Grey water doesn’t tend to carry the same smell. Letting it get more full can make the grey water come out faster.

If you don’t already have a hose for the purpose, certainly get one. Buy disposable gloves in bulk, too, so you don’t run out. The last thing you want is a full black or gray water tank and need to empty while on a trip using your bare hands.


Draining your grey water tank is made easier by prearranged facilities like your RV park. While it’s possible to drain the tank at a place without a sewer, you should contact local authorities before getting caught doing something potentially harmful.

The most important parts are to ensure you have a hose stored somewhere outside the RV, gloves, and a little bit of time. Empty your tanks when needed and you won’t have to worry about having them go beyond their capacity.

Go enjoy your RV trip and head on back when you need some more advice.

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