What Is Grey Water In An RV?

A Quick Intro To RV Plumbing

To better explain what RV grey water is, a quick explanation of how the pipes work and where everything goes is going to be really helpful.

You might think that since campers need to be simple that everything just goes to the same place. But there are always at least two different holding tanks, commonly known as black and grey tanks, in an RV.

Basically, all of the faucets in a camper, the kitchen sink, bathroom sink, and shower, run into what’s called the grey tank. And the toilet, or toilets, depending on how big your RV is, is directly connected to the black tank.

Some travel trailers and 5th-wheels will even have a second grey tank often referred to as a galley tank. This tank is normally connected directly to the kitchen sink drain.

See Also: How To Maintain RV Holding Tanks To Prevent Clogs & Odors

I’ve heard stories of RVers who had no idea that their camper had a second grey tank. One day they just couldn’t get the dishwater to drain out of the kitchen sink. After further inspection, they discovered there was a second sewer outlet on the front of their travel trailer.

There was a small second tank sitting directly under where the sink is that had never been drained.

I recommend doing a thorough inspection of the outside of your RV when you first get it to make sure you won’t be surprised later by another waste water outlet.

To go further into the topic of RV plumbing there is also the fresh water tank that feeds into the RV water pump that supplies all of the water to the taps, toilet, and shower.

But this article is going to mostly focus on RV grey water so I won’t go into that side of the RV water system.


What Is Grey Water In An RV?

Grey water in an RV is all of the waste water from everything but the toilet.

It’s what’s coming from the kitchen sink, the bathroom sink, and the bathtub or shower drain.

RV grey water can contain anything from food particles to the soap you use in the shower or on your hands when you wash them.

It’s normally very smelly and a milky white color when coming directly out of the tank.

See Also: How To Clean/Sanitize RV Water System And Holding Tanks


grey water being dumped from an rv grey tank
RV grey water is normally almost clear and not very dirty but still pretty smelly.

What Happens When The Grey Water Tank Is Full?

Even if you camp with your RV connected to a sewer at all times you’ve maybe had your grey water tank get overfilled from time to time.

What normally happens is the lowest drain starts to regurgitate grey water first. The lowest drain is pretty much always the shower/bathtub.

I’ve walked into the bathroom of our motorhome a few times only to discover some smelly standing water in the tub. It pretty much always smell sulfuric and it’s very noticeable.

See Also: How To Find Nearby RV Dump Stations & Fresh Water Fill-Up


Can I Dump RV Grey Water On The Ground?

This question is a lot more complicated than some might think. If you do a quick Google search on the topic you will find articles that just say yes, and others that say definitely no.

So who is right? And what is considered proper etiquette when camping?

After reading a ton of different articles on the subject it seems like most of the campers who are saying yes are relying on the fact that the Bureau of Land Management (BLM) doesn’t have a specific policy against dumping grey water, just black water which is classified as sewage.

They don’t have a policy against it because there are more than just RV campers out there. Tent and van campers don’t normally have a grey water tank. They just dispose of their wash water by dumping it on the ground and that seems to be ok for the most part.

The main difference between them and RVers is the amount of grey water being created. Tent campers normally aren’t able to take full showers like RVers can and they aren’t packing around nearly as much freshwater.

Many RV grey tanks hold at least 35 gallons which is a lot of water to be dumping all at once.

See Also: Best RV Portable Waste Tanks For Black & Grey Water

There’s also one more very specific rule many of these articles aren’t mentioning. In some popular camping states like Arizona, there is a specific law that states that any waste water that contains any amount of food is instantly considered sewage since it can attract animals and has decomposing organic matter in it.

This small law automatically makes it technically illegal for most RVs to dump their grey water because most have just one grey tank.

This is where having a separate galley tank that’s connected directly to the kitchen sink could come in handy.

Another instance where it’s illegal to dump the grey tank on the ground is if there’s a no dumping policy in the specific camping area. This is a sign we see a lot as boondockers, even on BLM land.

blm campground sign that states there is no rv grey water dumping allowed
Even though it’s BLM land there is no RV grey water dumping allowed in this area.

It’s very rare to drive into a free camping area that doesn’t have a no dumping sign of some kind.

Grey water may mostly just be water and soap but it’s still really nasty. You’ve got the dirt and oils from people washing their bodies and whatever was on their hands when they washed them. Not to mention all of the grease and food from dishes.

Anytime someone dumps their grey tank when camping even in the middle of the desert the smell lingers for quite a while and it’s not fun to camp in a spot where someone has done this.

See Also: What To Do When An RV Waste Tank (Black/Grey) Won’t Drain

So, the short answer to is it ok to dump RV grey water on the ground?

No.

After some research, the only time it’s ok for an RVer to dump the grey tank on the ground is if you are camping in an area that doesn’t have any no dumping signs posted, you are using biodegradable soap that is not petroleum based, and you have a separate grey tank for your kitchen sink.

In this small instance, you technically can dump the grey tank that is only being filled by the shower and bathroom sink on the ground legally.

As far as camping etiquette goes many campers look down on dumping the RV grey tank on the ground and it isn’t considered good manners.

Have any more questions about RV grey water? Leave a comment below.

by Jenni
Jenni grew up in a small town in Idaho. With a family that loves camping, she has been towing trailers since a very young age.

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