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The Practical Guide to Your RV Gray Water Tank

The Practical Guide to Your RV Gray Water Tank

Heading out on the open road in an RV can be exhilarating. Beautiful landscapes, unique destinations, and the prospect of creating special moments are all part of the RV traveling dream. However, being knowledgeable regarding your RV, including its various functions and features, can save you significant unnecessary stress. One component you shouldn’t overlook is the RV gray water tank. 

What Is an RV Gray Water Tank? 

The RV gray water tank is just as important as the fresh water tank or black water tank. Anytime you utilize a sink or shower within the RV, the dirty water collects in the gray water tank. 

showers fill your RV Gray Water Tank
Water that goes down the shower drain flows into your RV gray water tank.

This receptacle differs from the black water tank, which collects wastewater from your RV toilet

How an RV Gray Water Tank Works

Simply put, the gray water tank collects the water as it drains from the sinks and shower in your RV. This includes soapy water from washing hands and bathing, as well as small bits of food or grease from dishwashing. The tank holds this water until you can adequately drain it.

Tank Capacity

The capacity of any gray water tank is dependent upon the specific RV. You can find your tank’s capacity in the RV manual. 

The vast majority of RVs also have a gauge that depicts the gray tank’s current level. Keep a very close eye on your gray water tank gauge throughout your adventures, and always dump the tank as needed. Otherwise, you may be dealing with an untimely (and frustrating!) backup. 

How Often Do You Need to Dump Gray Water?

How often you will need to dump your gray water tank is truly dependent on how much water you use daily. Do you and your travel companions shower daily in your RV? Are you frequently washing the dishes? Do you catch yourself accidentally leaving the water running when brushing your teeth or washing your hands? 

RV Gray Water comes from doing dishes and showering
The water from doing your dishes goes into your RV gray water tank

Some RV owners may need to dump their gray water a few times a week. Others using water from outside sources (such as at a campground) may do it much less often. For this reason, it’s essential to keep a close eye on the tank’s gauge. 

How to Know When Your RV Gray Water Tank Is Full

Your RV gray water gauge will show when it’s nearing full. If it’s not working correctly, you may discover the tank is full if the shower water begins to back up while you’re bathing. Seeing gray water backflow up your shower drain might be concerning, but it usually doesn’t mean anything is wrong. Most of the time, it merely indicates that you’re overdue to drain the gray tank. 

Dumping Your Gray Water

Dumping your gray water tank is reasonably straightforward, especially after some practice. The key is to be patient, thorough, and use the correct tools. 

First, you’ll need to locate the gray water valve on the outside of your RV, which should be clearly labeled. After putting on gloves, hook your sewer hose up to the gray water valve and secure the other side of the hose to the sewer drain at a designated dumping station (never dump your gray water on the ground!). 

rv dump station

Next, check that you’ve tightly fastened both ends of the hose. Pull the valve to allow the tank to drain completely. When you can no longer hear any water moving through the hose, it’s safe to close the valve completely. 

Finally, disconnect the hoses from both the gray water valve and the sewer drain. For best results, flush the black water tank first and then the gray water tank. This will help to dislodge and remove any solid waste in the sewer hose. It’s also smart to rinse the gray water tank after dumping, using either a flush valve or a tank rinser.  

Cleaning Your Gray Water Tank

To keep a well-maintained gray water tank, cleaning it periodically is imperative. Don’t wait for your gray water tank to smell before giving it a good clean! Instead, schedule time to clean the tanks and try to do so when you’re driving a long distance. 

To clean the tank, add a half-cup of an RV-specific cleaning agent (such as Calgon) to a half-full gray water tank, along with a half-cup of dish or laundry detergent. If you don’t have Calgon, try baking soda, laundry detergent, or dish detergent. 

Arm & Hammer Baking Soda - 64 oz
  • Arm & Hammer baking soda is pure, safe and natural
  • For scratchless cleaning in the kitchen and bathroom
  • Absorbs and eliminates odors on contact

After adding the cleaning agent, hit the road! The sloshing movement of water in the tank will help break down buildup. The gray water and cleaning solution should then sit in the tank for another 24 – 48 hours before draining. 

Odor Troubleshooting and Prevention Tips

Preventing unwanted odors within your RV gray water tank is optimal. To do so, simply clean your gray water tank regularly, and avoid adding unnecessary particles to the gray water tank.

When washing dishes, scrape any food particles off the dish and into the trash rather than letting the particles go down the sink drain

RV Holding Tank Odor Control 😵 - Air Admittance Valves

Although it may seem like a strange tip, reducing your soap usage can further prevent build-up on the tank. Soap surprisingly aids in pesky odors. If you can take advantage of wash facilities outside your RV, this can reduce the need to clean and drain your RV’s gray water tank as often. 

If you begin to smell an odor coming from your gray water tank, you can use any number of products specifically designed to eliminate odor. Most of these products also work to remove buildup. It’s imperative to follow the directions on these products for good results.

Happy Campers Organic Holding Tank Treatment works well at eliminating odors.

Happy Campers RV Holding Tank Deodorizer Treatment...
  • ODOR FREE: Eliminates odors in the RV holding tank. Absolutely no...
  • Septic tank friendly
  • EFFECTIVE: In extreme hot & cold temperatures ( over 100 Deg)

Caring for Your RV Gray Water Tank Is Crucial

Understanding and adequately caring for the gray water tank in your RV is crucial. Before beginning your first RV adventure, note the tank’s capacity. Learn how to dump and clean the tank properly and what to do if unpleasant odors arise.

With this knowledge, you’ll be better prepared to tackle any gray water tank maintenance or hiccups along the way. 

rv sewer hose to dump gray water tank and black water tank

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About Mortons on the Move

Tom & Caitlin Morton of Mortons on the Move gave up the stationary life for one where they are constantly on the move. They are full-time travelers, television hosts, and digital media producers.
They left their jobs, sold their house and possessions, and hit the road in September 2015 in their full-time “home on wheels”. Since then they have traveled the US, Canada, and even internationally by RV.
Now, they are Discovery Channel & PBS TV Co-stars of “Go North” on Amazon Prime Video, co-founders and instructors of RV Masterclass, and contributing authors for and an Arizona travel guide.

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Not So Free

Monday 22nd of February 2021

I like the Geo Method, You can google it. It basically uses water softener and bleach in both tanks as well as detergent in the black tank. I've used it in the last to RVs I've had and never had a clog problem. It even *kinda* keeps the sensors working.

Mortons on the Move

Tuesday 23rd of February 2021

Thanks for the tip!

Thurman Whiteley

Monday 22nd of February 2021

One way that I have discovered and use all the time is Paper plates ect. It reduces my water use and saves my Grey water tank from filling to quickly while boondooking.

Mortons on the Move

Monday 22nd of February 2021

Doing dishes less often will definitely help! We use a touch faucet when we do dishes, so the water isn't running constantly. Other people wash dishes in a separate basin so they can toss the dishwater outside; however, this is only recommended if you're using biodegradable soap.