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How much Water does a Gray Tank Hold? (RV FAQs)

How much Water does a Gray Tank Hold? (RV FAQs)

Owning and operating an RV comes with a lot of new systems you must learn about. One of those systems is the water system that gives you running water, allows your toilet and shower to work (if you have them), and gives wastewater a place to go until you can remove it. Gray tanks are included in that crucial system. You may be curious about the capacity of these tanks.

So, just how much water does a gray tank hold?

A smaller RV gray tank holds anywhere from 25 to 45 gallons, while the largest RVs will have gray tanks holding 40 to 65 gallons. How much gray water an RV’s holding tank can carry will really depend on the size and type of RV that you have. 

Together, we’ll explore in-depth the capacities of gray water tanks in RVs and what gray tanks are. We’ll get you up-to-speed on everything you need to know to be confident in owning an RV.

RV Gray Water Tank Capacities

Finding the typical tank capacity is difficult since the size of an RV holding tank frequently correlates with the size of the RV. For instance, a Class A motorhome has a larger gray water tank than that of a Class B campervan.

A class A RV typically has a gray water tank with a capacity of 40 to 65 gallons, a fifth-wheel would have a gray water tank with a capacity of about 95 gallons, and the majority of travel trailers have a gray water tank with a capacity of 25 to 45 gallons.

What is a gray water tank?

RV gray water tanks are the holding containers into which the indoor shower and sink of your RV drain. Gray water in an RV is any used water that is not toilet water. As a result, water from the indoor shower, bathroom sink, and kitchen sink is collected in this specific tank.

The wastewater from tasks like washing dishes in your sink in the kitchen area or washing your hands in the bathroom sink goes straight into this tank.

Larger RVs frequently have dishwashers and/or washing machines, and these appliances typically empty straight into the gray tanks, which can quickly fill the entire tank.

So, many washing machines for RVs come with instructions that they should be used only when attached to the proper hookups at a campsite or RV park, and the valve is open to avoid the RV’s gray water tank from overfilling.

Other Types of Water Tanks in an RV

The gray tank is not the only water tank an RV has. Since this tank is for the water that comes from your shower and sinks after use, the other water in your RV from your toilet or to provide you with fresh drinking water and water to shower in needs a place to be held as well.

Fresh Water Tank

Usually, the fresh water tank is the biggest of the three. Most of the time, it is manufactured with corrosion-resistant metal, but some models might have plastics like polyethylene.

Use an approved potable water hose to fill the fresh water tank on your RV. To prevent cross-contamination with wastewater, use this white hose. Therefore, the freshwater tank should only be connected to the potable water hose, not the gray or black tanks.

Black Water Tank

Wastewater is discharged from the toilet drain into the black water tank. Never try to empty the black water tank of your RV at an unapproved disposal site.

Since most places have laws that require RV operators to dump their black water in specified places, this practice is not only poor RV etiquette but could also result in a hefty fine.

Additionally, until the black water tank is nearly full, you should leave the drain valve closed. The general idea is to give the solids enough time to dissolve so that the water can be drained more easily when the valve is finally opened.

How regularly should you empty a gray tank?

How often you should empty your gray tank depends greatly on a few different factors. Depending on the size of your RV, your gray tank may be able to hold a great amount of water before you need to pay a visit to the dumping station.

If you travel with others in your RV, you will inevitably be using more water each day. This will cause you to have to empty the tanks every few days or so depending on just how much water each passenger uses. 

Alternatively, if you are traveling alone, you will be using up fewer resources and will therefore need to empty the water tanks less often. Sometimes, you may even be able to go a few weeks without visiting the dumping station to unload your gray and black water. 

Many modern RVs also come built with a sensor that will alert you when your tanks are filling up.

How do you properly clean a gray tank?

Cleaning your gray tank in your RV can be relatively easy. One way to help keep it clean from the start is to reduce the number of food bits you wash down your kitchen sink. Rinsing your dishes with a lot of food waste on them isn’t good for the system. You can also buy gray tank cleaning specific products.

Take the time to remove all food residue from your plates and bowls before rinsing them in your sink. This will help ensure your gray water tank stays cleaner. 

If your gray water tank is giving off an unpleasant odor, you can try a few simple things. Before setting out on a day of travel, buy a cup of dishwasher detergent and pour it into your kitchen sink to help with the strong smell.

The detergent mixture will be able to splash and mix around in the gray tank to help remove any strong odors. Any debris that is able to be removed from the interior of the tank will be flushed away once you clear your gray water tank once more.


Closing Thoughts

Having an RV can be overwhelming with all of the intricate systems you need to learn how to operate and maintain. The RV gray water tank is a relatively easy one to learn about and maintain so your RV can continue to run smoothly for years to come!


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