RV Fresh Water

What is RV Fresh Water?

RV fresh water is fresh, potable water that is either pumped from an outside source or stored in the fresh water tank. The fresh water systems pull clean water through the RV plumbing to supply water to the toilet, sinks, shower and washing machine. 

Understanding RV Fresh Water

Most motorhomes have three holding tanks for water: (1) the fresh water tank, (2) the gray water tank, and (3) the black water tank:

• The RV fresh water tank holds  clean water for use in the shower, sink, dishwasher or for other fresh water uses; 
• The RV grey water tank holds the dirty water from the RV shower, sink and dishwasher; 
• The RV black water tank holds human waste and other content that flush down the toilet.

The RV plumbing systems pull water from the fresh water source to be used in water-using appliances. It is then drained into either the gray water or black water tank. There it will be stored until ready to be emptied into a designated sewage dump station.

There are two ways to utilize fresh water from an RV: (1) directly from a fresh water source such as a campsite water filling station, or (2) from water stored in your tank. 

Using Water from a Fresh Water Source

At campgrounds with full or partial hookups, a fresh water or potable water source will be located on at the campsite. Simply connect one end of the water hose from the campsite spigot to the RV’s local water port. The fresh water hose should be a food grade hose – not a rubber hose. Ensure the hose is connected to the local water source port to bypass the tank and route water directly to the plumbing system.

If connecting to a fresh water source, it’s a good idea to have a water pressure reducer valve at the source. This way, the water flows slowly and smoothly to the motorhome and you don’t risk blowing out the water lines. 

Once connected to the fresh water source, the next step is to turn on a faucet in the RV. It may take a few minutes for water to flow through the plumbing system before a steady stream of water will flow. A little bit of sputtering for the first few minutes is normal while air clears from the plumbing. 

Using water from the RV Fresh Water tank

If using water stored in the RV fresh water tank, the process is relatively the same. After parking the RV in a stationary place, turn on the RV water pump. The pump switch is usually located on the instrument panel that reads “tank fill level” or directly on the fresh water tank itself. Simply turn the water on. Again, some sputtering while air clears from the plumbing is normal.

Filling the RV Fresh Water tank

When boondocking or staying at sites without a water hookup, the fresh water tank needs to be filled before setting out. Using the food grade fresh water hose, connect the RV to a fresh water source. This can be a spigot from your home or a local source dedicated to filling RV fresh water tanks.

Ensure the handle on the RV tank is set to ‘fill tank’ or the hose is connected to the tank fill port. The water level in the fresh water tank can be read on an instrument panel, usually located in the RV coach.

Emptying the RV Fresh Water Tank

When the camping trip is over, it is important to empty the RV clean water tank in addition to the black and gray holding tanks. Leaving water in the tank in cold conditions can cause pipes to freeze, which can be costly to repair. If water is left in the tank in warm conditions, it creates a breeding ground for bacteria, which can cause illnesses at worst and a bad taste at best.

To empty the RV fresh water tank, simply turn off the water heater, wait for it to cool, then open all valves for water sources by turning sinks and showers to the on position. Keep the valves open until all water has cleared from the tank and no more water comes out of the faucets. This will move all water into the gray water tank, where it can then be emptied into a designated sanitary dump.

Sanitizing the Fresh Water Tank

Once the fresh water tank is empty, sanitizing it is relatively straightforward. First, measure out ¼ cup of bleach for every 16 gallons the tank holds.^[1]Camping World Dilute the bleach in at least one gallon of water and pour the mixture into the fresh water holding tank with a funnel. 

Then, fill the tank completely full with clean water and turn on all water appliances. This will ensure that the bleached water gets through all pipes and waterways your fresh water will touch. Allow the bleach-water mixture to flow through the pipes freely from the faucets for a few minutes. Then, turn the water off and let the system rest for at least eight hours to ensure the bleach has enough time to kill off any bacteria that may be present.

Finally, drain the fresh water tank as described above and flush the entire system several times until the smell of bleach is gone.

Related RV Terms

For related RV terminology, please reference the RV definitions below:

• Black Water: Waste collected from an RV toilet, which is stored in the black water tank.
• Gray Water: Water collected from the drains of non-toilet RV appliances such as the sink and shower which is drained into the gray water tank.
• Full Hookup: A campsite with amenities to connect an RV to fresh water, electricity and wastewater dumps.
• Shore Power: The connection of electricity to the RV from an outside power source like a campsite’s electrical pedestal.