If you’re new to RVing, one of the most common questions you’ll have is about your RV’s water system. Many first time RV owners notice two different water connections on the outside of their camper or motorhome and immediately wonder: Which one do I use?
The answer depends on where you’re camping.
Most RVs are equipped with both a fresh water holding tank and a city water connection, giving you flexibility whether you’re camping with full hookups or traveling somewhere without access to water.
In this guide, we’ll explain the difference between these two systems, when to use each one, how to fill your fresh water tank, and a few simple tips that can help you avoid common mistakes.
Understanding Your RV’s Fresh Water System
Your RV’s fresh water system is designed to provide clean water for everyday tasks like:
- Washing your hands
- Taking a shower
- Flushing the toilet
- Washing dishes
- Cooking
- Drinking (if your water source is safe)
Most RVs have two ways to supply this water:
- The fresh water holding tank
- The city water connection
While both provide water to your RV’s plumbing, they work differently and are used in different situations.
What Is the Fresh Water Holding Tank?
The fresh water holding tank is exactly what it sounds like: a storage tank built into your RV that holds fresh, clean water.
Instead of relying on a campground water hookup, you’re carrying your own water supply wherever you travel.
This is especially useful when:
- Traveling between destinations
- Overnighting at rest stops
- Camping without hookups
- Boondocking or dry camping
- Making roadside stops
Once the tank is filled, your RV’s water pump supplies water throughout the coach whenever you turn on a faucet.
How to Fill the Fresh Water Tank
On many RVs, you’ll find a dedicated fresh water fill on the outside of the unit.
Some models have this connection directly on the sidewall, while others place it inside what’s commonly called a water station or water compartment.
Although different manufacturers may arrange these connections differently, the process is generally the same.
Step 1: Connect Your Hose
Insert your fresh water hose into the fresh water fill opening.
Many experienced RV owners like using a hose with the threaded end removed because it slides farther into the fill opening, helping direct the water into the tank.
Step 2: Turn the Water on Slowly
One of the biggest beginner mistakes is turning the faucet on full blast. Doing so can cause water to splash back out of the fill opening, leaving you wetter than your RV.
Instead, turn the water on gradually and allow the tank to fill at a steady pace.
Step 3: Monitor the Water Level
While the tank is filling, you have two ways to know when it’s getting full:
- Check your RV’s monitor panel inside.
- Listen for changes in the sound of the tank filling.
Eventually, water will begin coming back out of the fill opening or vent.
When that happens, your fresh water tank is full.
What Is a City Water Connection?
The city water connection allows your RV to receive a constant supply of water directly from a campground faucet.
Instead of using water stored in your fresh water tank, the campground supplies pressurized water through your hose and into your RV’s plumbing.
This means:
- You won’t need to refill your fresh water tank.
- You typically won’t need to use your water pump.
- You’ll have continuous water as long as you’re connected.
If you’re staying at a campground with full hookups, this is usually the easiest option.
How to Connect City Water
Using your city water connection is straightforward.
Connect Your Drinking Water Hose
Attach one end of your fresh water hose to the campground’s water faucet.
Connect the other end to the city water inlet on your RV.
Turn the Water on Slowly
Again, avoid opening the campground faucet all at once.
If you’ve accidentally left a faucet open inside the RV, a sudden rush of water can surprise you with an unexpected splash.
Turning the water on gradually gives you time to make sure everything is working properly.
Remove Air from the Plumbing
After connecting, head inside your RV.
Turn on the nearest faucet slowly and let it run for a minute or two.
At first, you may hear:
- Gurgling
- Sputtering
- Burping sounds
This is completely normal.
It’s simply the trapped air working its way out of the plumbing lines before a steady stream of water begins flowing.
Fresh Water Tank vs. City Water: Which Should You Use?
The right choice depends on how you’re camping.
Use the Fresh Water Tank When:
- You’re traveling between campgrounds.
- You’re boondocking.
- You’re camping without hookups.
- You’re stopping overnight.
- You’re preparing for emergencies.
Use City Water When:
- You’re staying at a campground with water hookups.
- You want unlimited running water.
- You don’t want to rely on your water pump.
- You’re staying in one location for several days.
Many RV owners use both throughout the same trip.
Why You Should Still Fill Your Fresh Water Tank Before Leaving Home
Even if you’ve reserved a campsite with full hookups, it’s smart to travel with at least some water in your fresh water tank. You never know what might happen on the road.
For example:
- Traffic delays
- Unexpected overnight stops
- Rest area breaks
- Mechanical issues
- Campground water outages
- Late arrivals after campground offices close
Having water onboard means you can still:
- Wash your hands
- Flush the toilet
- Prepare meals
- Drink water (if properly sanitized)
- Clean up after pets or children
A partially filled fresh water tank provides peace of mind during travel.
Different RVs May Look Different
One thing that confuses many new RV owners is that not every RV is set up exactly the same.
Depending on the manufacturer and floorplan, your RV may have:
- Separate fresh water and city water connections
- A centralized water station
- A utility compartment with multiple valves
- A single inlet with valve selections for different functions
Even though the layout may vary, nearly every RV follows the same basic principles:
- One system fills your onboard fresh water tank.
- One system supplies pressurized water directly from an outside source.
If you’re unsure which connection is which, your owner’s manual or dealership walkthrough can help identify them.
Common Beginner Mistakes
Most new RV owners make one or more of these mistakes at some point:
- Filling the wrong connection.
- Turning the water on too quickly.
- Forgetting a faucet was left open.
- Assuming every campground has reliable water service.
- Traveling with an empty fresh water tank.
Fortunately, all of these are easy to avoid once you understand how your RV’s water system works.
Final Thoughts
Remember that your fresh water tank gives you independence while traveling or camping without hookups, while the city water connection provides a continuous water supply when you’re staying at a campground. Knowing when to use each system ensures you’ll always have access to water wherever your travels take you.
Before every trip, take a few minutes to fill at least part of your fresh water tank, even if you’re heading to a full hookup campground. It’s a simple habit that can make a big difference if your plans change along the way.
