Your RV Water System Explained
(Camp Addict does NOT accept payment from any company to review or endorse their products.)
So you have an RV. You know there's some way that water runs to your sink, toilet and shower.
But how, exactly?
An RV water system can be confusing at first.
There's a difference between using a city water connection (hose connected to your camper) and using your RV water pump to circulate H2O stored in your fresh water tank.
If you aren't familiar with how an RV fresh water system works, you've come to the right place.
Here you will learn how water gets into your RV, where to find water if you are not at a campsite with a fresh water supply, and maybe even find out a thing or two about your fresh water pump.
Need to replace your water pump? Use the button below to open up the reviews and find the right type for your rig.
How To Get Running Water In Your RV
Most RVs have two options to get water coming through your RV plumbing system:
- Attaching a hose to your RV from the outside ('city water connection')
- Using the RV's pump to use water stored in your fresh water tank
City Water vs. Fresh Water Tank
Using City Water
One way to get water flowing through your faucets is to attach an RV water hose (different from a regular garden hose) from a spigot to the water inlet on the outside of your rig.
This is what is called using 'city water'.
With the city water method, you don't have to fill your holding tank or 'fresh water tank'.
You also don't need to use your water pump.
City water bypasses the fresh water holding tank completely.
When using city water, you can keep the outside water spigot on all the time.
This way, the water pressure from the spigot pushes the water through your RV water system.
So, no need to use your built-in water pump.
Turning the water off at the spigot (outside) when you aren't home is a good option to eliminate disaster if your RV plumbing system pipes spring a leak.
Of course, using city water only works if there's a nearby spigot you can use.
If you go to an RV park and pay for 'full hook-ups', you will have a dedicated spigot to use.
When using city water, it's a VERY good idea to get a water pressure regulator to attach to your RV water hose.
Some RV parks have pressure that is too high for RV plumbing systems.
In such cases, it can bust the water pipes inside your rig, or cause leaks at plumbing fittings.
Having an RV water pressure regulator will help prevent this disaster.
Obviously, you can't use city water if you are out in the woods (boondocking) or if you are camping without water hookups.
If that's where you are going, you need to fill your freshwater tank before you get there.
Water Pressure Regulator
A water pressure regulator is essential to use when you are connected to any outside water supply.
Water pressures from town to city to town will vary.
Some have very high water pressure which can damage your existing water lines, causing a leak.
A leak will cause water damage, which is the #1 worst thing that can happen to your RV.
ALWAYS have one of these in place when connected to an external water supply.
Using Your RV Fresh Water Holding Tank
Pretty much any RV with a sink, faucet or shower in it also has a freshwater holding tank.
This is how you get water when you are boondocking.
You may either fill your fresh water tank at home before you hit the road, or you can fill it just before you arrive at your campsite.
Also, some campgrounds will have a designated area where you can fill your fresh water tank before settling into your campsite.
If your rig is already close to its GVWR (gross vehicle weight rating), it's best to not drive with your fresh water tank full the entire way, depending on how far you have to go.
Driving with your tank full also affects your gas mileage to a certain degree, depending on the capacity of your fresh water tank.
Keep in mind that each gallon of water weighs approximately 8.3 lbs.
You do the math for your water tank (capacity in gallons x 8.3).
Of course, driving with a full fresh water tank also depends on where you can or cannot get water.
Sometimes the nearest water source is nowhere close to where you are camping.
In this case you have no choice but to fill your fresh water tank before arriving at your final destination.
To fill your tank, locate the outside potable water fill port.
Most of the time, it's pretty clearly marked.
Below is an example of what yours may look like.
Sometimes it's inside a locked compartment, sometimes it's not.
If you have an older RV, just keep looking around the outside compartments until you find a hole that looks like it can fit a hose.
It's NOT the same hole that you use to stay hooked up to water as we talked about above.
The opening for the fresh water tank fill has a totally separate entry point.
NOTE: Some RVs (mainly motorhomes) do not have a potable water fill port. Instead, they have a valve that redirects water coming in from the city water inlet to the fresh water tank.
One other way you can fill water holding tanks is with portable water containers or bladders.
You can also fill these to help your water supply go even farther.
You then empty them into your portable water fill point (assuming your RV has one).
Doing so means you don't have to move your rig again to top-off your fresh water system.
Please note- these bags are notorious for leaking around the threaded area over time, or otherwise developing a leak, and may need to be replaced periodically.
Other methods are to purchase a large bladder that you can fill at the drinking water station.
You then utilize a free-standing water pump OR the water pump that came with your RV, to fill up your fresh water tank.
Filling Your Water Tank Using Collapsible Water Containers
Your RV Water System Pump
You will need to turn your RV water pump on to use tank-stored water when you are not connected to city water.
Locate the on/off switch and flip it to the 'on' position.
You have a pressurized fresh water system.
The pump may be in the 'on' position, but it won't necessarily be actively running.
It's designed not to activate until the pressure in your water lines drops.
The pump is set to keep the pressure in your RV plumbing lines at a certain pressure, usually about 40 PSI (pounds per square inch).
When the pump senses that the RV water system pressure drops below that (when you open a faucet, use the toilet, or take a shower) it turns on to maintain water system pressure.
Need to replace your water pump? Use the button below to open up the reviews and find the right type for your rig.
Most RV plumbing system pumps will pulsate when water is used.
So if you have water flowing for any duration, the pump will pulse on and off.
To lessen the pulsing, you can install an accumulator.
The video below is an example of a normal pump operation.
You can see that the RV plumbing system water pressure fluctuates when the faucet is being used.
If you listen closely, you can hear the pump turning on and off in the background.
Normal Water Faucet Pulsing
There are newer RV water pump models that also claim to lessen the above water system pulsation and noise.
Also, it's a good idea to keep your pump off until you need to use water.
This is just in case a leak in the water system happens.
You can avoid a big mess.
Be aware that when you first turn your pump on after filling your tank with water, the plumbing lines probably aren't filled with water yet (assuming the tank was previously run dry or had been sitting a while).
Therefore, you might hear your pump come on for a couple of seconds to prime the water system lines.
Don't be alarmed, it's perfectly normal stuff.
After a short period of time it should turn off until you use on a water fixture (faucet, shower, or toilet).
Pump Pulsing When You Aren't Using It?
When turned on, if your pump runs constantly, or pulses every few minutes and you aren't using your RV plumbing system, this is not good.
You are losing pressure which indicates you have a leak somewhere in the plumbing.
Turn off your water system pump and start trying to locate the leak before you have water damage.
Also, your water faucet or shower might sputter and spit the first time you go to use it after filling your tank.
This is normal.
It will happen until the RV plumbing lines are completely void of air.
The water might look weird, sort of whitish.
This is again normal and is caused by the air in the plumbing system mixing with the water.
Once the air has been purged from the water system lines, you will no longer hear sputtering or see the air filled water.
You should have your own dedicated water hose for filling your rig with fresh, potable water from a reputable water supply.
Fill your rig's freshwater tank until water starts to back out of the overflow hole.
Don't forget to put the cap back on after filling the fresh water tank.
Never fill your tank using the non-potable water hose at a dump station.
People use that hose to stick down their contaminated RV sewer hose to rinse it.
How To Find Water To Fill Your Fresh Water Tank
Unless you are filling your RV water system at a campground or from home, it can be a challenge to find water for filling your fresh water tank.
There are a few online places that can help.
There's a website called SaniDumps that is a dump and water locator.
Also, where there's a dump station, there's USUALLY potable water as well.
There are also many dump station reviews on the website Campendium.
Be Smart - Call Ahead
If you are looking at getting water from a campground but you aren't staying there, always call ahead.
Ask them if they will allow it and how much they charge.
Be aware that a lot of campgrounds in more northern regions, or at higher elevations turn off their water supply for winter.
This is another good reason to call.
Sucks to arrive in an area only to find out that you don't have any place to fill up your fresh water tank.
Might ruin your camping trip.
Some gas stations, and the occasional camping store, have fresh or 'potable' water that you can use for free.
Other times you can find a campground or RV park that will let you fill.
Usually they will charge somewhere from $5 to $20, depending on how greedy they are, how large your fresh water tank is, or what part of the country you are in.
Fairgrounds are another place that often has potable water for a price.
Use the old-school 'telephone' part of your smartphone to call around.
How Does Your Water System Pump Get Power?
Your fresh water pump needs power to run.
Where does it get power from?
It's a 12-volt device, so it uses your RV's batteries, which provide your motorhome or trailer with 12-volt (DC) power.
Even if you are connected to shore power (an outside electrical source) your pump will still only use 12-volt power.
You can learn more about the mysteries of camper power systems by reading our guide on how RV electrical systems work.
Filtering Your Fresh Water
Should you use a water filter when filling your fresh water tank?
You might think 'I don't drink the water from my faucets, so I don't need a filter'.
Well, that's only a partially correct statement.
Filtering the water that comes into your fresh water tank also filters the H2O that goes through your pump.
Filtering water before it goes into your water holding tank keeps tiny particles out of the pump.
Those unfiltered particles might otherwise damage the pump's diaphragm and eventually cause it to stop working.
You never know how good or bad the water quality is going to be during your camping trip.
It's best to use a filter whenever filling into your fresh water tank.
If your RV doesn't already come with a water filter installed (most don't), you will need to buy one that you attach to the end of your fresh water hose.
Simply attach it in between your fresh water hose and your camper and you're good to go to keep sediment from your RV water system.
Disinfecting Your Fresh Water Tank
Before you use your RV plumbing system for the first time, it's a good idea to disinfect the fresh water tank.
Do this ESPECIALLY if you plan to use it for drinking water.
It's also good practice to do this once or twice a year to keep it nice and clean.
How To Sanitize Your Fresh Water Tank
To eliminate the bleach smell and taste after sanitizing your fresh water tank, you can add a small amount of white vinegar to the tank when you fill it to drain it a second time.
You don't have to completely fill the tank, just enough to run sufficient water through the plumbing system so you get the vinegar solution through every fixture.
Run all your faucets, hot and cold, until you smell vinegar coming out.
Let it sit for a few hours.
Then empty your fresh water tank and lines completely and refill with fresh potable water.
What About Waste Water Tanks?
So far we've only discussed the fresh water tank, but what about waste water?
Your RV plumbing system also has a black water tank and one (or more) gray water tank.
You can learn all about these waste water holding tanks by reading our RV Septic Tank Guide.
Your RV's fresh water system isn't that complicated.
There are two options to get fresh water flowing thru the system - using the pump or being hooked up to a city water supply via a hose.
Now that you understand how to safely use your RV water system you are ready for your next camping trip!
He-llllo. I'm the co-founder of Camp Addict, which my biz partner and I launched in 2017. I frigging love the RVing lifestyle but in December of 2020, I converted to part-time RV life. Heck, I lived in my travel trailer for over 5.5 years, STRICTLY boondocking for pretty much all of it. Boondocking is a GREAT way to live, but it's not easy. Anyway, I'm passionate about animals, can't stand campgrounds, I hardly ever cook, and I love a good dance party. Currently, I can be found plotting and scheming whether or not to start collecting farm animals (or plotting my next RV trip!) at my beautiful new 'ranch' named 'Hotel Kellyfornia', in Southern Arizona.
Camp Addict co-founder Marshall Wendler brings his technical expertise to help explain RV products in an easy to understand fashion. Full-time RVing from April 2014 - December 2020 (now RVing about 50% of the time), Marshall loves sharing his knowledge of the RV lifestyle. Marshall spends the majority of his RVing life boondocking. He is the part of Camp Addict that knows 'all the things'. He's good at sharing his technical knowledge so you can benefit.