How Does an RV Water Pump Work?

Everything an RVer Needs to Know

Your RV fresh tank is a greedy jerk.

Why? Well, it just LOVES hoarding all that nice fresh water for itself. Picture this: you're boondocking in the middle of nowhere, sweat rolling down your face on a hot summer's day. All you need is a glass of ice-cold water before you start seeing desert mirages of lakes that aren't there. Problem is, your fresh water tank has all the water, and it isn't sharing.

That's where your water pump comes in. Picture your water pump as your savior, the hero who delivers fresh water from the greedy grasp of your tank and to your parched, grateful lips (and your shower, sink, etc).

So, how does this benevolent hero function? How do you make him work for you? The dealer or individual who sold you your RV probably pointed out the control panel and told you it was how you controlled the water pump, but they likely left you with a few questions. When do you use it? Does it run off your battery? Do you just leave it on all the time? Where does it even live in your RV, in some magical vortex?

So, let's jump into all the main info you need to operate your water pump, what you should be aware of, and what you should (and shouldn't) expect from a properly functioning pump. Together, you and your water pump can release the sweet H20 from that greedy fresh tank and deliver flowing water to your entire RV. Let's get started!

Meet your guide: Pumpseidon, God of RV Water Pumps

In this article:

How Does an RV Water Pump Work?
How (and When) to Turn On and Use an RV Water Pump
Can I Leave My RV Water Pump On?
How Long Should an RV Water Pump Run?
How to Quiet an RV Water Pump
Where is the Water Pump Located in an RV?
Does an RV Water Pump Run Off Battery?
How to Winterize an RV with a Water Pump

How Does an RV Water Pump Work?

An RV water pump works by sensing the pressure in your water lines and working to maintain it at all times. When the pressure drops (such as when you turn on a faucet), your pump will keep pushing out water until it achieves the correct pressure again (which happens when you turn off the water). Thus, the pump will only run when the water is running and releasing pressure in the lines.

This process of turning on, pumping water until the right pressure is reached, and turning off again is known as cycling.

Cycling is normal when you have a faucet open and are releasing pressure from the line. However, if your water pump is cycling when no faucets are open, this is a sign that you're losing water pressure somewhere else, such as through a leak. (See the section "How long should an RV water pump run" below for more info.)

LIfecycle of an RV Water Pump Infographic

How (And When) to Turn On and Use an RV Water Pump

Many campers think they have to run their pump whenever they camp, but this isn't necessarily true. You only need to run the pump when you use your fresh water tank (remember that greedy jerk?). You don’t need to turn on the pump when you're using a city water connection (such as at a campground with water hookups) because this water is already pressurized. (Indeed, water pressure from city water connections can be a bit on the wild side, which is why we recommend using a water pressure regulator at all times.) So, you'll really only need your water pump if you're boondocking.

In fact, your city water doesn't even run through your water pump. So you won't get any "extra pressure" by turning on your pump while using city water.

Turning on and using your RV water pump is pretty straightforward. If you're using water from your fresh water tank supply, you essentially just turn on the pump using the control panel inside your RV. And that's really all there is to it!

Fill the freshwater tank.

Go to the control panel and turn the water pump on.

Enjoy fresh water. You can leave the pump on until the end of your camping trip.

Can I Leave My RV Water Pump On?

Yes. Water pumps don't draw much power even when running, and since they run on demand (when your water is running), they really have a limited power draw. Most campers leave their water pump on while boondocking and using their freshwater tank.

However, there are certain circumstances in which you'll probably want to shut off your pump:

1) When your fresh water tank is empty. Some newer-model pumps can run for several hours without water, but for the most part, dry-running your RV's water pump for extended periods of time is a good way to damage it. Always turn off your water pump switch whenever there's no water in your system.

2) When you're driving, or if you'll be away from the campsite for a while. In some cases, a faucet can shake itself on while you're driving down a bumpy road, or a leak can occur while you're away from your rig. If this happens, you absolutely don't want your pump pressurizing that water and spouting it out everywhere. Just think of turning off your water pump the same as you would locking your door and turning off your lights—that is, part of your "closing up" routine before you leave.

3) If you switch to city water. It won't hurt anything if you forget and leave the pump on, but it can continue to pump out water from your fresh tank when it's not necessary.

An RV water pump? Perfectly harmless.

An RV water pump that's found a new pipe leak while you're out hiking all day? More capable of wreaking havoc than a bored puppy with a shoe craving.

How Long Should an RV Water Pump Run?

If you're taking a shower or you have a faucet open, your water pump will run continuously until you shut the water off and it can re-pressurize the lines.

However, your water pump should not be running if you're not running water. The depressurizing of water lines is what tells the pump to run, so if it's running when no faucets are open, that pressure is leaking out somewhere. This means that you likely have a leak.

How to Quiet an RV Water Pump

If your water pump is super loud, you might find yourself raising your voice to talk over it or avoiding using water at all after the kids have gone to bed. One of the chief complaints about RV water pumps is how noisy they can be, but they don't necessarily have to be. (Case in point, our team installed a Seaflo pump in a rig recently, and I couldn't even hear it over the rain outside.)

If the sound of your water pump jolting to life sets your teeth on edge, you have some options for quieting the pump:

A lot of the water pump noise comes from the pump vibrating against the hard wooden surface it's mounted on. So, one easy, affordable way to quiet your pump is to detach the pump and re-mount it on a foam or rubber pad. If your water lines are vibrating against any hard surfaces, use pipe insulation to quiet them. You can also purchase a pump silencing kit like this one to help reduce surges in water pressure and minimize pipe vibrations.
Use an accumulator tank. These tanks allow the pump to reach shut-off pressure more smoothly, which leads to quieter operation. They install near your water pump and are similar in size.
Replace your water pump with a quieter one. This probably isn't your first choice, but if all else fails, you may just need to find a quieter pump.

You can install a foam pad beneath the water pump to quiet the vibrations against the ground

Pictured: Accumulator tank installed near water pump

Where is the Water Pump Located in an RV?

RV water pumps can be surprisingly difficult to find; they aren't usually on display front and center, and every RV is different. In fact, the best method our installers have found for locating RV pumps is to run them (with water, of course) and just listen for the source of the noise. Usually your pump will be hidden behind an interior panel that will need to be removed so you can access it. Some common locations include under your sink, beneath your cabinets, at the bottom of your closet, or even under the bed! However, pumps are typically located within a few feet of your fresh water tank.

Water Pump Located In Bottom Cabinet in RV

Does an RV Water Pump Run Off Battery?

Yes, your RV water pump runs off your rig's 12V battery. As mentioned above, your water pump doesn't draw much power, so you don't generally need to worry about it draining your battery.

How to Winterize an RV with a Water Pump

Water pumps aren't limited to just pumping water—they're also great tools for pumping antifreeze through your system when you winterize.

How does this work? Many water pumps have a siphon hose specifically for pumping in antifreeze. Normally, the valve to the fresh water tank is open and the siphon hose valve is closed. For winterization purposes, you'll open the siphon hose valve and close the fresh water one. Then, you'll just stick the hose into a bottle of antifreeze, turn the pump on, and let it do the work.

For a more detailed explanation of the winterization process, check out our article and video here.

Hopefully this helped remove any doubts about using your RV water pump. Still have questions? Leave them in the comments below!

About Amber S.

As a content writer for etrailer, I might spend my morning loading and unloading a bike on five different bike racks to figure out which is easiest to use. I might be in the parking lot, taking pictures of an impressive RV battery setup our techs came across in the shop and discussing the benefits of the setup with the owner. I might spend an afternoon in a manufacturer training classes for some hands-on experience with new products, and then sit down to assemble all this information into a coherent article.

At etrailer, one of our core values is that we are always learning, and I learn something new every day. I start each morning with the goal in mind of taking all of this information and figuring out the best way to answer the questions people ask us (and the ones they don’t know to ask yet), and helping people get the solutions they need to make their lives easier, safer, and more fun. I’m a DIYer at heart, so it brings me great joy to help a fellow DIYer find what they’re looking for, whether that’s a product, an answer, or a community.

Related Products

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Written by: Amber S.

Updated: 1/25/22

Nick

5/6/2023

I have had som problems with campsites having low water pressure when hooked up to 'city' water. Could I run city water pressure on the inlet side of my RV pump to increase the pressure? Will that damage the pump?

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