RV Water Pump Not Working?
RV water pump not working? Check the switch first. What we learned when our rented Class C's toilet ran dry, plus how to check the fuse, tank, and prime.
Carlos Lopez
10/6/20265 min read
Why Is My RV Water Pump Not Working?
Check the water pump switch first. When you're running off the fresh water tank instead of city water, the pump has to be on, and it's easy to miss. Ours was on the control panel by the door. If the pump stays silent, check its fuse or breaker. If it runs but nothing comes out, check the tank level.
Here's the situation. Nancy and I rent RVs. We don't own one. Over Labor Day we took a rented Class C to Greenbrier Campground in the Great Smoky Mountains with Macie and Mindy.
Setup went the way it usually does. Dog pen up first, power plugged in, then we unloaded the one storage bay we had. After that we sat down for an hour or so, relaxed, and took pictures while Nancy took Macie and Mindy for a walk. Then we noticed the toilet had no water in it.
It took a minute. Then: oh yeah. The water pump switch.
The owner had walked us through the rig at pickup, switch panel included. We forgot most of it. We're just not used to switching a water pump on and off. We flipped the switch, hit the foot pedal, and water came into the bowl.
We were on the fresh water tank the whole trip. We never connected to the campground's city water. Honestly, we weren't there long enough to figure that one out. That detail turns out to matter, and it's the first thing to understand if your RV water pump isn't working.
Where Is the Water Pump Switch in an RV?
A water pump switch is the on/off control for the pump that moves water from your fresh water tank to the faucets, shower, and toilet.
In our rented Class C, it was by the entrance, on a plate with other switches and a small screen. Many RV manuals describe a monitor panel, a small display that shows approximate fresh, gray, and black tank levels, propane, and battery condition. If your rig has a panel with a screen, start your search there.
Two things we learned afterward, reading owner's manuals and RV forums:
Some RVs have more than one pump switch. Owners describe switches on the main panel, in the bathroom, and by the outside shower, and on some rigs they're wired so either switch can turn the pump on or off. If one switch doesn't seem to do anything, look for another.
On city water, you don't need the pump. Tiffin's owner's manuals explain that city water is already pressurized, so the pump isn't needed when you're hooked up. The pump only matters when you're running from the fresh water tank, which is exactly when we forgot it.
Why we lean this way: before you leave the pickup, ask the owner to point at the water pump switch, and take a photo of the panel. It would have saved us an hour of dry toilet.
Why Won't My RV Toilet Fill With Water?
An RV toilet fills from the RV's own fresh water system. If the pump is off and you're not on city water, there's nothing to fill it. That's what happened to us.
We just pressed the foot pedal after flipping the switch, and water came into the bowl. If your toilet is a Thetford Aqua-Magic, the owner's manual says to press the pedal about halfway to add water and all the way down to flush.
If the switch is on and the toilet still won't fill, the problem is upstream of the toilet. The next two sections cover that.
RV Water Pump Running but No Water
We haven't lived through this one, so here's what we found researching it.
SHURflo, one of the major RV water pump makers, publishes a troubleshooting guide. For a pump whose motor runs but won't prime or sputters, its first question is whether there's water in the tank, or whether air has collected in the water heater.
RV owners on forums add a few more things to check:
A closed valve. The valve between the fresh water tank and the pump may be closed, for example if it was left in the winterizing position.
A lost prime. Once you've ruled out an empty tank and a closed valve, the common advice is to open a faucet and run the pump until water comes out.
A pump that won't stop running. If it keeps running with every faucet closed, SHURflo's guide points to air trapped in the pump head or on the water heater side, or a bad city water or tank-fill valve. Owners also note that an empty tank will keep a pump running, because it never builds pressure, and that letting it run dry can damage it.
Renter note: if you've checked the tank and the valve and it still won't move water, call the owner before you start opening panels. It's their rig.
RV Water Pump Not Turning On? Check the Fuse
If you flip the switch and hear nothing at all, SHURflo's guide for a pump that won't start says to check the electrical connections, the fuse or breaker, the main switch, and the ground connection.
A technician's answer on eTrailer adds two useful points. There can be more than one fuse, often an inline fuse at the pump and another at the RV's DC distribution panel. And a fuse can look intact and still not pass power, which is why techs test it with a multimeter instead of just looking at it.
We haven't had to check a pump fuse ourselves. In a rental, our first move would be calling the owner to ask where it is.
RV Water Pump FAQ
How do RV toilets work?
Many RV toilets, including Thetford's Aqua-Magic line, use fresh water from the RV's own water system to fill and rinse the bowl. Pressing the foot pedal partway adds water, and pressing it all the way flushes into the holding tank. That fresh water comes from the water pump when you're on the tank, or from a city water hookup, so if neither is on, the bowl stays dry.
How do you flush an RV toilet?
On Thetford Aqua-Magic models, the owner's manual says to press the foot pedal all the way down to flush and about halfway to add water. If no water comes in, make sure the water pump is switched on or city water is connected. Turning the pump on is what fixed ours.
How do you prime an RV water pump?
Make sure the fresh water tank has water in it and the valve between the tank and the pump is open. Then turn the pump on and open a faucet until water runs steadily. RV owners generally describe these pumps as self-priming once there's water to draw. If it still won't prime, check the owner's manual, or on a rental, call the owner.
How do you fill an RV fresh water tank?
It depends on the rig. In Tiffin's owner's manuals, the fresh water tank fills from the city water connection by turning a valve to the tank-fill setting, and because there's no automatic shut-off, you watch the level on the monitor panel while it fills. Other rigs have a separate fill port. We didn't fill ours. On a rental, ask the owner how they want it done.
KEEP EXPLORING
Camping With a Portable Dog Fence: how we set up the dog pen on this same trip.
Our RV camping checklists.
Funny RV camping shirts, made by people who forget the water pump switch.
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