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1 Easy Trick to Boost Your RV’s Freshwater Tank Capacity

Does your RV’s fresh water tank seem to be too small for your needs?

If you’ve tried the usual water conservation tricks while boondocking and you’re still running dry too soon, here’s one easy way to get more fresh water into your tank when you camp.

With a little basic electrical and plumbing knowledge, you can modify your RV’s fresh water system to easily fill your tank from collapsible jugs (or any external source) using your existing water pump.

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What You’ll Need:

Before doing this modification, you’ll need a place for the extra fresh water. You can buy inexpensive collapsible water jugs from a sporting goods store or invest in a portable RV water tank that sits in your auxiliary vehicle.

Fill up the containers with additional potable water before you head out to your dry camping destination.

increase potable water RV

Step 1: Add Fill Tube

Many RVs come with a winterization bypass hose. If yours doesn’t, just insert a tee valve* in between the the input side of the pump and the freshwater tank, then add a short length of clear flexible tubing that will serve as the input hose. Add your hose clamps and for maximum safety, tighten clamps with a wrench, not a screwdriver.

*NOTE: Measure carefully for the new hose and double-check the diameter of your existing hose before buying. You want to purchase the correct size tee valves to fit your current plumbing and the new supply hose.

Step 2: Add Bypass Valve

Add the second tee valve to the output hose originating from the water pump to the pressurized water lines.

Install new hose clamps and attach a length of braided hose long enough to reach the pressure relief hose on top of your freshwater tank.


Step 3: Add Redirect Valve

Splice another tee valve into the relief hose to redirect water back into the tank.

Ensure the valve directs water in the correct direction when turned and install new hose clamps.

Step 4: Create a Power Supply

This is where basic electrical skills come in handy. Run a wire from the nearest DC power source in your RV and splice that wire into the positive side of your water pump’s power supply.

Add the rocker switch to the power supply so you can turn the pump on and off by yourself. This will prevent the need to have someone inside operating the pump.

You’re now ready to add more water to your freshwater tank.

increase RV freshwater capacity


RV freshwater mod bypass modification diagram
Setup installed in Team Agreda 5th wheel

First go inside your RV to make sure the water pump is turned off.

Next, head outside and refill your water tank by dipping the clear PVC hose that’s attached to your pump, into the external water supply source.

Turn the tee valves in succession to direct water into the tank.

Be sure to keep the freshwater supply inlet cap open to avoid air pressure build-up inside the tank.

When your tank is full, turn off the rocker switch and always return the tee valves to their proper positions to resume normal functioning of your freshwater system.

Watch Jim Nelson of LiveWorkDream demonstrate this setup on his 5th wheel:


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