How To Fill Your Fresh Water Tank If You Don’t Have A Gravity Fill Spot [Video Included]

Most all RVs, Fifth Wheels and Travel Trailers have onboard fresh water tanks which are used when you aren’t hooked up to campground or city water. The way these fresh water tanks are filled differ depending on your RV. In this post I will cover how to fill your fresh water tank if you don’t have a gravity fill spot.

We have a Winnebago Micro Minnie 2100BH which has a Gravity Fill spot like this:

Gravity Fill Spot On RV

Other RV’s only have a pressurized fill spot like this:

Fresh Water Fill Connection

Both work very well to fill when you are at a campground, you simply connect one end of your hose to the water spigot and the other end either goes into the gravity fill spot or to the fresh water connection on your RV then turn on the spigot and run until your tank is full.

When you aren’t connected to city water, the gravity fill RV’s can still be easily filled by just pouring a jug of water into it, however, RV’s with a fresh water connection that requires pressurized water can’t be filled as easily.

I came up with a simple pump system that runs off 12v from your car’s cigarette lighter.

Pump System Supplies

I found all of these supplies at Walmart and they costed about $35 for the pump system. A similar water jug is also available at Walmart if you don’t already have one, but is an additional $15 – $20.

Here are these supplies on Amazon if it’s easier to order for you, but the prices are much better at Walmart.

12v Cigarette Lighter Plug

Bilge Pump

5/8″ RV Fresh Water Hose

Medium Hose Clamp

Small Butt Splices

Food Grade Bucket

6 Gallon Water Jug


To put the system together, first connect the positive wire of the cigarette lighter to the positive wire on the bilge pump using a butt splice and crimping it properly. Then do the same with the negative wires.

Pump to Cigarette Lighter Connection

Next, cut the female end of the hose off and slide a hose clamp onto the hose. You will connect the male end to your RV’s fresh water connection. The bilge pump I bought had a hose outlet for a 3/4″ hose, so it is important to get at least a 5/8″ diameter hose. I had to make a couple of slits on the end of the hose to fit it onto the pump. It took a little elbow grease to get the hose to fit onto the pump’s outlet, but it can be done and the snug fit helps making a good seal.

Bilge Pump with Hose Connection

Then slide the hose clamp up to the proper spot and tighten.

That’s pretty much it for assembly!

How to Use the System

To use the system, place the pump into the food grade bucket.

Pump in bucket

You will then pour water from your 6 gallon water jug into the food grade bucket being careful not to get the cigarette lighter or the butt splices wet. The rest of the wire coming from the pump can be submerged in water.

Filling Bucket

After the bucket is full, connect the male end of the water hose to your RV’s water fill connection.

Fresh Water Fill Connection

Now you can plug the cigarette lighter into your car’s cigarette lighter plug. You may or may not need to turn your car on when doing this. With the shorter wires that came with the cigarette lighter plug and the pump, I had to put the bucket on the floor of the passenger seat.

Running the pump system from the car

Once plugged in, the pump will start to run and pump the water from the bucket through the hose and into your RV!

You can add water to the bucket as the pump empties the bucket. Just be careful not to spill a bunch of water in your car. I speak from experience!

How-To Video

Hopefully this will help the next time you need to fill your RV’s fresh water tank through the fresh water connection.

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Fill RV Water Tank

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