Air in Your TAB Water Lines: How to Fix It (TAB 360 & TAB 320)

If you’ve turned on your water pump and gotten nothing but a hissing pump and a dry faucet — or worse, your pump won’t stop running even though no water is coming out — you almost certainly have air in your water lines. Good news: it’s one of the easier TAB issues to fix, and you don’t need any tools.

Here’s how I diagnose it and what I do to get water flowing again.

The Two Symptoms

You’ll usually notice one of these:

• No water from the pump or hot water tap. You flip the pump on, you hear it run, but nothing (or only a sputter) comes out of the faucet.
• The pump won’t stop running and the lines won’t pressurize. The pump cycles or runs continuously because it can’t build pressure — air compresses, water doesn’t.

Both point to the same thing: air got into your water lines somewhere and broke the prime.

How This Usually Happens

The most common culprit I see, especially with newer TAB owners, is running the pump on a mostly empty freshwater tank. The pump pulls in air instead of water, and once that air is in the lines, it stays there until you push it out.

A close second: leaving the pump switched on while you’re filling the freshwater tank. There’s no reason to have the pump running during a fill — and if you’re using the Power Fill setting on the Nautilus, the pump should be off.

How to Fix It

Option 1 (Easiest if you have it): Connect to City Water

If you’re at a campsite with a water hookup, this is the fastest fix:

1. Turn off your water pump.
2. Connect your TAB to city water as you normally would.
3. Open the kitchen or bathroom faucet and let it run.
4. You’ll hear sputtering and see bursts of air at first — keep it running until water flows smoothly and steadily.
5. Once the sputtering is gone, switch the Nautilus to dry camping mode and turn the pump on. You should now have full pressure from the tank.

The city water pressure pushes the trapped air out through the open faucet. It usually takes 30 seconds to a minute.

Option 2: Prime Through the Cassette Toilet

If you don’t have city water access, use the cassette toilet’s flush button to help draw water through the system. Note: this assumes your TAB has the wet bath with cassette toilet. If yours doesn’t, you’ll need to find a city water hookup or another pressurized source.

1. Make sure you have water in your freshwater tank — at least a third full is safer.
2. Turn the pump on.
3. Open a faucet (kitchen or bathroom) and press the water flush button on the cassette toilet at the same time.
4. Hold the toilet flush until you see water flowing smoothly through both — the toilet line helps pull air through the system.
5. Once it’s running clean, close the faucet.

I walk through this in a short video on YouTube:

One Thing Not to Do

Don’t keep running a dry pump while you troubleshoot. Running a water pump without water can damage it. If your first attempt doesn’t work within a minute or two, turn the pump off, check your freshwater level, and try again.

How to Avoid This Next Time

• Don’t run the pump on a near-empty freshwater tank. When you see the tank getting low, switch to city water if available, or refill.
• Turn the pump off before using Power Fill. The Nautilus uses city water pressure to fill the tank — your pump should not be running.
• Turn the pump off when you’re on city water. City water provides its own pressure; the pump isn’t needed and can introduce air if the tank is low.

These three habits will save you from most air-in-the-lines situations.

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If this saved you some frustration at the campsite, subscribe on YouTube for more TAB tips like this one — and drop a comment if you’ve run into this and solved it a different way. I love hearing what works for other owners.