RV Water Pump Running But No Water? Complete Troubleshooting Guide 202

Tools & Parts Needed

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Recognizing the Signs

If you're experiencing this issue, you're not alone. Here's what's typically happening and how to address it.

What You Might Notice

When your RV water pump runs constantly but no water comes out after de-winterizing, the most common cause is air trapped in the water lines or a pump that needs priming.

Root Causes

Air in the system is by far the most common issue. During winterization, antifreeze displaces water throughout your plumbing, leaving air pockets that must be purged. Pump priming issues occur when the pump loses its prime and can't create enough suction to draw water from the tank.

Clogged strainers or filters can also cause this problem. Many RV water systems have inline filters or strainers that can become blocked with debris or crystallized antifreeze residue. Check and clean these components if accessible.

Frozen or damaged components from winter storage can prevent proper water flow. Even if you winterized properly, extreme cold can damage pump diaphragms, crack fittings, or freeze residual water in low spots.

What to Grab

• Basic screwdriver set
• Adjustable wrench
• Flashlight or headlamp
• Fresh water (for refilling tank)
• Towels for cleanup

The Repair Process

1. Verify all faucets are closed: Make sure every faucet, including bathroom, kitchen, and outdoor shower valves are completely shut off. Even a slightly open faucet can prevent the system from building pressure.
2. Check water tank level: Even though you mentioned the tank is full, double-check the actual water level with a flashlight. Tank gauges can be inaccurate, especially after winterization.
3. Verify electrical power: Ensure the pump is receiving 12V power by checking fuses, breakers, and that electrical connections are secure.
4. Prime the water pump: Turn on the water pump, then immediately open the faucet closest to your pump (usually the kitchen sink). Warning: Do not let the pump run dry for more than a few minutes as this can damage pump diaphragms and seals. Let it run for 2-3 minutes. You should hear the pump tone change and eventually see water flow as air is purged from the system.
5. Work through each faucet systematically: Starting with the closest faucet to the pump, open each one individually until water flows steadily. Allow the pump to run continuously during this process to maintain pressure and effectively purge air from the lines. Move to progressively farther faucets (bathroom, shower, outdoor connections).
6. Check for leaks: While the pump is running, inspect all visible plumbing connections, especially around the pump itself, for leaks that could prevent pressure buildup.
7. Inspect pump connections: Turn off 12V power to the pump before inspecting electrical connections. Ensure the intake line from the water tank is properly connected.
8. Test pressure switch: If water flows but the pump won't shut off, the pressure switch may need adjustment or replacement. Most RV pumps have an adjustable pressure switch that can be fine-tuned.

When It's Time for Expert Help

Contact an RV service technician if you experience any of these issues: No electrical power to the pump despite checking fuses and breakers, pump makes grinding or unusual noises indicating internal damage, water flows but pump cycles constantly after trying all troubleshooting steps, or visible cracks or damage to the pump housing. Additionally, if you're uncomfortable working with 12V electrical systems or accessing plumbing connections, professional help ensures the job is done safely.