How To Blow Out Camper Water Lines: The Complete Winterization Guide

Blowing out camper water lines is a critical maintenance procedure that uses compressed air to evacuate stagnant water, preventing catastrophic pipe ruptures during sub-freezing temperatures. This process requires maintaining air pressure between 30 and 40 PSI to protect delicate PEX plumbing fittings while ensuring every low-point drain and fixture is completely purged of moisture.

Essential Equipment and Pre-Procedure Requirements

Before beginning the winterization process, ensure you have the necessary components to maintain a closed, pressurized system. Attempting to blow out lines without a proper regulator often results in over-pressurization, leading to blown seals, cracked faucet cartridges, or detached plumbing junctions.

• Essential Equipment:
• An air compressor capable of delivering consistent, low-volume pressure.
• A blowout plug (specifically a 1/2-inch NPT adapter) designed to connect your air compressor hose to the city water inlet.
• An adjustable air pressure regulator to lock output at 30 to 40 PSI.
• A standard screwdriver for removing access panels or drain plugs.
• Water heater bypass kit (if not already installed) to prevent filling your 6-to-10-gallon tank with air.
• Knowledge of your specific RV model, specifically the location of the water heater, the fresh water tank drain, and all low-point drain valves.
• Estimated duration: 45 to 60 minutes for a standard travel trailer or motorhome.

Sequential Workflow for Clearing Residential-Style RV Plumbing

Step 1: System Isolation and Tank Drainage

Start by disconnecting from shore power and city water sources. Locate your fresh water tank drain valve and allow it to empty completely. If your RV is equipped with a water heater, turn off both the gas and electric heating switches. Open the water heater’s pressure relief valve, remove the drain plug or anode rod, and allow the tank to drain fully. Once empty, flip your water heater bypass valves to the bypass position. This step is non-negotiable; bypassing the heater prevents you from forcing air through a massive volume of water, which is inefficient and potentially damaging to the heater’s internal gaskets.

Step 2: Engaging the Low-Point Drains

Locate the low-point drain lines underneath the RV. These are typically color-coded—blue for cold and red for hot. Open both valves and allow gravity to do the initial work. Once the major flow stops, leave these valves open. This creates the necessary exit path for the water forced out by the compressed air.

Step 3: Integrating the Compressed Air System

Attach your blowout plug to the city water inlet of your camper. Connect your air compressor hose to the blowout plug, ensuring your inline regulator is set strictly between 30 and 40 PSI. Gradually introduce air into the system. You will hear air and water mixture discharging from the low-point drains. Continue this until only air escapes. Once finished, close the low-point drain valves to maintain pressure for the internal fixture purge.

Step 4: Individual Fixture Purge

Work your way from the fixture closest to the water inlet to the one furthest away. Open the cold side of the bathroom faucet until only air spits out, then close it. Move to the hot side and repeat. Follow this exact sequence for the kitchen sink, the shower, and the outdoor kitchen faucet. Do not forget the toilet flush valve, which is a common site for hidden water accumulation. If your unit features a washing machine hookup or an ice maker, these must be cycled through their own purge modes or manually triggered to clear the intake valves.

Step 5: Final System Clearing

After all faucets have been cleared, revisit the low-point drains one last time to expel any final droplets that may have migrated during the fixture purge. Once no more water ejects, turn off the compressor, disconnect the blowout plug, and ensure all faucets are left in the middle, partially open position to alleviate any residual pressure trapped behind the valve cartridges.

Technical Specifications for Plumbing Integrity

Common Site Failures and Field Fixes

• Root Cause: Blown Faucet Cartridge.
• Actionable Fix: This occurs when air pressure exceeds 50 PSI. Ensure your inline regulator is functioning and calibrated correctly before connecting the hose. Replace the internal cartridge using a standard adjustable wrench and manufacturer-specific replacement parts.
• Root Cause: Toilet Flush Valve Leak.
• Actionable Fix: Residual water in the valve body freezes and cracks the plastic housing. Always depress the flush pedal during the air-purge process to ensure the seal opens and clears internal water.
• Root Cause: Water Heater Tank Damage.
• Actionable Fix: Failing to bypass the tank forces sediment into the heater. If you forgot the bypass, drain the tank and flush it with a vinegar solution once the season starts to clear out debris from the check valve.
• Root Cause: Persistent Puddles under RV.
• Actionable Fix: This is often caused by a failing check valve at the city water inlet. If water continues to leak out of the city port after the blowout, the spring-loaded internal check valve has likely failed and requires a replacement city water inlet assembly.

Frequently Asked Questions

Can I use a standard pancake compressor for this task?

Yes, a small pancake compressor is perfectly adequate for blowing out water lines. Because you are maintaining low pressure (30-40 PSI) and low volume, the limited tank size of a pancake compressor will suffice for most RV sizes.

Is blowing out lines enough, or do I need RV antifreeze?

While blowing out lines removes the bulk of the water, it cannot guarantee 100% moisture removal from every low-lying pipe "trap" or pump housing. Most experts recommend blowing out the lines first and following up with RV-specific propylene glycol antifreeze to protect any remaining microscopic water droplets.

Should I remove the water filter before blowing out the lines?

Absolutely. Remove the water filter cartridge from its housing before beginning the procedure. Leaving the filter in place will trap air, restrict flow, and potentially burst the filter housing, creating a significant mess and potential plumbing failure.

Does it matter if the RV is level during the blowout?

Leveling your RV is highly recommended during this process. A level orientation ensures that water naturally flows toward the low-point drains rather than pooling in the center of a pipe run, which would prevent the compressed air from successfully evacuating the lines.

How do I protect the water pump during this process?

The water pump is designed to handle water, not compressed air. When using a blowout plug at the city water inlet, ensure the pump is turned off. The pressurized air will reach the outlet side of the pump; if you wish to clear the pump itself, disconnect the intake line and run the pump dry for no more than 10-15 seconds.

Establish a consistent winterization schedule every autumn to protect your investment from costly freeze-related plumbing repairs. Reach out to our technical support desk for specific diagrams related to your RV’s unique plumbing manifold configuration.