How to Winterize an RV Water System: Pump, Filters, Water Heater & Lines

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Winterizing an RV water system is about removing or protecting water anywhere freezing temperatures could damage plumbing, pumps, valves, filters, housings or appliances. The exact procedure varies by RV and installed equipment, so use this guide as a diagnostic checklist and follow the manuals for your coach, water heater, pump and accessories.

Before you begin

Turn off the water heater and allow it to cool. Disconnect city water. Locate the fresh-water drain, low-point drains, water-heater bypass, pump winterizing or siphon connection, filter housings and any appliances connected to the water system. If your manufacturer specifies antifreeze, use only RV/plumbing antifreeze intended for potable-water systems—never automotive antifreeze.

Complete RV water-system winterization checklist

Verify the manufacturer procedure. Tank-style and tankless water heaters, filter systems and appliance plumbing can require different steps.
Drain the fresh-water tank. Open the appropriate drain and relieve pressure in the system.
Drain the hot and cold plumbing. Open low-point drains and faucets as directed by the RV manufacturer.
Drain the water heater. Follow the heater manufacturer's instructions exactly, then place the heater in bypass if the system is designed for it. Never energize an empty water heater.
Protect filters and housings. Remove or bypass cartridges when the manufacturer calls for it, drain housings and do not leave trapped water where freezing could crack a housing or fitting.
Protect the pump and supply lines. If your RV uses an antifreeze method, draw approved RV antifreeze through the pump using the manufacturer-provided winterization connection or specified method.
Work through every branch. Protect hot and cold faucets, shower, toilet, outside shower, sprayers and any other connected fixtures according to the RV procedure.
Check optional appliances. Ice makers, washing machines, dishwashers and similar equipment often have their own winterization instructions.
Protect traps and drains. Follow the RV manufacturer's directions for sink/shower traps and holding-system components.
Document the setup. Photograph bypass-valve positions and label anything you changed so spring recommissioning is easier.

Filters and water softeners need special attention

Filtration equipment and portable softeners can retain water after the RV plumbing appears drained. A cartridge housing can crack if trapped water freezes, and filter media or softener resin may have storage requirements of their own. Do not pump antifreeze through filter media or a softener unless its manufacturer specifically permits it.

Read: Do I Remove My RV Water Filter Before Winterizing?

Compressed air or RV antifreeze?

Both methods are used on some RVs, but neither should be treated as universal. If using compressed air, stay within the pressure limit specified by the RV/plumbing manufacturer. If using antifreeze, follow the exact routing and bypass instructions for your coach. Some systems or appliances require additional steps regardless of the main method.

Spring recommissioning

Restore all bypass valves to their operating positions, flush the plumbing thoroughly, reinstall the correct filter cartridges, sanitize the fresh-water system as directed, inspect for leaks and verify pump operation. Make sure the water heater is full before restoring its heat source.

Common questions

Do I need to winterize if it only freezes overnight?

If freezing temperatures may reach water trapped in the RV system, damage is possible. Use the RV manufacturer's temperature/storage guidance rather than relying on how brief the forecasted freeze may be.

Should I put RV antifreeze in the fresh-water tank?

Not automatically. Many RVs have a pump winterization connection that avoids filling the fresh tank. Follow the procedure for your specific plumbing system.

Do I drain the water heater before bypassing it?

Generally the heater must be drained as part of winterization, but the exact drain and bypass sequence depends on the heater and RV. Follow the heater manual.