Preparing Your Pure Water Window Cleaning Equipment for the Winter

Unger Enterprises Marketing | December 16, 2025

Packing up your outdoor window cleaning tools for the winter? Winterizing pure water window cleaning equipment is essential to protecting your investment and preventing damage caused by freezing temperatures. With the potential for prolonged downtime, if your pure water tools are not winterized, and water freezes within the system, you may need to replace or repair damaged parts when your season picks up in the Spring. Not only can this be a costly repair, but it also keeps you from performing your job until the necessary repairs are made.

The Risk of Not Winterizing Your Pure Water Equipment

Pure water window cleaning systems often include waterfed poles and cleaning brushes that use deionized or purified water. If the system or the accessories contain any water as they head into storage, and the temperatures drop below freezing, the remaining water can freeze and potentially cause several issues.

When frozen, the volume of water increases by approximately 9%. This means that ice occupies about 9% more space than the equivalent amount of liquid water. While 9% may not sound too threatening, the expansion is enough to exert considerable pressure on the system components. The pressure can lead to potential cracks in the fittings, dry and cracked membranes, or other types of damage that can reduce the system’s efficiency or render it inoperable.

The other issue with leaving water in the pure water system is that it can create the ideal environment for mold and bacteria to grow, which can impact the quality of the purified water when used next.

How To Winterize the Unger HydroPower NANO Window Cleaning System

The HydroPower® NANO System is designed for use in ambient temperatures above 40°F (5°C). When temperatures fall below this range—or if the system will not be used for more than 14 days—it must be properly drained, and the membrane protected before storage.

Important Notes before you begin:

• Always disconnect the system from the water source before servicing.
• Never store the HydroPower NANO in freezing conditions.
• Membrane protection is required if the system will be idle for extended periods.

How to Protect the NANO Membrane for Winter Storage

To prevent mineral buildup and preserve membrane performance during storage, Unger recommends using Unger Membrane Care Fluid. One 1‑liter bottle is required per system. This process protects the membrane from drying out, scaling, and performance loss during non‑use. As an alternative, the system can be run weekly for approximately 30 minutes, but membrane care fluid is the preferred method for winter storage.

To protect the membrane, you can view the step-by-step process on page 22 of the user manual or proceed as follows:

Step #1: Ensure the concentrate hose is connected, as the membrane care fluid will flush out through this line.

Step #2: Use the filter key to loosen the pre‑filter housing.

Step #3: Remove the combi pre‑filter and the HydroPower Ultra Resin pack and discard any remaining water. Keep both components clean and protected from dust and dirt.

Step #4: Insert the gray suction pipe into the pre‑filter housing, making sure the holes are positioned at the bottom.

Step #5: Fill the pre‑filter housing with Unger Membrane Care Fluid, then reinstall and secure the housing using the filter key.

Step #6: Ensure the HydroPower Ultra resin tank top cap is securely installed (without the resin pack inside – The resin itself needs to be stored in sealed and labeled containers).

Step #7: Set the concentrate valve to WORK and turn the Flow Optimizer Dial to PURE. Turn on the tap water supply and allow the system to run for approximately 5–10 seconds, until the pre‑filter housing fills with clear liquid.

Step #8: Turn OFF the water supply immediately and disconnect tap water supply.

The membrane is now protected, and the HydroPower NANO is ready for indoor winter storage.

How To Winterize the Unger HydroPower RO Window Cleaning System

The HydroPower RO system is designed for use in temperatures above 40°F. So when temperatures drop or when you know the system will not be used for an extended period (e.g. winter, holidays, etc.), you must drain your units and hoses after use and protect the membrane against mineral deposits. For this purpose, there is the Unger Membrane Care Fluid. You need one bottle (1l) to treat the membrane.

This product helps preserve the current state of the membrane and prevents reduced performance and/or damage after non-use. Alternatively, you can run the unit once a week for approximately 30 minutes to rinse the membrane.

To protect the membrane, you can view the step-by-step process on page 27 of the user manual or proceed as follows:

Step #1: Turn OFF the HydroPower RO.

Step #2: Ensure the concentrate line is connected. The membrane care fluid will flush out through the concentrate line. (Reference the SDS for proper disposal)

Step #3: Use the filter key to loosen the housings. (see Image A)

Step #4: Remove the two filter cartridges (left and right) and discard the water. Keep the pre-filter and resin filter protected from dust and dirt. (see Image B)

Step #5: Insert the gray suction pipe into the left blue housing of the pre-filter. The holes must be on the bottom of the tube. (see Image C)

Step #6: Fill the pre-filter housing with membrane care fluid and secure the housing on the unit using the filter key.

Step #7: Secure the empty resin housing on the unit using the filter key.

Step #8: Turn the upper switch to “WORK” and the lower to “PURE”. Turn on the tap water supply. Wait until the pre-filter housing is no longer green and filled with clear water. This takes approximately 5-10 seconds.

Step #9: Stop the unit immediately by turning it to OFF.

Now the membrane is protected and you can store the HydroPower RO system.

How To Winterize the Unger HydroPower Ultra Window Cleaning System

Unlike the RO system, there is no storing process for the Hydropower Ultra when you’re not using it for extended periods. If planning to continue use of the system during colder weather, it’s important to do so with caution and to avoid water pooling, which could freeze, creating a dangerous slip hazard.

You also need to ensure that the system is protected against frost. The temperatures in the operating area must be at least 15°F. The water temperature should not exceed 86°F, and maximum operating pressure is 116 psi (8 Bar).

When in storage, the unit (and any resin) should be stored in a cool, dry place (15°F to 100°F). The resin itself needs to be stored in sealed and labeled containers.

Ways to Keep Your Business Going in the Winter

Professional window cleaners can offer a range of services during the winter months when regular outdoor window cleaning schedules may be on hold. Here are some services that you can consider providing in winter:

• Interior Window Cleaning: Cleaning the interior side of windows is not as weather-dependent.
• High Access Cleaning: Utilizing a telescopic cleaning pole with accessories, you can perform dusting, duct cleaning, and high glass cleaning work.
• Holiday Light Hanging: Using a telescopic pole can make hanging lights inside and outside easier and faster.
• Snow Removal: Using a brush with a telescopic pole and angle adapter, you can remove snow from hard to reach entryways, roofing and such.

Protecting Your Pure Water Cleaning Investment

If you have any questions regarding the proper storage and maintenance of your pure water cleaning equipment, please contact us and we’ll be happy to discuss your specific needs.