Have you ever spent hours pressure washing exterior windows, only to find streaks and water spots ruining the results? It’s frustrating. No matter how much pressure you use, no matter how careful you are, those pesky streaks seem unavoidable.

But here’s the thing—most people get exterior window cleaning completely wrong.

They’ve been led to believe that the secret lies in the perfect glass cleaner, the right cloth, or a special detergent. The truth? You don’t need chemicals. You don’t need fancy sprays. All you need is pure water—and a simple purification system to make it.

Why Tap Water is the Problem

When you use regular tap water for exterior window cleaning, you're unknowingly setting yourself up for streaks and spots. Tap water contains minerals, dissolved solids, and other impurities that stay behind when the water evaporates. This is what creates those annoying marks on the glass.

Even when you mix tap water with a cleaner, you're not eliminating these impurities—you’re just diluting them. The result? Your windows might look clean for a moment, but as soon as the water dries, streaks and spots appear like ghosts haunting your hard work.

The Science Behind Pure Water Cleaning

Now, imagine using water that has been stripped of all those minerals and impurities. Pure water. This is the real game-changer.

When water is purified through a filtration system, it becomes completely free of minerals, chemicals, and any contaminants that could leave residue behind. This means when the water dries, it leaves nothing. No streaks. No spots. Just crystal-clear glass.

Even better? Pure water is naturally aggressive when it comes to dirt. Because it doesn’t contain any dissolved minerals, it actively pulls grime, dust, and other debris off your windows. It literally absorbs dirt like a magnet—no need for soap or chemicals.

How to Get Pure Water for Exterior Window Cleaning

So, how do you get your hands on this magic water?

Professional exterior cleaning companies, like pressure washing businesses, use a water-fed pole system with a built-in purification unit. You can invest in a water purification system that removes impurities from your water before you start cleaning.

The most common systems use one or more of the following purification methods:

Carbon Filters – Remove chlorine and organic contaminants.

Reverse Osmosis (RO) – Forces water through a membrane to remove dissolved solids.

Deionization (DI) – Uses special resins to strip out remaining minerals, leaving the water 100% pure.

Once you have purified water, you can use a water-fed pole system to apply the water to exterior windows and let it air dry. No squeegees. No wiping. Just spray and walk away.

The Benefits of Chemical-Free, Pure Water Cleaning

Besides giving you streak-free windows, using pure water has a ton of advantages:

Eco-Friendly – No chemicals means no toxic runoff into the environment.

Cost-Effective – Say goodbye to expensive glass cleaners and detergents.

Safer for You & Your Property – No inhaling harsh fumes, no residue left behind.

Less Work – Forget about buffing, scrubbing, and wiping. The water does the work for you.

Perfect for Tall Windows – When used with a water-fed pole, you can clean high windows from the ground—no ladders needed.

Better for Business – As a pressure washing company, using pure water can set you apart from competitors by providing a superior, streak-free finish.

How to Clean Exterior Windows with Pure Water

Now that you know the secret, let’s walk through a simple, step-by-step process to get streak-free windows every time.

Step 1: Set Up Your Water Purification System

Install and connect your system, ensuring your water is completely purified before use.

Step 2: Pre-Rinse the Windows

Use a gentle spray from your pressure washer or water-fed pole to remove loose dirt, pollen, and debris. This prevents scratching the glass when scrubbing.

Step 3: Scrub with a Soft Brush

Because pure water lifts dirt on its own, you don’t need much elbow grease. A quick pass with a soft-bristled brush attached to your pole is enough.

Step 4: Rinse and Let Dry

Once you’ve scrubbed, rinse the window thoroughly with more pure water. Then, walk away and let it dry naturally—it will dry completely spot-free.

Final Thoughts

The idea that you need chemical cleaners to get exterior windows sparkling is one of the biggest myths in the industry. Once you start using purified water, you’ll never go back. The ease, effectiveness, and sheer satisfaction of watching windows dry to a flawless finish will change how you clean forever.

No more streaks. No more wasted time. Just pure water, pure results. And if you're looking for a pressure-washing company to help you with your exterior window cleaning. click here.