Pure Water Window Cleaning, Explained: Why Spot-Free Works
Pure water window cleaning lets you clean glass from the ground with a brush and a pole — no ladders, no squeegee, no detergent — and the glass dries spot-free. The trick is in the water. Here's what's actually happening.
What "Pure" Water Means
Tap water carries dissolved minerals (the "TDS" — total dissolved solids) that leave spots when water dries. A purification system strips those minerals out using reverse osmosis and/or deionizing (DI) resin, leaving water with a near-zero TDS reading. That water dries clean because there's nothing left in it to leave behind.
RO/DI vs. DI-Only
DI-only systems run tap water straight through resin — simple, but the resin gets used up fast in hard-water areas. RO/DI systems use a membrane to remove most of the minerals first, so the resin lasts far longer. If you're in a hard-water region, RO/DI usually wins on running cost.
Watch Your TDS Meter
A TDS meter is the cheapest insurance in this trade. Check your output regularly — when it starts climbing toward 10 ppm, your resin is spent and you'll start seeing spots. Swap or recharge before it costs you a callback.
Building a System
We stock pure-water systems, resin, membranes, and TDS meters from Pure Water Power. Tell us your water hardness and how many gallons a day you run, and we'll help you size a system that won't burn through resin.