Why your glasses come out of the dishwasher cloudy
Updated July 2026
Short answer: two different things are happening to your glasses. A silica film you can sometimes see through, and permanent etching caused mostly by your dishwasher's detergent working on our very soft water. Here is how to tell them apart and what actually helps.
Film or etching? The ten second check
Hold the glass under running water. A surface film changes its look when wet and comes back as it dries. Etching looks the same wet or dry, because the roughness is in the glass itself. Film also tends to be patchy while etching is a uniform haze across the whole glass.
Why soft water makes etching worse
Dishwasher detergent is strongly alkaline. In most of the country, hardness minerals in the water blunt its attack. Our water tests soft, in the single digits, so the detergent hits your glassware at full strength, cycle after hot cycle, and slowly eats the surface. Appliance makers like Miele and GE document this exact problem, and once etching starts it is permanent.
No filter prevents etching, ours included
A water system is the wrong tool for etching, no matter who sells it. What actually protects your glasses costs nothing:
Use far less detergent. In soft water a teaspoon usually does the job, and most people use several times that. Scrape instead of pre-rinsing. A little food soil actually buffers the detergent. Run cooler cycles and skip the sanitize setting and heated dry for glassware. Always use rinse aid. And hand-wash the glasses you love, because thin and older glass etches fastest.
Where reverse osmosis genuinely helps
An under-sink RO system takes the silica and dissolved minerals out of the water at your kitchen tap. Drinking water tastes clean, ice comes out clear, and glasses you rinse at that sink dry without a spot. It will not reach your dishwasher or shower, since those run on separate plumbing.