If you have tried to clean your windows with plain vinegar and gotten streaks, there is a simple reason and an easy remedy.
Oddly enough, it was the task of cleaning windows that turned a huge number of well-intentioned, environmentally friendly consumers away from non-toxic cleaning using the simple ingredients that can be found in most kitchen cupboards. Around Earth Day 1990, every newspaper in the country (or so it seemed), offered tips for cleaning in ways that didn’t harm the planet, and the recommendation for windows was almost always to clean them with nothing but vinegar and water. People by the thousands tried this, and many swore off cleaning with homemade products for good because the formula left streaks on their windows. (I wish I had $1 for every time someone has said to me, “Well, I tried non-toxic cleaning and it didn’t work. I used vinegar to clean my windows …”)
The problem was that the commercial window cleaner used before the switch to vinegar left a very fine wax residue. The vinegar alone wasn’t enough to remove it, and the result was streaky windows. If instead, everyone had added a dab of liquid dish soap to the vinegar and water, the wax would easily have been removed and the windows would have been cleaned perfectly! My favorite recipe is to combine 2 cups of water, 1/4 cup of white distilled vinegar, and up to 1/2 teaspoon of liquid soap or detergent in a spray bottle. That’s all there is to it. (Make sure to label the bottle and keep it out of the reach of children.)