I’ve written about how easy and money-saving it is to wash shower curtains and liners in the washing machine, which does a good job of removing mildew, mold (I can’t tell which is which), soap scum, and the dreaded serratia marcescens bacteria. Then I got to to thinking: if only there were a way of preventing those gross nasty things!
Some sort of shower spray would probably do the trick. A DIY homemade shower spray would probably be cheaper than a special store-bought product.
Several websites have recipes for homemade shower cleaners 
that include ingredients such as vinegar, rubbing alcohol, hydrogen peroxide, among other things, mixed with water. I decided to start with plain vinegar, mainly because it’s the least expensive. Costco sells a jug of vinegar, more than gallon, for about $3. Regular (sometimes called white) vinegar is usually 5% acidity. Cleaning vinegar (which isn’t intended for food use) is usually 6% acidity. So far, I’ve been using the 5% food-safe vinegar, mainly because it’s more readily available.
All I do is fill a spray bottle with plain straight vinegar. Once or twice a week I give the bathtub and shower area a thorough spray. I usually do it after I take a shower and when I’m sure no one else will take a shower for the next several hours. Before I spray, I give the shower curtains a quick shake to remove most of the clinging water droplets — I don’t want my vinegar spray to be diluted as soon as it’s applied. I spray the entire tub area, the walls, both sides of the shower curtains and liner, paying particular attention to areas where I’ve seen mildew and mold in the past, which tend to be the corners and lower parts of the shower curtain, liner, and tub walls. Then I just leave it alone. I assume that prolonged contact with vinegar is bad for mildew and mold, which is good for me.
So far it’s working, and it’s cheap. The only disadvantage is the smell of vinegar, which can be overpowering in an enclosed space (remember, bathroom ventilation is important), but I can put up with that for a few minutes each week. You might want to wear rubber gloves, because contact with vinegar isn’t good for your skin.
