Pour the peroxide, rubbing alcohol, dish soap and rinse aid into a spray bottle of at least a 32 oz size. Slowly add the 3 cups of water. A funnel really comes in handy for getting these liquid ingredients in your bottle without making a mess.
Put the top back on the spray bottle and then slowly tip the bottle back and forth to mix the ingredients.
If you are re-using a 32 oz bottle from a store bought daily shower cleaner spray, you can probably not even measure the water. Once you’ve added the first four ingredients, just add water to fill the bottle.
To use: After showering, mist the spray on the walls of the shower and you’re done. There’s no need to wipe.
One final note: Hydrogen peroxide can slowly break down in the light. That’s why hydrogen peroxide is always sold in those dark brown bottles. If possible, keep this mixture in a cupboard or some other place where it will be dark to keep the hydrogen peroxide at optimum performance.
A couple other ideas are to use a dark bottle, or to just add a little more peroxide from time to time.