Most walls in the average house are painted, and paint likes gentle cleaners, such as water. Harsh cleaners can dull gloss or semi-gloss finishes, and, if the walls are painted with a flat paint, the cleansers can literally strip it from the walls. You usually need to add something to the water to emulsify dirt and grease, though, or you'll end up scrubbing too hard, which can also damage paint. An all-purpose cleaner should also contain a disinfectant. A good disinfecting cleaner for painted walls can handle vinyl, metal or tiled walls, too.
Vinegar -- If you had to reduce your cleaning arsenal to just five compounds, vinegar would have to be one of them. This tangy condiment contains acetic acid, which makes it useful for myriad household chores, and it's safe; if it weren't, you'd never put it on your food. Lemon juice is comparably acidic and just as useful.
Soap -- Soap is not detergent; it isn't synthetic, it biodegrades easily, and it's safer to use. A disadvantage of soap, however, is that it reacts with minerals and leaves a film.
Borax -- A mineral that comes straight out of the ground, borax -- or sodium borate -- cleans, deodorizes and disinfects.
Baking soda -- A well-known deodorizer, sodium bicarbonate also disinfects, and its mild abrasive action is good for scrubbing.
To make a nontoxic, all-purpose wall cleaner, start with a gallon of warm water and add an ounce of dish or Castile soap to emulsify dirt and grease and make it easier to remove. Pour 1/2 cup of vinegar into this solution to add a disinfectant; if you expect to be cleaning walls with white mineral streaks, double that amount. Finally, add an ounce of isopropyl alcohol for enhanced stain-removal power.
Soak a sponge or rag in the cleaner and wring it out thoroughly.
Wipe stains, dirt, mold, crayon marks and grease, dipping the sponge in the solution as needed.
Add scouring power for difficult-to-remove stains by sprinkling baking soda or borax on the sponge after you dip it in the cleaner and wring it out. Scrub the spots; then wipe the wall with the cleaner after scrubbing.