Another good alternative to remove dirt from shower tile grout is white vinegar. Here’s how to use it:

Prepare a solution of vinegar and warm water
Pour the liquid into a nebulizer and spray directly on the areas
to be treated Leave to soak
for 10/15 minutes Rinse with a
damp cloth The product can also be used effectively against mold and all types of dirt that have accumulated between the joints of bathroom tiles.

Clean grout with
potato starch Potato starch is effective against black spots and also works against the most stubborn dirt. To prepare a perfect solution to remove black spots, you need to mix 1 tablespoon of starch with 1 liter of warm water and put the mixture in a spray bottle.

Spray the product obtained between the joints, leave it to act for about half an hour, then remove the encrusted dirt with a clean, damp cloth.