Baking soda and hydrogen peroxide made into a paste. Scrub grout lines with a stiff brush and rinse.
What You’ll Need
1/4cupBaking soda
1/4cupHydrogen peroxide
(Lighter method) 1 cup Hot water and 1 cup White vinegar
Scrub brush (stiff, not metal)spray bottle; grout sealer (optional)
Directions
Stir equal parts baking soda and hydrogen peroxide (1/4 cup each) into a paste.
Spread it over the grout and leave for about an hour.
Scrub with a stiff brush.
Wipe up with a damp cloth or mop, rinsing away any residue.
For lighter cleaning: spray the grout with hot water or equal parts hot water and vinegar, wait 5-10 minutes, then scrub and rinse.
Optional: let the grout dry for at least overnight (up to 24 hours), then seal it.
Notes
Mix the peroxide paste fresh; don't store it. Safety: skip chlorine bleach, it can permanently discolor grout and tile. Also: never mix vinegar and bleach; don't use vinegar on natural stone (marble, travertine) or unsealed grout often; wear gloves; peroxide can lighten colored grout, test first.