How to Get Stains Out of Grout
Grout stains fall into two main categories: surface stains from dirt and spills (which are relatively easy to remove), and mildew or biological growth embedded in the grout (which requires more targeted treatment). Grout is porous, which makes it absorb staining compounds readily — regular cleaning and sealing are the most effective long-term strategies.
Baking Soda and Vinegar (Light to Moderate Stains)
Apply a paste of baking soda and water directly to the grout lines. Spray or pour white vinegar over the paste — the fizzing reaction helps lift dirt and light biological growth from the porous surface. Let it sit for 5–10 minutes, then scrub vigorously with a stiff-bristled grout brush or old toothbrush. Rinse with water. This method is safe for all grout and tile types.
Hydrogen Peroxide (Mildew and Dark Stains)
For grout that has turned grey or black from mildew, apply undiluted 3% hydrogen peroxide (available at any pharmacy) directly to the grout lines. Let it sit for 10–15 minutes without scrubbing — the peroxide oxidizes the mildew and discolouration. Scrub with a grout brush, then rinse. For stubborn cases, make a paste of hydrogen peroxide and baking soda for extended contact time.
Oxygen Bleach (Heavy Staining)
OxiClean or generic oxygen bleach (sodium percarbonate) dissolved in warm water is highly effective for heavily stained grout. Apply with a brush, work into the grout lines, and let sit for 15–30 minutes. Oxygen bleach is safer than chlorine bleach for coloured grout and surrounding tile, and does not produce harsh fumes. Rinse thoroughly.
Chlorine Bleach (White Grout Only)
For white grout with severe mildew, chlorine bleach gel applied with a grout brush is the most aggressive option. Use in a ventilated area, avoid contact with coloured or natural stone tiles (it can bleach or etch them), and rinse completely. Only use this as a last resort.
Sealing Grout After Cleaning
Once clean and fully dry, apply a penetrating grout sealer. Sealed grout is non-porous — stains sit on the surface rather than absorbing in, making future cleaning significantly easier. Reapply annually in shower areas, every 2–3 years on floor tile.
Professional Deep Clean in Toronto
Maidless Toronto deep cleaning includes grout scrubbing in kitchens and bathrooms. Book at maidless.ca.