Grout is porous, slightly textured, and runs through every tiled surface in your home — which makes it one of the hardest surfaces to keep clean. Discoloured, stained, or mouldy grout makes an otherwise clean bathroom or kitchen look neglected. The good news: with the right approach, most grout can be restored without professional intervention.
Why Grout Gets Dirty
Grout is made from a mix of cement, sand, and water — which gives it a porous structure that absorbs water, soap residue, and dirt. In bathrooms, humidity accelerates mould growth in grout joints. In kitchens, grease and cooking residue penetrate and stain. The finish coat (sealant) on new grout helps, but it wears off over time and must be reapplied to maintain protection.
Cleaning Methods by Stain Type
Surface dirt and soap scum (most common)
A paste of baking soda and water applied to grout lines, scrubbed with a stiff-bristle brush, and rinsed removes most surface discolouration. Apply the paste, let sit for 5 minutes, scrub in a circular motion, and rinse thoroughly. For bathroom grout near the shower, this method handles 80% of typical buildup.
Mould and mildew (black or green spots in grout)
Mix equal parts water and white vinegar in a spray bottle. Apply directly to affected grout lines and let sit for 10–15 minutes. Scrub with a stiff brush and rinse. For more stubborn mould, hydrogen peroxide (3% solution, available at any pharmacy) is more effective than vinegar — apply, let sit 10 minutes, scrub, rinse. For severe mould that has penetrated the grout, a diluted bleach solution (1 part bleach to 10 parts water) is the strongest DIY option, but ventilate well and rinse thoroughly.
Grease stains in kitchen grout
Dish soap and hot water is the starting point. Apply a generous amount of dish soap directly to the grout, work it in with a brush, and let sit for a few minutes. For baked-on grease near the stove, an enzyme-based degreaser is more effective. Apply and let sit for 5–10 minutes before scrubbing.
Tools That Make a Difference
- Stiff-bristle grout brush — a narrow, stiff brush designed for grout lines. Much more effective than a cloth or standard scrub pad.
- Electric scrubber — for large-area grout cleaning, a battery-powered scrub brush significantly reduces effort.
- Steam cleaner — high-temperature steam dissolves mould, grease, and mineral deposits without chemicals. Works very well on grout. The standard choice for professional deep cleans.
Sealing Grout After Cleaning
Once grout is clean and fully dry (allow 24–48 hours), apply a penetrating grout sealer. This fills the porous structure of the grout and makes future cleaning significantly easier — water and soap bead rather than absorbing. Reapply annually in bathrooms, every 1–2 years in lower-traffic areas.
When to Call a Professional
If grout has years of buildup, deep mould penetration, or surface damage (cracking, crumbling), DIY methods have limits. Professional deep cleaning uses commercial-grade equipment and appropriate products for the tile type. Maidless includes grout scrubbing as part of our deep cleaning service in Toronto and across the GTA. Book a deep clean online with HST included.