Grout is porous and collects dirt, soap scum, and mould over time. Scrubbing with a toothbrush gets results but takes forever. Here are methods that do more of the work for you.
Method 1: Baking Soda + Hydrogen Peroxide Paste (Best All-Rounder)
- Mix baking soda and hydrogen peroxide into a thick paste — roughly 2 parts baking soda to 1 part hydrogen peroxide
- Apply the paste along the grout lines with an old toothbrush or small brush
- Leave for 10–15 minutes
- Scrub lightly — the peroxide does most of the lifting, so you need much less force than dry scrubbing
- Rinse with warm water
This works well on most grout discolouration and light mould.
Method 2: Oxygen Bleach Soak (Best for Floor Grout)
- Mix oxygen bleach powder (like OxiClean) with hot water according to package directions
- Pour or spray liberally over the tile and grout
- Leave for 15–30 minutes — the longer, the better
- Mop or wipe away — most dirt lifts without scrubbing
- Rinse thoroughly
Oxygen bleach is colour-safe and won't damage coloured grout. Do not use chlorine bleach on coloured grout — it strips pigment.
Method 3: Steam Cleaner
A handheld steam cleaner with a narrow nozzle attachment blasts grout lines with high-pressure steam that loosens dirt and kills mould without any chemicals. Run the nozzle along the grout line and wipe immediately with a cloth. This is the fastest method for large tile areas like shower walls and bathroom floors.
Method 4: Commercial Grout Cleaner
Products like Zep Grout Cleaner or Black Diamond Grout Cleaner contain mild acids that dissolve mineral deposits and soap scum. Apply, wait, and rinse. Good for heavily soiled grout that hasn't been cleaned in a long time. Follow product directions for dwell time.
Preventing Grout From Getting Dirty
- Seal grout annually — a grout sealer fills the pores and makes it much easier to wipe clean
- Squeegee shower walls after every use to reduce soap scum build-up
- Run the bathroom fan during and for 15 minutes after showers to reduce humidity