Article originally sourced from: Evewoman
"Grout is the material used in between tiles to prevent water from seeping under them. Modern-day flooring uses lighter-coloured grout which quickly absorbs oils, dust, detergents and becomes a filthy eyesore. While it is easy to clean tiles, cleaning grout is not easy.
Here are a few ways to get that grout sparkling again.
Fresh lemon juice is a powerful natural lightener and can be used to give life to dirty grout. You will however have to use lemon regularly to achieve impeccable tiles. You can further mix lemon with baking powder to form a cleaning paste.
The name sounds like a rare potent chemical but you can buy borax from your local agro store. It is a naturally occurring element. To use borax for cleaning grout, apply it on the grout with a damp microfiber or cotton cloth. Leave it for some hours, even overnight. In the morning, scrub down the grout and rinse with warm water to reveal new grout lines.
Vinegar plus baking powder paste
Make a paste of distilled white vinegar and some baking powder. Apply the paste on the grout as well as tiles and let it sit overnight. If you are working on a floor you can cover the floor with a plastic sheet. On the next day scrub the grout with a hard toothbrush until sparkling clean then rinse with warm water.
Hairdressers use hydrogen peroxide to bleach hair and you can use the same to clean out grout. Hydrogen will not only clean the grout but it will also disinfect them and prevent growth of mold and bacteria. Mix peroxide with white flour until you get a paste. Apply the paste onto the grout and let it stay overnight. In the morning, scrub the paste off and reveal your clean sparkly grout."