Mix the baking soda and bleach together in the bowl until it forms a thick paste.
Apply the paste to the dirty grout lines and let it sit for 15 minutes.
Scrub the paste into the grout lines with a scrub brush, ensuring it covers the grout lines entirely.
Let the paste sit for at least another 15 minutes.
Rinse the paste off of your tile and grout with clean water and a rag.
