How to Regrout Bathroom Tile

Grout fails. Water seeps behind tile, mildew spreads, and those white lines between your bathroom tiles turn dark and crumbly. The thing is, you don't have to tear out tile to fix it. Regrouting is one of those repairs that looks intimidating until you actually hold the tools—then it becomes straightforward work that anyone with a steady hand can handle. What separates a good regrout from a sloppy one is patience: getting the old grout completely out, keeping your new grout at the right consistency, and resisting the urge to rush the cure time. This guide covers the bathroom wall tile and floor tile you see most often—glazed ceramic or porcelain in small to medium formats. Larger format tiles, natural stone, or wet areas like shower pans have different techniques, but the fundamental process stays the same. You're removing a failed sealant and replacing it with a new one. Budget a weekend for a typical bathroom and plan to avoid using the space for at least 24 hours after you finish.

1. Spot Damage and Clear Space. Walk the bathroom and determine which grout lines need attention. If it's surface discoloration only, you may just need cleaning, not regrouting. Look for soft, crumbly grout that crumbles when you push on it with a putty knife, or gaps wider than 1/8 inch. Clear the bathroom of personal items, remove soap dispensers and towel bars, and lay plastic sheeting on the floor to catch grout dust. Open a window or set up a fan; grout removal creates fine, talcum-like dust that will settle everywhere for days if you don't ventilate.
2. Excavate Every Joint Thoroughly. A rotary tool with a grout blade cuts fastest and works well on smaller bathrooms. Hold it at a slight angle to the joint and move steadily along the line; the blade should sit centered in the grout joint. For large areas or if you don't have a rotary tool, a manual grout saw (also called a grout rake) works fine—it's just slower. Go deep enough to remove all the old grout, typically 1/2 to 3/4 inch down. You want the joint completely clear and loose debris easy to vacuum out. If you hit tile and it chips, ease up; the grout came out, so keep moving. Wear a dust mask rated N95 or better.
3. Eliminate Every Speck of Dust. Use a shop vacuum fitted with a fine-dust filter to pull out all the loose material from the joints. Go over each line more than once—dust sits in the bottom of the joint and affects new grout adhesion. Pay special attention to horizontal lines where dust settles naturally. A hand vacuum or even a stiff brush followed by a damp cloth works on small areas, but a shop vac is faster and more thorough. After vacuuming, wipe the entire tiled surface with a damp sponge to settle any remaining dust and rinse the joints.
4. Guard Woodwork and Fixtures. Mask off baseboards, wood trim, and any painted surfaces adjacent to the tile with painter's tape. Caulk (not grout) any joints where tile meets tub rims, fixtures, or corners—these areas need flexibility that grout doesn't provide. If you haven't already, lay plastic sheeting on the floor and ensure the room is well-ventilated. Close interior doors to contain dust.
5. Achieve Peanut Butter Perfection. Pour dry grout into a bucket and add water gradually, stirring constantly with a power drill fitted with a paddle mixer. The goal is a thick, peanut-butter consistency that holds peaks when you lift the mixer but still flows into joints. Too thick and it won't pack down; too thin and it shrinks away from the tile edges as it dries. Start with less water than you think you need and add more in small amounts. Mix only the amount you can apply in 20 to 30 minutes—leftover grout hardens in the bucket and you can't rehydrate it. Most small bathrooms use one bag of premixed grout, but read the bag for specifics.
6. Force Grout Deep Into Joints. Load grout onto a grout float (a rectangular trowel with angled edges) and press it into the joints at a 45-degree angle, working diagonally across the tile. This angle forces grout down into the joint rather than just spreading it across the surface. Work in sections about 3 by 3 feet. Pack the grout firmly so it fills the entire joint depth with no voids or air pockets. Use the flat edge of the float for the final pass, which settles the grout level with the tile surface. Don't worry about cleanup yet; you'll do that in the next steps.
7. Wait for the Magic Firmness Window. Set a timer. Grout needs 20 to 30 minutes to firm up (this varies by grout type and humidity). If you clean too early, you'll pull grout out of the joints. If you wait too long, the grout hardens and becomes much harder to clean. When the time is up, test a corner: press your finger lightly into a joint. If it holds the impression but doesn't stick to your finger, you're ready.
8. Wipe Without Weakening. Use a large grout sponge (denser than a regular sponge) dampened with cool water. Wring it thoroughly so it's moist but not dripping. Work diagonally across the tile in small circles, rinsing the sponge frequently in clean water. You're removing the haze and excess grout on the tile surface while leaving the joint full and smooth. The grout will still be slightly soft, so don't dig into the joints. After the initial cleanup, let it set for another 30 minutes, then do a final light cleanup pass with a barely damp sponge to remove any remaining haze.
9. Keep Water Out for Two Days. Do not use the shower or splash water on the regrouted area for at least 24 hours, preferably 48 hours. Grout cures by hydration and evaporation; rushing this step causes it to stay weak and crumbly. Ensure the room stays above 50°F and below 85°F during cure time. High humidity actually helps grout cure (it needs moisture), so don't run the exhaust fan constantly. Light ventilation is fine, but don't set up fans blowing directly on fresh grout.
10. Lock in Protection Forever. After the grout has cured for the full 48 hours (or the time specified on the sealer bottle), apply a penetrating grout sealer according to the product instructions. Most sealers are applied with a small brush, bottle applicator, or spray. The sealer fills the pores in the grout and prevents water and stains from soaking in. This step is critical in bathrooms where grout is regularly exposed to moisture. Reapply sealer every 1 to 3 years depending on use and the sealer type.
11. Fill Any Last Gaps. Once fully cured and sealed, walk the bathroom and look for any thin grout lines where the joint shows gaps or the grout didn't fully pack. If you find small voids, mix a small batch of grout (just a cup or two) and carefully pack it into the thin spots with the tip of your grout float or even a putty knife. This is common where tiles meet at corners or where you had to work around fixtures. One or two touch-up batches is normal and expected.