How to Fix a Leak Through the Bathroom Floor

Make a cut into the caulk at one corner of the grout with a utility knife, large enough to accommodate the tip of a flat screwdriver. Insert the tip of the screwdriver into the cut and wedge it into the caulk strip until it breaks. Slowly move the screwdriver along the line of caulk until it breaks. Continue to remove the caulk line between the floor and adjacent wall.

Position the tip of the screwdriver over the grout between two floor tiles at a corner of the bathroom floor. Pound the screwdriver handle with a hammer so it cuts through the grout and forms a small hole. Insert the tip of the screwdriver into this hole, angle it slightly upward and pound it again to remove a small section of the grout. Continue this process to remove the grout between the tiles where the floor typically leaks.

Brush away the broken grout from the floor with a hard-bristled brush, or use a vacuum cleaner for a large area. Insert a wet rag into the gaps between tiles to remove tiny leftover pieces of grout. Allow the floor to dry completely.

Prepare a batch of grout according to its packaging directions. Adhere to the specified grout-to-water ratio so you produce the appropriate consistency, especially since the grout you prepared the first time was incorrect and is causing the floor to leak.

Scoop up some grout and apply it over the tiled floor you are working on using a trowel. Hold the trowel at a 45-degree angle and press the grout into the spaces between the tiles until they are filled. Wipe away excess grout from the surface of the tiles using a wet sponge. Allow the grout to dry for 24 hours.

Apply a bead of silicone caulk into the edges of the floor and against fixtures. Allow the caulk to cure for the time specified on its packaging directions.

Apply a sealant over the caulk and grout with a paintbrush. Allow the sealant to dry before using the bathroom.