It's not uncommon for mould to form on the caulk surrounding a bathtub. This mould can generally be cleaned up with a simple mixture of bleach and water. However, when the mould keeps coming back over and over again, it's important to look a little deeper and identify the cause. There are several possible reasons why mould may keep appearing on your caulk, and below, you will learn how to fix them.

The caulk is starting to peel away from the tub.

Take a careful look at your caulk. Are there any areas where it seems to be peeling away from the tub's surface? If so, the water may be seeping behind the caulk and allowing mould to form on the backside of the caulk. This mould is hard to reach with your bleach water, so it stays intact, and a few days after you bleach the outer surface of the caulk, it creeps back out.

To fix this problem, you'll need to use a putty knife to peel all of the existing caulk away. Wipe the area down with a bleach and water mixture to ensure any remaining mould is killed. Then, let the tub completely dry out for about 2 - 3 days. This will ensure that any moisture in the groove where the tub meets the wall has a chance to evaporate.

After your drying time has passed, apply a new layer of caulk to the tub. Make sure you only apply a very thin strip of caulk; many people apply too much caulk, and this encourages it to peel away from the edge of the tub. Use your finger to smooth the caulk after you've squeezed it out along the seam. Let the caulk dry for at least 2 days before using the tub.

Water is pooling in the groove of the caulk after you bathe.

If your caulk appears to be in good shape and is not peeling away from the wall, your caulk is probably getting mouldy because water is pooling on top of it when you bathe and not getting the chance to dry up completely. If enough water pools on top of the caulk, it will stay moist day-in and day-out, making it a great place for mould to grow.

Take a shower or bath (whichever you normally do) and then observe how your tub dries over the next day or so. Are there areas where the caulk is still wet, hours later, even after the rest of the tub has dried? Dry these areas off, let them air dry for a day or so, and then apply a second thin layer of caulk on top of the caulk that's already in these areas. This will rise the level of the caulk in these areas, so the water drains off more effectively.

If mould is appearing on your caulk, don't ignore the issue. You'll either need to replace the caulk or build up the caulk in certain areas to eliminate moisture and solve the problem permanently. If this doesn't solve the problem, you may have a bigger mould issue on your hands. You may need to call in help, such as mould remediation services from Clean Air Services Inc.