There is always a concern for mold and mildew in any shower. I'll just say this, if there is water, there will be mold and mildew. But, it can be controlled by keeping you shower as clean as possible from soap scum, dirt, etc. It usually forms first under the clear caulk around the metal door frame and comes in where the grout line is located. That is because the grout line is made of portland cement and is porous, allowing water to seep under the caulk, even if it is 100% mildew resistant silicon caulk. It can also usually be found on the floor where the shower floor meets the walls. Same thing, the water gets under the caulk and starts the mold growing process and the caulk has to be removed cleaned and re-caulked.  The best way to prevent or slow this process down is to have a shower with epoxy grout. Epoxy grout is not new and has been around for ten years and has slowly be introduced to the tile world.  I was introduced to it about eight years ago and will not use anything else in walk-in showers and tub/showers. It is much messier to work with and a lot of installers resist using it, because of this. The process usually takes about twice the length of time to grout. Why do you not find more epoxy showers in the newer homes. Well, it is simply to messy to work with and it is expensive. So, the installers take the cheaper easy route. More and more customers are discovering epoxy and insisting on its use in showers as well as in the rest of the house because of the lack of maintenance needed.

But, if you have an older shower with portland cement grout, there are things we can do to prevent new mold growth. You can first get rid of the existing mold/mildew, and apply a mold guard, which has a fungicide to help prevent new growth. It has been long thought that bleach is the way to kill mold. Most mold inhibitor companies recommend soap and water and also vinegar to kill mold, not bleach.

There are a lot of web sites describing mold and mildew and here are a couple:   &