Reviewed and recommended: Aquasana shower filter
I started to research shower filtering systems and settled on Aquasana. It comes with a refill filter and the consensus seems to be that each filter lasts about six months (assuming normal, once a day showering habits)
This isn't just about hard water. Did you realize, for example, that there is more chlorine in tap water than in most swimming pools. Chlorine is horrible for hair and, for that matter, skin.
The Aquasana (pictured below) has a two-stage filter system. The first removes chlorine and restores the PH balance with a copper/zinc mineral formula. The second stage uses carbonized coconut shell to filter chemicals.
I installed it at our house in the Catskills. Our water comes from a spring via the 400ft well that we had dug. I've always found this water dry and chalky and find my skin, hair and nails get very dry up here. The Aquasana Shower Filter is transforming. The hairbrush glides through my hair after a shower (no more dry tangles) and my skin feels so soft that I am tempted to skip body lotion.