Reverse osmosis at a shower is a request that comes up regularly and is almost never the right answer, for a reason that is purely physical rather than a matter of cost. Membranes produce slowly, and a shower is the highest sustained draw in most houses. The complaints behind the question are real, and there is equipment for each of them.
The arithmetic does not work
An under sink membrane produces a few gallons a day into a storage tank, which is ample for drinking and cooking and nothing like a shower's demand. To supply a shower on demand you need many times the membrane area, a large atmospheric tank and a repressurisation pump, which is a point of entry system serving the whole house rather than a shower fitting. And every gallon produced sends a concentrate stream to drain, so the water use for showering this way is considerable.
What the complaints usually are
Two things send people looking. Chlorine, noticed as a smell in the steam and a tight, dry feeling on skin and hair afterwards. And hardness, noticed as scale on the screen and head, spotting, and soap that will not rinse away. Those have different answers and neither of them is a membrane. Being clear which one you have takes a minute: your utility's annual report names the disinfectant and states hardness.
The equipment that does address them
For chlorine, a shower filter containing KDF or calcium sulfite reduces it at the fixture, or a point of entry carbon filter removes it from every tap and shower at once, which is usually better value if more than one bathroom is involved. On a chloraminated supply, media based devices do much less and ascorbic acid products are the ones that work. For hardness, an ion exchange softener treating the whole house is the only thing that removes it, and it is what changes the shower experience.
Where whole house membrane treatment is justified
There is a case, and it is narrow: source water genuinely unusable throughout the house, such as brackish groundwater or very high dissolved solids, where bathing and laundry are affected and not only drinking. That is a designed point of entry system with pretreatment, storage, repressurisation and remineralization, because demineralized water is aggressive to plumbing. It is not a shower upgrade. Our whole house reverse osmosis guide covers what that installation involves.
Questions people ask about reverse osmosis for shower
Can I put a reverse osmosis filter on my shower?
Not practically. Membranes produce slowly into a tank, and a shower is the highest sustained draw in most houses.
What helps with chlorine in the shower?
A shower filter with KDF or calcium sulfite, or a point of entry carbon filter that treats every tap and shower at once.
What helps with the hard water feeling?
Only a softener, which removes the hardness minerals from the whole supply. No shower fitting does that.
Is whole house reverse osmosis ever justified?
Where the source water is unusable throughout the house, such as brackish groundwater. It is a designed system, not a shower upgrade.