Quick take
Point-of-use treatment can cost under a few hundred dollars. Whole-house catalytic-carbon systems usually cost around the low four figures or more before installation because chloramine needs sufficient media and contact time.
Point-of-use cost
An under-sink carbon or RO system can be the economical choice when the concern is drinking-water taste or chemistry at one faucet.
Whole-house catalytic carbon
Treating showers, laundry and every faucet requires much larger media beds and adequate service flow, which raises hardware cost.
Why cheap undersized tanks can disappoint
Chloramine reduction is sensitive to contact time. Buying only by the lowest price can produce poor performance at real household flow.
Confirm chloramine first
Check the utility report before paying a premium for catalytic carbon if the system actually uses free chlorine.