Quick take
For a refrigerator ice maker, start with the correct OEM or validated compatible cartridge. For standalone ice makers, carbon filtration is often enough unless hardness or broader contaminants justify RO.
Refrigerator ice makers
Use the exact filter specified for the refrigerator or a compatible cartridge with verified fit and appropriate certification.
Standalone ice makers
A dedicated inline or under-sink carbon filter can improve chlorine taste and capture sediment before the appliance.
Hard water and scale
Hard water can create mineral deposits in ice-making equipment. RO can reduce scale-forming minerals when appliance maintenance is a recurring problem.