Reverse osmosis filters have a huge range of sizing and water filtering functions. Get single replacement RO filters and only change the water filters that need changing. You can always save yourself the hassle of finding individual RO filters and get a reverse osmosis filter set instead.
Reverse Osmosis Water Filter Types
Refrigerator Filters - these are inline with your refrigerator. This is an easy to use filter that needs to be change every 6 months.
Under sink water filters - These are plumbed next to your kitchen faucet and provide clean water on tap. These systems are the most common in homes and considered a standard RO system for home drinking water.
Multi-stage water filters - These are usually a multi part filter system which may have three different filters. These are usually pumped systems so they need an electricity supply. Sand or gravel filter that removes organic matter, then a charcoal filter cleans larger particles as well as taste and odor, and another filter that removes micro-organisms. A refinement to this type of filter is a UV (Ultra Violet) filter that kills microbiological organisms.
Whole House Water filter systems - they're more expensive and many whole house water systems are designed specifically for your home's water type, whether it's well water or city water. They require pretreatment, delivery pumps, and water storage tanks.