Three types of water purifiers.

1) Countertop water purifier – This type of water purifier is typically installed under the kitchen sink or on a countertop. It is typically used in homes with smaller families and doesn't need to produce a lot of purified water at one time.
2) Whole house filtration system – This type of water purifier can be installed in the basement or crawl space and filters all the water that comes into your home. It is ideal for larger families or anyone who wants to have peace of mind knowing their entire home’s drinking water is purified.
3) Point-of-use (POU) system – These systems have many different names, such as faucet-mounted, under-counter, or countertop filters. They filter only the water that goes directly through them so they are great for people who want to drink filtered tap water but don't want to bother