A water filter is a part of treating water to remove particles. The size of the filter will determine what it can eliminate, which can range from bacteria to viruses to tiny, undissolved substances. Various filter technologies are available, including reverse osmosis, which can filter up to 0.0005 microns of impurities.
You can also select from water filtration products, such as standalone dispensers that sit on your benchtop or stand on the floor. If you prefer cleaner water for your entire home, you need a whole house filtration system. It's designed to make your water more palatable and sterile for drinking and other uses.