Water contains a lot of bacteria, viruses, and contaminants. Tap water usually needs a filter of some kind to make the water safe to drink. Most filters, like pitchers and under the sink systems can remove some toxins, but leave many still in the water. They can filter the water, but they do not purify it. For water to be considered purified, it must be free of most bacteria, viruses, contaminants, heavy metals, pesticides, and chlorine. Trace elements may remain, but purified water is the clearest water you can drink. Many filters do not come close to purifying water.
Ozonation is a process that uses oxygen to kill most of the contaminants in water. It breaks down the organic chemicals, so very little bacteria remains. The problem with this type of system is that it can also create byproducts, such as formaldehyde, if not controlled properly. It cannot work without electricity, so the benefits are lost if the power goes out. It filters better than most pitchers and basic systems, but is cannot be considered a water purifier.
The best water purifier uses various media types in the filtration process. That way, the most contaminants are absorbed from the water. The process is effective in removing viruses, bacteria, and chlorine. It does not remove natural minerals from the water. This system is affordable to purchase, and easy to maintain. Filters are changed only once a year. This Berkey water filter is considered a water purifier because it removes the most amount of contaminants from your drinking water. There are a few drawbacks to the system. You cannot have it placed under your sink, like you can with reverse osmosis systems. It has to be placed on your counter. There are different sizes, so you can find one that will fit in the space you have available in your kitchen.
When you look at the berkey water filter vs reverse osmosis, the benefits are obvious. Reverse osmosis uses four or five steps to filter your water, and takes a long time to do it. That system uses electricity, so it cannot work in an emergency if the power has gone out. The Berkey filter needs no electricity. It is also available in portable sizes, so you can use it to purify river and lake water if you are camping.