What is the Difference Between a Water Filter and a Water Purifier

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What is the difference between a water filter and water purifier? Flickr Commons image via Rick Cogley

We talk a lot about water filtration and water purification systems here and for the most part it is safe to say we “unpack” what we mean pretty well. 

However, since the topic of what grows in your water deals in minutiae (either in the form of microorganisms, minerals that may or may not be detectable to the naked eye, or the technology involved in improving water), I would like to go ahead and add the minutiae of semantics as we define some terms a bit further.

Specifically, what exactly do the terms “filter” and “purification” have in common and how do they differ? 

The Difference in Definition

To “filter” is defined by Webster’s dictionary as “to pass or move through or as if through a filter.” Another definition reads “the separating of substances based on their different physical and chemical qualities...” The definition of “purity” in Miriam-Webster’s Dictionary however says “...to clear from material defilement or imperfection”. 

Water Filter

The term “water filter” generally refers to a device that uses a physical means by which particles are prevented from passing into the final destination of the water. 

Often times this involves a porous material which traps unwanted particulate.

A filter most often consists of an activated carbon, catalytic carbon or ion exchange system. These filters can do quite a lot to improve water and are the easiest and cheapest to use.

Water Purification 

On the other hand, the term “water ‘purification’ system” usually indicates a system that effectively renders the water almost free of ANY contaminants. 

The primary types of systems designed to effectually leave your water “purified” are Reverse Osmosis (RO) and Distillation; although by the standard of removing viruses ultraviolet (UV) light systems are also essentially purifying the water they treat. The distinction here being that in the world of water, a “purifier” removes a minimum of 90% of impurities and does not stop at taking care of actual particulate but also removes chemicals dissolved into the water as well as viruses (the smallest biological contaminates). 

Conversely a “filter” sifts out the biggest kinds of contaminates and takes water to a higher baseline quality than completely untreated water. 


In conclusion, filters can be great!

They are easily obtained and can be put to good use in just about any household requiring little to no installation. They're also inexpensive and operate relatively simply while also effectively. However, the conscientious homeowner should not be lulled into a false sense of security and stop at water filtration.

Many harmful metals, minerals and chemicals are unstoppable by a simple water filter and require the more targeted, thorough approach of an actual purification system designed to nearly eliminate all contaminants from water resulting in the best quality, safest and most healthful water for human consumption.

Good luck on your quest for clean water. To tweak a common idiom “May you get all the good and none of the bad.” 

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