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Why It’s a Good Idea to Change Your Water Filters


by Rick Andrew, Global Business Development, NSF International

Wouldn’t it be wonderful if every tool and product we bought required absolutely no maintenance and it would work forever? It absolutely would! And while today’s designers and engineers continually work to reduce and simplify the maintenance that we need to perform on all of life’s wonderful gadgets and devices, it is unlikely that maintenance will ever be eliminated. At some point, batteries need to be charged or even changed, systems need to be upgraded, fluids need to be changed, and… filters need to be changed.

No matter what kind of filter, it needs some type of maintenance. Oil filters in automobiles, furnace filters, and yes, the filters in your household water treatment system. One reason for filters needing to be changed is obvious – eventually, filters become clogged. Once they are clogged, then oil, or air, or water does not flow through, at least not easily.

But there is another important reason to change water filters. This one has to do with the functionality of the activated carbon inside them. The activated carbon uses a process called, “adsorption” to attract certain contaminants and reduce their concentrations in water. As the carbon adsorbs more and more of these contaminants, it eventually becomes saturated. And once it is saturated, it will no longer function correctly.

It is important to understand this, because saturation of the activated carbon will not be obvious in any way. This is why it is so important to follow the manufacturer’s instructions regarding replacement frequency. Although it may not be obvious, the filter may no longer be performing its intended function until it is replaced.

By the way, as a side note, the testing and certification of these filters under the NSF/ANSI standards for reduction of contaminants requires that the end point of the testing be based on the manufacturer’s recommended replacement frequency. So, for filters certified by NSF International, you can rest assured that the filter will function as advertised throughout the manufacturer’s recommended life.

Rick Andrew is the Global Business Development Director for NSF International’s Water Programs. He has previously served as General Manager, Operations Manager and Technical Manager for NSF’s Drinking Water Treatment Units (POU/POE) Program. Andrew has a Bachelor’s Degree in chemistry and an MBA from the University of Michigan. He can be reached at (800) NSF-MARK or

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