Although this may sound a little complex, we can just think of it as replacing some undesirable contaminants (like concentrations of certain minerals) with a more desirable solution.
Softening hard water, by lower concentrations of calcium and magnesium, is one common use of ion exchange for water purification.
Zerowater filters work to reduce the Total Dissolved Solids (TDS), which is one potential measure of water quality or cleanliness. TDS is typically measured in parts per million (ppm), and refers to all the inorganic substances that are suspended in water.
In fact, Zerowater jugs, pitchers and dispensers typically come with a TDS meter that you can dip into your filtered water to measure the effectiveness of the filter.
Zerowater claims that their filters can remove almost all (99.6%) of the dissolved solids impurities in your water. And they give you a meter to prove it!
What are some examples of total dissolved solids? Erosion of old piping might lead to an increase of TDS. Similarly, runoff of pesticides and fertilizers by agricultural operations can increase the TDS in surrounding groundwater.
Zerowater filters also remove lead up to U.S. EPA standards, which allow a maximum of 15 parts per billion (ppb) in drinkable tap water.
Read: Our full in-depth review of ZeroWater filters.
How Long Do ZeroWater Filters Actually Last?
So we know that Zerowater filters use ion exchange to reduce the TDS in our drinking water. Sounds great. But a big part of deciding whether to invest in a water filter is getting an estimate of costs down the road.
The biggest question is usually: how often will I need to replace my filter? Switching out an old filter for a new one once in a while seems manageable, but doing it too often can really make the costs add up.
Unfortunately, there’s no single answer to this question, as frequency of filter change will depend on how hard the filter is working (the amount of dissolved solids it’s filtering) and how often it is used (total amount of water filtered over time).