The number on your TDS meter is the signal that matters most for a ZeroWater filter. Here is what a reading of 006 means, why ZeroWater recommends changing the filter at that point, and what ZeroWater filters are certified to reduce.
What the 006 reading tells you
Your ZeroWater TDS meter shows the level of dissolved solids in your filtered water in parts per million (ppm). A new filter typically reads 000. ZeroWater recommends replacing the filter when the meter reads 006 or higher, and recommends not letting the reading go past that point.
What TDS means
Total dissolved solids (TDS) are organic and inorganic materials, such as metals, minerals, salts, and ions dissolved in water. TDS can affect the taste and appearance of water. A TDS meter measures dissolved solids only. It cannot detect other contaminants such as lead or PFOA/PFOS. For a longer explanation, read what is TDS.
Why a filter works less well over time
ZeroWater's 5-stage filter uses ion-exchange resin as one of its stages, and like any filter, it has a limited capacity. The more dissolved solids in your tap water, the sooner that capacity is used up. When it is, the reading on your meter rises. That is why the meter, not a calendar, is the best way to know when to change the filter. See how long filters typically last by tap water TDS.
What ZeroWater filters are certified to reduce
ZeroWater pitcher systems are certified by IAPMO R&T against NSF/ANSI Standard 53 to reduce the following substances. In testing, they reduced:
| Substance | Reduction in testing |
|---|---|
| Lead | 98.9% at pH 6.5, 98.8% at pH 8.5 |
| PFOA/PFOS | 99.8% |
| Hexavalent chromium | 99.4% at pH 6.5, 99.5% at pH 8.5 |
| Mercury | 96.6% at pH 6.5, 94.2% at pH 8.5 |
The systems are also certified against NSF/ANSI Standard 42 for chlorine, an aesthetic effect (99.4% in testing). Certification covers the contaminants listed above. TDS reduction is a performance feature and is not part of the certification.
Actual performance may vary, and not all contaminants reduced are necessarily in your water. Read the full results on our performance certification page.
Want to learn more about PFOA/PFOS? Read what forever chemicals are doing in your tap water.
Make it automatic: auto-delivery
Because filter life depends on your water and your household, many owners set up auto-delivery so a new filter arrives before the old one is used up. See auto-delivery options or shop replacement filters.
Frequently asked questions
What does a TDS reading of 006 mean?
It means the dissolved solids in your filtered water have reached the level at which ZeroWater recommends replacing the filter.
Can I keep using the filter after the meter reads 006?
ZeroWater recommends not letting the reading go past 006 and changing the filter at that point.
Does the TDS meter detect lead or PFOA/PFOS?
No. A TDS meter measures dissolved solids only. It cannot detect other contaminants.
What are ZeroWater filters certified to reduce?
Lead, PFOA/PFOS, hexavalent chromium, and mercury (NSF/ANSI Standard 53), and chlorine (NSF/ANSI Standard 42), as certified by IAPMO R&T. See the table above and the performance certification page.
