Why zero TDS matters for coffee

Most brew water recipes start from demineralised or very low ppm water, because you can only control the mineral content of your water if you begin from close to nothing. Ordinary carbon filter jugs improve taste and reduce chlorine, but they leave most dissolved minerals in place, so you never know your true starting point.

ZeroWater uses ion exchange resin, which removes dissolved solids rather than just adsorbing organics. The output measures at or near 000 ppm, which makes it a practical base for mineral concentrates such as the APAX LAB range, or for any water recipe you want to mix yourself.

How the five stages work

Water passes through a coarse screen that catches sediment and rust, then a foam distributor that evens out flow and removes finer particles. The third stage combines activated carbon with an oxidation reduction alloy to take out chlorine and organic compounds and reduce metals. The fourth stage is the ion exchange resin that does the actual TDS removal, targeting nitrates, fluoride and heavy metals. A fine screen and non-woven membrane finish the job.

Doing more work means it flows more slowly than a two-stage carbon jug. This is normal and not a fault.

Certification

The 5-stage filter and compatible jugs are certified by IAPMO R&T against NSF/ANSI Standard 42 for chlorine taste and odour reduction, and against NSF/ANSI Standard 53 for reduction of lead, hexavalent chromium, PFOA, PFOS and mercury, at a 15-gallon rated capacity.

Using the TDS meter

Measure your tap water first, then the filtered output. A fresh filter should read 000 to 002 ppm. Replace the filter once the reading reaches 006 ppm or higher. Two taste changes signal the same thing: a sour or lemon-like note means the resin is releasing hydrogen ions as it reaches capacity, and a fishy or ammonia note means it is spent. Neither is a defect, both are the cartridge telling you it is done.

Filter life in Norwegian conditions

Filter life depends almost entirely on the TDS of your incoming tap water, not on time. ZeroWater’s own guidance puts tap water in the 002 to 050 ppm range at 40 or more gallons per filter, roughly 150 litres, while water in the 301 to 400 ppm range yields only around 8 to 15 gallons. Norwegian tap water is generally soft and low in dissolved solids compared with much of continental Europe, so most households here should sit in the favourable end of that scale. Measure your own tap water with the included meter and you will know what to expect.

Specifications

What’s in the box

• ZeroWater 1.7L jug
• 1 × 5-stage filter
• Digital TDS meter
• Instruction manual

Good to know

Do not use with water that is microbiologically unsafe or of unknown quality without adequate treatment first. The filter removes beneficial minerals along with everything else, so if you are drinking this water rather than brewing with it, you may want to remineralise.