As mentioned earlier in this article, there are quite a variety of contaminants worth removing from your tap water. The team here at our lab settled on three primary tests to benchmark the efficacy of these filters: TDS, pH and chlorine. Before we began the actual testing process, each pitcher was removed from the packaging, cleaned and then prepared per the manufacturer's instructions. This is very important, as most of these filters utilize activated carbon filtration, which will deposit sediment into the first batches of water that you filter if not cleaned properly in advance.
Testing for TDS
TDS stands for total dissolved solids and encompasses many different impurities present in water. Examples of the most common TDS include "calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride, nitrate and silica," according to the US Geological Survey. In practice, calcium and magnesium deposits in tap water result in so-called "hard water" that tastes bad and can be actively detrimental to your health at higher concentrations. (Read more about TDS from the EPA and USGS.)
We began TDS testing by mixing an 8-gallon bucket of tap water, measured at a concentration of 220 ppm TDS, with table salt until we reached a TDS measurement of 300. Generally speaking, 50-150 TDS is considered an ideal range for drinking water. We used an Orapxi water quality tester to take these measurements and since the ZeroWater filter includes a TDS tester as well, all TDS readings were verified on both devices. Once we had established our control source, we measured 1 liter of the 300 TDS water into each of the water filter pitchers and allowed the full quantity to pass through the filter.
Once finished, we measured the TDS again and noted the percentage change using the pre- and post-filtration TDS measurements. This process was repeated for higher and lower TDS concentrations, and our findings indicate that each of the units we tested is very consistent at removing the same percentage of overall TDS from any water passing through it.
TDS test results
TDS (% change)
Aarke Purifier -39
Brita Metro Standard -45.6
Brita Everyday -45.6
... continue reading