Photograph by Linus Bohman via Creative Commons
A new ready-pour water pitcher from ZeroWater showed up for a test-run, and it intrigued me because it came with its own TDS meter. Full disclosure of stupidity: I didn’t even know what TDS was.
Total Dissolved Solids.
I dipped the meter and gulped in shock. My tapwater in Waterloo, Illinois, which had always tasted so good, was 647—one of the highest in the area. I raced to work and tested the Brentwood tap water. It was 256.
Hurriedly, I filled the pitcher (designed with a giant reservoir to eliminate any drip-by-drip tedium) and whipped out the meter again. Zero.
Then I did some research. It urns out that a high TDS level is not an automatic health hazard at all. Those solids might be minerals. And according to the World Health Organization, certain concentrations of TDS may even be good for you.
TDS is as much an aesthetic issue as anything, because some solids can give water a brackish or rusty taste. The U.S. Food and Drug Administration has aesthetic criteria of 500 mg/l for drinking water and doesn’t worry about odor, taste, or color at levels below that.
Still, TDS can include pesticides, runoff, de-icing salts, pollution discharge… and might even include elevated levels of arsenic, copper, aluminum, lead, nitrate, etc.
How much you should worry depends on what solids are dissolved in your water. Last year, researchers from the Environmental Protection Agency and the U.S. Geological Survey tested water in 25 municipalities. In one-third of the water supplies, they found traces of unregulated contaminants, 18 all told, including 11 perfluorinated compounds, an herbicide, two solvents, caffeine, an antibacterial compound, a metal, and an antidepressant.
If you do need a little purification (of your drinking water; we’re not commenting on your soul), the ZeroWater pitcher and tumbler use a five-stage filter. The company says it “provides the only filtered water that meets the FDA definition of purified bottled water.”
I poured a glass and took a sip. Then a sip of tap water. My husband did the same, solemn as a wine taster.
ZeroWater was fine, we agreed, but didn’t taste any better.
We slid back to drinking our liquid solids about half the time, whenever the ZeroWater pitcher was empty. But just as I was relaxing, a study at the University of Oregon popped into my inbox, warning that arsenic levels are worrisome in groundwater all over the country, and organic arsenic can be a cancer risk…and can convert into “arsine, a volatile gas similar to fluorescent phosphine that arises as the result of decomposition in graveyards.”
I filled the pitcher again.
