Mercury in Water

A toxic metal with no place in drinking water.

Mercury is one of the strictest-regulated substances in drinking water, with an EPA limit of just 0.002 mg/L — among the lowest of any contaminant. It’s rare in household water, but because it targets the kidneys and nervous system, any detection is worth taking seriously and confirming properly.

What it is

Mercury is a heavy metal toxic to the kidneys and nervous system, with developing children and pregnancies at greatest risk. Unlike taste-and-odor markers, it gives no sensory warning at all — contaminated water looks, smells, and tastes normal.

How it gets into water

Industrial discharge, landfill and agricultural runoff, and erosion of natural deposits are the main routes. Proximity to industrial sites, mining history, or landfills raises the baseline risk for wells.

What a result can tell you

A clean result is meaningful reassurance for a marker you can’t sense. Any detection — given the 0.002 mg/L limit — means stop drinking the water, switch to bottled or filtered water, and get a certified laboratory analysis promptly. If confirmed, your local health department can help identify the source, and treatment options like reverse osmosis are effective.

What it can’t tell you

At these trace thresholds, a strip is a screening net, not a precision instrument — lab confirmation is essential in both directions. Note that most human mercury exposure actually comes from diet (certain fish) rather than water; if exposure is a concern, a healthcare provider can assess it properly.