Cyanide
CN⁻·Affects brain, heart
A fast-acting industrial toxin from metal plating, mining, and chemical manufacturing waste. Blocks cellular oxygen use at acute doses. EPA MCL is 0.2 mg/L as free cyanide.
CN⁻
EPA limit
0.2 mg/L (MCL)
Most at risk
Residents near gold mining, electroplating, or chemical-manufacturing facilities; well users near industrial spill sites
Found in
City water · Well water · Industrial areas
AquaOx filters
YesActivated carbon
What it does to you
Health effects
Cyanide is one of the fastest-acting toxins known. It binds to cytochrome c oxidase in mitochondria, shutting down cellular respiration: cells can no longer use oxygen even when oxygen is present. Acute high-dose exposure causes rapid loss of consciousness and death from cellular asphyxiation within minutes.
Chronic low-dose exposure through drinking water is associated with neurological effects, including peripheral neuropathy, vision changes, and goitrogenic effects on the thyroid. The nervous system and the heart are the primary chronic target organs.
The EPA set the 0.2 mg/L MCL to protect against both acute and chronic effects, with a safety margin built in for sensitive populations. People with iodine deficiency or pre-existing thyroid disease are more vulnerable to the goitrogenic effects of chronic low-dose cyanide.
Where it comes from
How it gets into your water
Cyanide enters drinking water primarily from industrial discharge. The largest sources are gold and silver mining (cyanide leaching is the dominant extraction process worldwide), electroplating operations (cyanide baths for copper, silver, and gold plating), steel hardening, chemical manufacturing, and the production of plastics and synthetic fibers like nylon and acrylic.
Spills from cyanide-tailings ponds at gold mines have caused some of the most severe waterborne cyanide events in recent decades, including the 2000 Baia Mare disaster in Romania.
Smaller continuous sources include road salt (some formulations contain cyanide-based anti-caking agents), runoff from disposal sites, and incomplete combustion products that wash into surface water with rainfall.
Gold and silver mining
Cyanide leaching extraction process
Electroplating operations
Cyanide-based copper, silver, gold plating baths
Chemical and plastics manufacturing
Nylon, acrylic, and synthetic-fiber production
Steel hardening (case hardening)
Industrial heat-treatment processes
Find out for yourself
Is it in your water?
Cyanide is included in the standard inorganic package every utility tests and reports on their Consumer Confidence Report. Detection at or above the MCL in finished tap water is uncommon under normal conditions.
Private well owners within a few miles of active or legacy gold or silver mining operations, electroplating shops, or chemical manufacturing facilities should test for cyanide specifically. Communities downstream of any reported tailings-pond leak or industrial spill should also test.
Because cyanide is volatile and unstable, samples need to be collected, preserved, and shipped per the lab's protocol to get an accurate reading.
The fix
How AquaOx filters it
Activated carbon, the centerpiece of every AquaOx system, adsorbs cyanide effectively. The Centaur catalytic carbon and coconut shell carbon stages capture cyanide as water passes through, with the catalytic carbon offering additional reactivity for the most stable cyanide complexes.
Because cyanide is so acutely toxic, AquaOx recommends pairing the whole-house system with a point-of-use reverse osmosis unit at the kitchen sink whenever cyanide is a documented concern in your area. The combination of carbon adsorption and RO rejection gives you redundant protection for drinking and cooking water.