Arsenic
As·Affects skin,, heart, bones, lungs
A naturally occurring heavy metal classified by the EPA and IARC as a known human carcinogen. Contaminates groundwater across large parts of the United States, especially in the West and the Midwest.
As
EPA limit
0.010 mg/L (10 ppb)
Most at risk
Private well users, residents of the Southwest and upper Midwest, long-term consumers
Found in
City water · Well water · Industrial areas
AquaOx filters
YesKDF-55 + activated carbon (paired with RO for arsenic-heavy sources)
What it does to you
Health effects
Arsenic is classified by the EPA and the International Agency for Research on Cancer (IARC Group 1) as a known human carcinogen. Long-term exposure through drinking water is linked to cancers of the skin, lung, and bladder, plus kidney and liver tumors at higher exposure levels.
Beyond cancer, chronic low-dose arsenic exposure damages the cardiovascular system: large epidemiological studies tie it to elevated rates of heart disease, hypertension, and stroke. Skin effects include hyperpigmentation, thickening on the palms and soles (hyperkeratosis), and characteristic lesions. Arsenic also weakens bone density over decades of exposure.
Acute high-dose exposure causes nausea, abdominal pain, and peripheral neuropathy, but the bigger public health concern in the United States is the chronic, low-level exposure that millions of well users absorb daily without symptoms.
Where it comes from
How it gets into your water
Most arsenic in US drinking water is natural, leached from arsenic-bearing rock and soil into groundwater. Geological hot spots include the Southwest (Arizona, New Mexico, Nevada), parts of California, the upper Midwest (Wisconsin, Michigan, Minnesota), and the Northeast (New England states with granite bedrock).
Industrial sources add to the burden in some areas: historic mining and smelting, coal-fired power plants, semiconductor manufacturing, and the legacy of arsenical pesticides (chromated copper arsenate wood preservatives, lead arsenate orchard sprays) that have leached into shallow aquifers.
Municipal utilities are required to treat city water down to the federal 10 ppb limit. Private well owners are responsible for their own testing, and many never test.
Natural geology
Leached from arsenic-bearing bedrock into groundwater
Mining and smelting
Historic and active operations
Legacy pesticides
Arsenical orchard sprays and wood preservatives
Coal combustion
Fly ash leachate from power plants
Find out for yourself
Is it in your water?
If you're on city water, your utility's annual Consumer Confidence Report (CCR) lists the arsenic level. The federal limit is 10 ppb, but health researchers note that effects appear well below that, so a "compliant" reading is not the same as a safe one.
Private well users should test for arsenic at least once: it's geological, so if your aquifer has it, you have it. State health departments often publish arsenic risk maps, and the USGS has nationwide groundwater data showing which counties exceed 10 ppb. Wells in known hot spots (parts of Maine, New Hampshire, Nevada, Arizona, the Dakotas) should be tested every few years.
The fix
How AquaOx filters it
AquaOx's KDF-55 media reduces arsenic through redox chemistry, with the copper-zinc alloy converting soluble arsenic species into insoluble forms that get trapped in the filter bed. The activated carbon stage adds adsorptive capacity for residual arsenic.
For well sources with arsenic levels close to or above the EPA limit, AquaOx recommends pairing the whole-house system with a point-of-use reverse osmosis unit at the kitchen sink. RO filters both arsenic(III) and arsenic(V) species to below detection in independent testing, giving you a redundant barrier at the tap where you drink.