Well water contaminants
What can be in the water, and where it comes from
Grouped by the direction it reaches a well from. The last line on each card says whether you'd ever notice it on your own — for most of the ones that matter for health, you wouldn't.
From the rock
Dissolved out of the rock and sediment the water sits in. Set by geology, so neighbours on the same aquifer often share them.
ArsenicFrom the rockCan't see, smell or taste itRadonFrom the rockCan't see, smell or taste itIron & ManganeseFrom the rockOrange or black stains, metallic tasteUraniumFrom the rockCan't see, smell or taste itHardnessFrom the rockScale on fixtures, soap that won't latherChromium-6 (Hexavalent Chromium)From the rockCan't see, smell or taste itFluorideFrom the rockCan't see, smell or taste itRadiumFrom the rockCan't see, smell or taste itHydrogen SulfideFrom the rockRotten-egg smellSulfateFrom the rockBitter taste at high levels
From the land above
Carried down from the surface — septic systems, fields, fuel tanks, industrial sites. Shallow wells and limestone are most exposed.
NitratesFrom the land aboveCan't see, smell or taste itPFAS (Forever Chemicals)From the land aboveCan't see, smell or taste itBacteria (Coliform & E. coli)From the land aboveCan't see, smell or taste itVOCs (Petroleum & Solvents)From the land aboveA fuel or solvent smell, only at high levelsPesticidesFrom the land aboveCan't see, smell or taste it
From your plumbing
Picked up between the well and the tap. Your aquifer can't tell you about these; the age of your plumbing can.
From the sea
Near the coast, heavy pumping can pull seawater into a freshwater aquifer.