The Metals Analysis: Iron (II), Iron (III), Manganese, Zinc, Nickel, Lead, and
Many metals are essential nutrients at low concentrations, but cause metallic tastes, stain-
ing, cloudiness, and have potential toxic effects at higher concentrations
There are three forms, or “oxidation states,” of iron that we encounter in daily life. Metallic
iron is the kind found in steel. Ferrous iron is one step more oxidized, and can dissolve in
water. It is colorless and can reach high concentrations, if no oxygen is present. When oxy-
gen (or another oxidizing chemical) is present, ferrous iron is converted to ferric iron, which
forms the familiar oxides that we call “rust.”
Some ground water can contain relatively large amounts of ferrous iron. When we use it
in our homes, the iron becomes oxidized and forms brown stains on plumbing fixtures and
metallic tastes. Concentrations above 0.3 ppm can cause staining. In some cases, signifi-
cant amounts of iron can come from corrosion of plumbing, but this is rare.
Manganese is common in some aquifers, especially where volcanic rocks are present. It
acts much like iron, and can cause brown or black stains when it is oxidized.
Copper, Zinc, Nickel
While these metals can be found in some aquifers (usually near mines or smelters) they
usually come from corrosion of metal pipes in your water system. We can almost always
tell what kind of pipes you have, from this analysis. These metals are essential nutrients,
but at high concentrations, they can cause adverse health effects. Note that these met-
als can be more toxic to plants than to humans, so limits are lower for irrigation water.
In older homes, lead may be present in the solder of copper pipes. It can leach into the
water, particularly if the water is acidic. Long-term exposure is considered quite hazard-
What to do?
If your ground water has excessive iron and manganese, it can be removed using oxidiz-
ing sand filters. These filters require periodic maintenance, or they will eventually stop
If you have excess copper, zinc, and nickel, and you don‘t live near a mine or a smelter, it
is probably coming from your pipes. If your water is very acidic, (see “pH”) it may be
causing excessive corrosion. You may need a neutralization device to correct for acidic
water. Or you may consider replacing old pipes, or switching to plastic pipes, where pos-