Iron, manganese, and hard water in wells

Most everyday complaints about well water come down to minerals from the rock and soil around the well. They stain fixtures, clog pipes, and taste odd, but mostly they aren't health hazards. EPA covers them with secondary standards, which are guidelines for taste, odor, color, and staining rather than enforceable health limits.

Iron

Iron is common in groundwater. EPA's secondary standard is 0.3 mg/L. Above that you may see orange or reddish-brown stains in sinks, toilets, and laundry, taste something metallic, or find water that comes out clear but turns rusty after standing. Iron can also feed iron bacteria, which leave slimy orange deposits in toilet tanks and can cause odors.

Iron at these levels isn't considered a health risk, but it's a nuisance and can shorten the life of water heaters and fixtures.

Manganese

Manganese often travels with iron. EPA's secondary standard is 0.05 mg/L. Above that you may see black or brownish-black stains and notice a bitter, metallic taste. Unlike iron, manganese also has a health angle. EPA has a lifetime health advisory for adults of 0.3 mg/L, with lower guidance for infants. If your well is over 0.3 mg/L, treat manganese as a health issue, not just a staining problem. Our test reader flags both levels.

Hardness

Hard water carries dissolved calcium and magnesium. It's not a health concern, but it leaves scale on fixtures and in water heaters, makes soap lather poorly, and leaves spots on dishes. There's no federal standard. The USGS uses these classes, measured as mg/L of calcium carbonate:

• 0 to 60 mg/L: soft
• 61 to 120 mg/L: moderately hard
• 121 to 180 mg/L: hard
• more than 180 mg/L: very hard

Some labs and softener sellers use grains per gallon. Multiply grains per gallon by 17.1 to get mg/L.

Other secondary standards

EPA also sets secondary levels for pH (6.5 to 8.5), total dissolved solids (500 mg/L), chloride (250 mg/L), and sulfate (250 mg/L), among others. Low pH deserves attention. Acidic water can dissolve lead and copper from plumbing, which turns a nuisance into a health issue. If your pH is low, test for lead and copper too.

Treatment basics

The right treatment depends on the combination of minerals, pH, and whether bacteria are present, so start with a full lab test. Common options:

• Water softeners (ion exchange) remove hardness and can handle low levels of dissolved iron.
• Oxidizing filters (for example, greensand or air-injection systems) turn dissolved iron and manganese into particles and filter them out.
• Neutralizing filters raise the pH of acidic water.
• Shock chlorination can knock back iron bacteria. See shock chlorinating a well.

On a septic system, ask whether a softener's backwash brine is suitable for your system. Some installers and health departments recommend routing it elsewhere. After installing any treatment, test the treated water to confirm it's working.

How to tell which mineral you have

The stain color is often the first clue:

What you see	Likely cause
Orange, red or rust-brown stains	Iron
Black or dark brown stains, or black specks	Manganese
White crust on faucets and showerheads, spotty glasses	Hardness (calcium and magnesium)
Slimy orange or brown film in the toilet tank	Iron bacteria
Rotten-egg smell	Hydrogen sulfide or sulfate-reducing bacteria

EPA's well testing chart points the same way. It links stained plumbing fixtures and laundry to iron, copper and manganese, scaly residues and soap that won't lather to hardness, and objectionable taste or smell to hydrogen sulfide, corrosion or metals. EPA also notes that if you need a water softener for hardness, you should test for manganese and iron too.

Clear-water iron vs. red-water iron

Iron shows up in two main forms:

• Ferrous ("clear-water") iron is dissolved. Water comes out of the tap clear, then turns cloudy or rusty after standing or heating, as the iron reacts with oxygen.
• Ferric ("red-water") iron is already oxidized. Water comes out of the tap with visible rust-colored particles.

The form matters for treatment. Softeners can handle small amounts of dissolved iron, while oxidizing filters handle higher levels or both forms. Iron bacteria call for disinfection and sometimes continuous treatment.

Hardness: when to treat

USGS describes hard water as high in dissolved calcium and magnesium. When it's heated, it forms calcium carbonate scale that can shorten the life of equipment, raise water-heating costs and clog pipes. USGS also notes hard water isn't a health concern, and the World Health Organization says drinking water may contribute calcium and magnesium to the diet. Many households soften water once it reaches the "hard" range (above 120 mg/L) to protect water heaters and fixtures. Others simply soften the hot water line. If anyone in the home is on a sodium-restricted diet, ask about potassium-based softening, or leave one cold tap unsoftened for drinking.

Testing tips

• Use a state-certified lab. CDC recommends certified labs for all well testing.
• Ask for iron, manganese, hardness, pH and total dissolved solids together. Treatment depends on the whole picture.
• Test before and after treatment to confirm the system is working and sized correctly.
• Include the annual basics. CDC and EPA recommend testing yearly for coliform bacteria, nitrate, total dissolved solids and pH.

Living with minerals until you treat

• Clean stains promptly with a product made for rust or mineral deposits.
• Flush the water heater periodically to remove sediment.
• Use detergents formulated for hard water.
• Use bottled water for drinking if manganese is above EPA's health advisory level while you arrange treatment.

Key takeaways

• Stain color helps identify the mineral, but a lab test confirms it.
• Iron and hardness are mostly nuisances. Manganese can be a health concern at higher levels.
• Treatment depends on the combination of minerals, pH and bacteria.
• Retest after installing any treatment system.