What’s Really in Well Water? Common Contaminants (And Why Testing Matters)

If your home runs on well water, you already know one thing: it’s different from city water. What’s less obvious is how different it can be from one property to the next — even homes just a few miles apart.

Unlike municipal water, well water isn’t treated or standardized. What comes out of your taps depends heavily on local geology, soil composition, nearby land use, and even seasonal changes.

Here’s a breakdown of what’s commonly found in private well water — and why guessing instead of testing can lead to the wrong filtration setup.

Minerals: The Most Common Issue (Hard Water)

Hard water is one of the most widespread well water problems. It’s caused by dissolved minerals like calcium and magnesium picked up as groundwater moves through rock and soil.

Common signs:

• White scale on faucets and showerheads
• Spotty dishes and cloudy glassware
• Dry skin and brittle hair
• Reduced lifespan of water-using appliances

Hard water isn’t usually a health concern, but it is rough on plumbing and daily use — and it often requires treatment at the whole-house level, not just a single tap.

Iron & Manganese: Staining and Metallic Taste

Iron and manganese are especially common in deeper wells.

You might notice:

• Reddish-brown or black stains in sinks and toilets
• Metallic or bitter taste
• Discolored laundry
• Sludge buildup in pipes

These minerals aren’t always harmful at low levels, but they can cause major cosmetic and plumbing headaches if left untreated.

Sulfur (Hydrogen Sulfide): The “Rotten Egg” Smell

That unmistakable rotten egg odor usually points to hydrogen sulfide gas or sulfur-reducing bacteria.

It’s often strongest:

• In hot water
• After water sits in pipes overnight
• During certain seasons

Sulfur doesn’t just smell bad — it can corrode plumbing and make water unpleasant to use for bathing or cooking.

Sediment: Sand, Silt, and Grit

Sediment enters well water naturally as groundwater moves underground.

Common effects include:

• Gritty water
• Clogged fixtures
• Premature wear on appliances
• Reduced effectiveness of other filters

Sediment is often the first thing that should be addressed, since it can interfere with more advanced filtration stages downstream.

Agricultural & Environmental Contaminants

Depending on where you live, well water can also contain:

• Nitrates from fertilizers
• Pesticides and herbicides
• Volatile organic compounds (VOCs)
• Fuel or solvent residues

These are harder to detect without proper testing — and harder to treat without the right filtration approach.

Why One Filter Rarely Solves Everything

This is where many well owners go wrong.

A single under-sink or faucet filter might improve taste, but it won’t:

• Protect your plumbing
• Stop scale buildup
• Treat water for showers, laundry, or appliances
• Address multiple contaminants at once

Well water issues usually exist throughout the home, not just at the kitchen sink.

That’s why many homeowners eventually move toward systems that treat water at the point it enters the house — especially when multiple issues (hardness, iron, sulfur, sediment) are present.

For homeowners dealing with ongoing well water issues, whole house filtration is often used to treat water at the point of entry. This breakdown of well water filtration systems outlines how different contaminants are addressed at a whole-home level.

Testing First, Treating Second

Before choosing any filtration setup, water testing is the smartest first step. It tells you:

• What contaminants are actually present
• How severe they are
• What type of treatment makes sense

From there, filtration decisions become much clearer — and far less expensive in the long run.