Private well water

On a well? Nobody tests it but you.

Public water rules don't cover private wells, so there's no annual report to look up. These are the contaminants Maryland well owners most often test for. The only way to know what's in your well is to test it.

Book a free well water test Call 410-924-6138

Who's responsible? According to EPA, private well owners are responsible for the safety of their own water. EPA: Private wells

How often to test: CDC recommends testing well water at least once a year for total coliform bacteria, nitrates, total dissolved solids, and pH, and more often if anything changes. CDC: Testing well water

Coliform bacteria & E. coli

What it is

Coliforms are bacteria that are common in the environment. Water systems test for them as an indicator: their presence means germs may be able to get into the water. E. coli is a specific type that indicates fecal contamination.

Your body

According to EPA, germs indicated by E. coli can cause stomach cramps, diarrhea, nausea, and headaches, and may pose a special risk for infants, young children, and people with severely compromised immune systems.

Your home

Bacteria do not damage plumbing, but in wells they can point to a cracked well cap, a damaged casing, or nearby septic issues.

Federal standard: Treatment technique; E. coli MCL (EPA Revised Total Coliform Rule)

Treatment options that can reduce it

UV disinfection works best with sediment pre-filtration in front of it, and the well should also be inspected.

Research & sources (3)

Full guide to coliform bacteria & e. coli →

Nitrate

What it is

A form of nitrogen from fertilizer, manure, and septic systems that can soak into groundwater. It is a common concern in farming areas, including much of the Eastern Shore.

Your body

According to EPA, infants under six months who drink water with nitrate above the federal limit could become seriously ill (blue baby syndrome). Research has also examined links between long-term exposure and other health effects.

Your home

Nitrate does not harm plumbing. It can indicate that surface water or septic waste is reaching a well.

Federal standard: MCL 10 ppm as nitrogen (EPA)

Treatment options that can reduce it

Reverse Osmosis

Look for an RO system certified to NSF/ANSI 58 for nitrate reduction.

Research & sources (3)

Full guide to nitrate →

Arsenic

What it is

A naturally occurring element found in some rock and soil, and in past use in pesticides and wood preservatives. It has no taste, color, or smell. Some Maryland aquifers contain natural arsenic.

Your body

Long-term exposure has been linked to skin changes, circulatory problems, and an increased risk of bladder, lung, and skin cancers (EPA, WHO). EPA’s health goal is zero.

Your home

Arsenic at levels found in drinking water does not usually harm plumbing or appliances.

Federal standard: MCL 10 ppb; health goal 0 (EPA)

Treatment options that can reduce it

Reverse Osmosis

Arsenic comes in two forms. Some wells need a pre-treatment step before reverse osmosis works well, which a water test will show.

Research & sources (4)

Full guide to arsenic →

Radon

What it is

A radioactive gas from the natural breakdown of uranium in rock. It can dissolve into well water and is released into the air when water is used for showers, laundry, and dishes.

Your body

Most of the health risk comes from breathing radon released into indoor air. Radon is a leading cause of lung cancer after smoking (EPA, WHO), and drinking radon in water has been linked to a smaller risk of stomach cancer (National Academies).

Your home

Radon does not affect plumbing.

Federal standard: No federal MCL for drinking water

Treatment options that can reduce it

Whole-Home Filtration

Radon in well water is usually treated at the point of entry, typically by aeration or, at lower levels, activated carbon. Test your indoor air as well.

Research & sources (4)

Full guide to radon →

Iron

What it is

A common natural mineral in Maryland groundwater, especially on the Eastern Shore. It can also come from rusting pipes.

Your body

EPA treats iron as a cosmetic (secondary) issue rather than a health risk at levels found in drinking water.

Your home

Iron causes orange-brown stains on sinks, tubs, toilets, and laundry, and a metallic taste. It can also feed iron bacteria and clog pipes, valves, and water treatment equipment.

Federal standard: Secondary standard 0.3 ppm (EPA, non-enforceable)

Treatment options that can reduce it

The right iron treatment depends on the amount and type of iron. A water test tells us which.

Research & sources (2)

Full guide to iron →

Manganese

What it is

A naturally occurring mineral often found with iron in groundwater.

Your body

Manganese is a nutrient in small amounts. At higher levels in drinking water, it has been linked in some studies to effects on children’s learning and behavior. EPA has a health advisory level in addition to its cosmetic standard.

Your home

Manganese causes black or brown stains on fixtures and laundry, a bitter taste, and black sediment in pipes and water heaters.

Federal standard: Secondary standard 0.05 ppm (EPA, non-enforceable)

Treatment options that can reduce it

Research & sources (3)

Full guide to manganese →

Hardness (calcium & magnesium)

What it is

Hardness is the amount of dissolved calcium and magnesium in water, picked up as water moves through limestone and other rock.

Your body

Hard water is not considered a health risk. Calcium and magnesium are common dietary minerals.

Your home

Hard water leaves scale inside water heaters, dishwashers, coffee makers, and pipes, which can reduce efficiency and shorten equipment life. It also leaves spots on glass, crust on faucets and showerheads, and makes soap lather poorly.

Federal standard: No federal limit

Treatment options that can reduce it

Water Softeners

Research & sources (2)

Full guide to hardness →

pH (acidic or corrosive water)

What it is

pH measures how acidic or basic water is. Many Maryland wells, especially in Coastal Plain aquifers, have naturally low pH (acidic) water.

Your body

pH itself is not a direct health concern, but acidic water can dissolve lead and copper from plumbing into the water you drink.

Your home

Acidic water corrodes copper pipes and fixtures, causing pinhole leaks and blue-green stains, and shortens water heater life.

Federal standard: Secondary range 6.5–8.5 (EPA, non-enforceable)

Treatment options that can reduce it

Remineralization

Acid-neutralizing (remineralizing) filters raise pH for the whole home.

Research & sources (3)

Full guide to ph →

Lead

What it is

A metal that usually gets into tap water from lead service lines, lead solder, and older brass fixtures inside buildings, not from the water source itself. Homes built before 1986 are more likely to have lead plumbing.

Your body

EPA has set a health goal of zero for lead because no safe level of exposure is known. In children, low-level lead exposure has been linked to lower IQ, learning and attention problems; in adults, to raised blood pressure and kidney effects. Pregnant women and young children are most at risk.

Your home

Lead itself does not damage plumbing, but its presence is a sign of corrosion: water chemistry that dissolves metal from pipes, solder, and fixtures.

Federal standard: Action level 15 ppb; health goal 0 (EPA)

Treatment options that can reduce it

For drinking water, look for a system certified to NSF/ANSI 53 or 58 for lead reduction.

Research & sources (5)

Full guide to lead →

Copper

What it is

A metal that mostly enters tap water from corrosion of copper pipes and brass fixtures, especially when water is acidic (low pH) or sits in pipes for hours.

Your body

According to EPA, short-term exposure above the action level has been linked to stomach and intestinal upset. Long-term exposure has been linked to liver or kidney damage, and people with Wilson’s disease are more sensitive.

Your home

Copper in water points to pipe corrosion, which can lead to pinhole leaks over time. It also leaves blue-green stains on sinks, tubs, and fixtures.

Federal standard: Action level 1.3 ppm (EPA)

Treatment options that can reduce it

Reverse osmosis reduces copper at the tap. On well systems, correcting acidic water can reduce how much copper the pipes release.

Research & sources (3)

Full guide to copper →

Radium

What it is

A naturally occurring radioactive element in some rock and soil, found in certain Maryland aquifers. Reports list radium-226, radium-228, or the two combined.

Your body

According to EPA, long-term exposure above the federal limit has been linked to an increased risk of cancer.

Your home

Radium does not affect plumbing, but it can build up in softener resin and filter media.

Federal standard: MCL 5 pCi/L combined radium-226/228 (EPA)

Treatment options that can reduce it

Research & sources (3)

Full guide to radium →

PFAS (“forever chemicals”)

What it is

Per- and polyfluoroalkyl substances are a large family of man-made chemicals used since the 1940s in non-stick, stain- and water-resistant products and firefighting foams. They break down very slowly in the environment and the body.

Your body

Exposure to certain PFAS, such as PFOA and PFOS, has been linked to effects including changes in cholesterol, reduced vaccine response in children, lower birth weight, and increased risk of some cancers (EPA; Fenton et al., 2021). In 2024, EPA set drinking water limits for several PFAS.

Your home

PFAS do not affect plumbing or appliances.

Federal standard: EPA 2024 rule: PFOA and PFOS 4.0 ppt; see EPA for others

Treatment options that can reduce it

Look for systems certified to NSF/ANSI 53 or 58 for PFOA/PFOS reduction.

Research & sources (4)

Full guide to pfas →

The information on this site is for general education only and is not medical advice. Talk with a qualified health professional about health concerns. Water treatment equipment performance depends on the system, its certification, and proper maintenance.

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