Well Water Tests
What is Tested and Why?

Arsenic
Limit 0.010 mg/L

Health Concerns:
Skin damage or problems with circulatory systems and may have increased risk of getting cancer. Test more often if detected or in areas with known Arsenic issues

Potential Sources:
Erosion of natural deposits; runoff from orchards; runoff from glass & electronics production wastes

Cadmium
Limit 0.005 mg/L

Health Concerns:
Kidney damage

Potential Sources:
Corrosion of galvanized pipes; erosion of natural deposits; discharge
from metal refineries; runoff from waste batteries and paints

Chloride
Limit 250 mg/L

Health Concerns:
Can affect water taste and odor

Coliform Bacteria
Limit: Absence (0 detectable)

Health Concerns:
Coliforms are bacteria that indicate that other, potentially harmful bacteria may be present. See E.coli Bacteria

Conductivity
Limit 1000 µS/cm

The U.S. Environmental Protection Agency (EPA) recommends that drinking water conductivity should be less than 1000 µS/cm to ensure it is safe and not overly contaminated. Conductivity values outside this range may indicate potential water quality issues that require further investigation.

Copper
Limit: 1.3 mg/L

Health Concerns:
Short-term exposure: Gastrointestinal distress. Long- term exposure: Liver or kidney damage. People with Wilson’s Disease should consult their personal doctor if the amount of copper in their water exceeds the action level

Potential Sources:
Corrosion of household plumbing systems; erosion of natural deposits

E.coli Bacteria
Limit: Absence (0 detectable)

Health Concerns:
E.coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Microbes in these wastes may cause short term effects, such as diarrhea, cramps, nausea, headaches, or other symptoms. They may pose a special health risk for infants, young children, and people with severely compromised immune systems.

Possible Sources:
Human and animal fecal waste

Fluoride
Limit: 4 mg/L

Health Concerns:
Bone disease (pain and tenderness of the bones); children may get mottled teeth

Possible Sources:
Water additive which promotes strong teeth; erosion of natural deposits; discharge from fertilizer and aluminum factories

Hardness
Considered to be Soft Water if below 50 mg/L, Hard Water if above 200 mg/L

Health Concerns:
Can affect water taste and odor

Additional Information:
The EPA has not set a legal limit for water hardness, but it provides guidelines for secondary drinking water standards to help manage aesthetic issues like taste and scaling. Many water utilities aim to keep hardness levels low to avoid unpleasant effects, and homeowners often use water softeners to reduce hardness.
Optimum Range: 50 mg/L to 200 mg/L

Heterotrophic plate count (HPC)
Limit: 500 bacterial colonies per milliliter (CFU/mL)

Health Concerns:
HPC has no health effects; it is an analytic method used to measure the variety of bacteria that are common in water. The lower the concentration of bacteria in drinking water, the better maintained the water system is

Possible Sources:
HPC measures a range of bacteria that are naturally present in the environment

Iron
Limit: 0.3 mg/L

Health Concerns:
Can affect water taste and odor

Langelier Saturation Index
(LSI Index )
Typically ranges from -3.0 to +3.0, with 0.0 representing perfect chemical equilibrium.

The LSI Index is a formula used to determine if water is "balanced," corrosive, or scale-forming. It measures the saturation level of calcium carbonate in the water.

Key LSI Values and Their Meaning
Balanced (-0.30 to +0.30): This is the widely accepted "safe" range where water is considered stable.
Negative LSI (Below -0.30): The water is undersaturated and "aggressive." It will actively seek to dissolve calcium from its surroundings, which can lead to the corrosion of pipes, etching of pool plaster, and damage to equipment.
Positive LSI (Above +0.30): The water is supersaturated. Excess calcium carbonate will precipitate out of the water, forming hard mineral deposits known as scale on surfaces, filters, and plumbing.

Lead
Limit: 0.015 mg/L

Health Concerns:
Adults: Kidney problems; high blood pressure
Infants and children: Delays in physical or mental development; children could show slight deficits in attention span and learning abilities. The American Academy of Pediatrics (AAP) suggests a more stringent limit of 0.001 mg/L for children.

Possible Sources:
Corrosion of household plumbing systems; erosion of natural deposits

Magnesium
Limits: No MCL values, typical concentrations range from 1 to 100 mg/L

Health Concerns:
EPA provides no MCL, as it is generally considered non-toxic and even beneficial in moderate amounts, often contributing to water hardness, though high levels can affect taste or cause scaling in pipes.

Potential Sources:
Magnesium in well water originates from natural rock and soil dissolution or human sources like fertilizers, road salts, and industrial waste, varying by local geology, water hardness, and pH.

Manganese
Limit: 0.3 mg/L

Health Concerns:
High manganese can cause neurological health risks (especially in infants) above 0.3 mg/L, and aesthetic issues (bitter taste, black staining) above 0.05 mg/L.

Possible Sources:
Common sources include natural rock/soil leaching and human activities like agricultural runoff or industrial waste.

Naturally Occurring Radioactivity in Your Well Water.
If gross alpha is < 5 pCi/L, Massachusetts guidance indicates no additional Uranium or radium-226/228 testing is needed at that time.
If it is ≥ 5 pCi/L, add radium-226 and radium-228.
If it is ≥ 15 pCi/L, add direct uranium testing, ideally reported as mass concentration (μg/L). The applicable uranium drinking-water limit is 30 μg/L.

Natural radioactive materials in rock and soil can enter well water. They slowly change into other materials over time, creating a natural sequence:

Uranium → radium → radon gas → eventually stable lead.
Uranium: A naturally occurring metal found in some rock formations. Small amounts can dissolve into groundwater. Primarily a chemical heavy-metal concern: over many years, elevated levels may damage the kidneys.
Radium: A radioactive material formed as uranium naturally changes over time. It can also dissolve into well water. It can build up in bone; long-term radioactive exposure can raise the risk of bone cancer and other bone-related effects.
Radon: A colorless, odorless radioactive gas formed from radium. It can dissolve in well water and escape into indoor air when water is used for showering, washing, or cooking. Radon can leave water and enter household air, especially during showering and other water use. Breathing it over time raises lung-cancer risk; smoking greatly increases that risk.
Gross alpha
This is not a specific contaminant or diagnosis—it is a general screening measurement of alpha radiation from radioactive materials that may be present in water. A high result means alpha-emitting radioactive materials may be present and follow-up testing is needed to identify them.

Why testing matters
You cannot see, smell, or taste uranium, radium, radon, or alpha radiation. Testing identifies whether these naturally occurring materials are present and whether follow-up testing or water treatment should be considered.

Nitrate
Limit: 10 mg/L

Health Concerns:
Infants below the age of six months who drink water containing nitrate in excess of their MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome

Possible Sources:
Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits

Nitrite
Limit: 1000 µg/L

Health Concerns:
Infants below the age of six months who drink water containing nitrite or nitrite in excess of their MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome

Possible Sources:
Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits

Sodium
No Limit unless on low sodium intake diets

Health Concerns:
For those on low-sodium intake diets (<500mg/day) the limit is 20mg/L and can affect health (e.g., hypertension, kidney issues).
For those on a normal diet the suggested acceptable range is 30-60 mg/L, above that It may cause salty taste, plumbing corrosion, and plant damage.
Domestic water softeners can increase sodium levels to more than 300 mg/L in drinking water (NAS 1977).

Possible Sources:
Natural mineral leaching from rocks and soils; human sources like road salt runoff, leaking septic systems, fertilizers, industrial waste, sewage, and water softener backwash.

Total Dissoloved Solids (TDS)
Limit: 500ppm

The EPA Secondary Regulations advise a maximum contamination level (MCL) of 500 parts per million (ppm) for TDS. Numerous water supplies exceed this level. When TDS levels exceed 1000mg/L it is generally considered unfit for human consumption.

A high level of TDS is an indicator of potential concerns, and warrants further investigation. Most often, high levels of TDS are caused by the presence of potassium, chlorides and sodium. These ions have little or no short-term effects, but toxic ions (Arsenic, Chromium, Manganese, Nitrates and others) may also be dissolved in the water. Levels exceeding 500 mg/L often cause hard water, scale buildup in pipes and appliances, and a salty or metallic taste.

pH
Limit: 6.5 to 8.5

Health Concerns:
Can affect water taste and odor