Iron is a common drinking water contaminant coming from natural mineral deposits in the ground but also from man-made sources, most commonly corroding pipes or other rusty (i.e., iron oxide) runoff. Common signs of high levels of iron in your drinking water is an orange/rusty hue, some sediment or particulate, and a metallic taste. The EPA maximum contamination level or action level for iron is 0.300 mg/L.
Copper is a drinking water contaminant primarily caused by corroding pipes that are made from Cu. Water that is acidic (i.e. low pH < 6.0) or water treated with a water softening system can dissolve copper pipes over an extended period, leading to potential plumbing issues and copper contamination. A common sign of copper contamination is a metallic taste in your water. The EPA maximum contamination level or action level for copper in drinking water is 1.3 mg/L.
Manganese contamination in drinking water is most attributed to natural deposits in the ground. Rainwater seeping into the ground dissolves manganese from rocks and soil where it is deposited near in-ground drinking water sources. Elevated levels of manganese in your water are commonly indicated by dark and murky brown water which can stain plumbing fixtures and clothes and lead to health problems in severe cases. The EPA maximum contamination level or action level for manganese in drinking water is 0.050 mg/L.
Lead is a highly toxic drinking water contaminant which is more commonly an issue in homes built before 1986. The most common source of lead contamination is the corrosion of pipes in older (pre-1986) plumbing systems, which can be further accelerated by acidic water (i.e. low pH < 6.0). Another possible source of lead contamination is water runoff and rainfall near older structures with lead features such as lead-based paint, leading to contamination in the groundwater in that area. The EPA maximum contamination level or action level for lead in drinking water is 0.015 mg/L.
Calcium and magnesium in your drinking water is not a health risk but can have other undesirable effects in high concentrations. They are both naturally found in many different forms in the ground and are the two minerals responsible for the “hardness” of your water. Particularly hard water can lead to salt-like scale buildup on your plumbing fixtures, dry skin, and reduce the effectiveness of soap. Knowing these mineral levels in your water can help to inform you on how to adjust the hardness through treatment with softeners if necessary.
To determine Hardness of water, the concentrations of calcium and magnesium are determined individually and then a Hardness value (e.g. as mg/ L of calcium carbonate (CaCO3) is calculated using the following equation:
Total Hardness as (mg/ L as CaCO3) = 2.497 x [Ca (mg/L)] + 4.188 x [Mg (mg/L)]
Water Hardness Scale [mg/L or parts per million (ppm)]
Note: Hardness is also reported in units referred to as Grains per Gallon (GPG). To convert a hardness concentration from GPG to ppm, simply multiply GPG x 17.1=ppm.
Though sodium in your drinking water is not a health risk, it may become undesirable in higher concentrations. Large amounts of sodium in your water can affect the taste and may become a problem over time for those on a low-sodium diet. Sodium in your drinking water most commonly comes from natural deposits in the ground and water runoff near roads where de-icing salts are commonly used. The EPA DOES NOT have an enforceable maximum contamination level or action level for sodium in drinking water is but the health advisory for sodium is 20 mg/L.
Barium is a less-common contaminant in drinking water which can have adverse health effects after long-term exposure. Most commonly, barium contamination comes from the erosion of natural deposits in the ground but can also be traced back to industrial runoff such as refinery waste and oil and gas drilling discharge. The EPA maximum contamination level or action level for barium in drinking water is 2 mg/L.
Nickel is a less common but serious drinking water contaminant which can lead to severe health effects with high exposure. The most common sources of this contamination are industrial runoff near factories or mines and sometimes leaching from severely corroded plumbing. Nickel is also found naturally in deposits in the ground which can lead to some contamination. The EPA maximum contamination level or action level for nickel in drinking water is 0.100 mg/L.
Zinc is a less common drinking water contaminant which in low concentrations can lead to a metallic taste in your water and in high concentrations can lead to some adverse health effects. Most commonly this type of contamination comes from the corrosion of galvanized plumbing but can also leach into groundwater drinking sources from industrial runoff. The EPA maximum contamination level or action level for zinc in drinking water is 5 mg/L.
Though nitrate and nitrite are technically two different contaminants, they are tested for together because of the nature of their similarity. Nitrite is the first product of the oxidation of ammonia, and nitrate is produced when nitrite is further oxidized in this process. This process is most initiated by bacteria present in soil, which in combination with other sources such as agricultural runoff where fertilizer has been used, and organic waste and decomposition can leech into drinking water sources. High levels of nitrates and nitrites in drinking water can lead to health complications in severe cases. We commonly test for this analyte in both drinking water and wastewater.
Ammonia contamination in drinking water can lead to taste and odor changes in your water and in higher levels, can interfere with chlorine disinfection, influence the pH, and contribute to increased levels of other contaminants such as nitrate and nitrite. The most common sources of this contaminant include agricultural runoff where certain nitrogenous fertilizers have been used as well as industrial runoff and organic waste. We most commonly test for this analyte in wastewater. There are no EPA maximum contamination level or action level for in drinking water for ammonia.
Phosphorous contamination in water exists in several forms which are measured together at once in a test called Total Phosphorous. The most common source of this contamination is agricultural runoff where fertilizer has been used and failing septic systems. We most commonly test for this analyte in wastewater. If too much phosphorous is released into the environment, resulting algal blooms use up oxygen in the water and release toxins, lowering the quality of drinking water sources. There are no EPA maximum contamination level or action level for in drinking water for phosphorous.
Microorganisms present in water demand oxygen to break down organic matter for energy. This removes oxygen from the water that is needed by aquatic and plant life in the surrounding environment. The amount of oxygen demanded by the organisms in a sample of water is called biochemical oxygen demand (BOD) and carbonaceous BOD measures the demand of organisms which do not consume nitrogenous compounds. This test is done on wastewater samples and serves as an indicator of the amount of organic pollutants present.
Chloride is the negative ion of chlorine and is ap product of natural dissolved minerals which leach into groundwater. Though it is not particularly harmful on its own, the presence of chloride in drinking water can affect the taste of the water, increase corrosivity leading to damaged plumbing, and high levels of sodium chloride salt. This analyte is most tested for in drinking water. There are no EPA maximum contamination level or action level for in drinking water for chloride but there is a secondary limit of 250 mg/L.
Free chlorine is the “good”, “ready to work” form of chlorine responsible for sanitizing our water by killing harmful bacteria and viruses. It is important to monitor the presence of free chlorine to ensure that chlorination systems are functioning as intended. This analyte is most monitored in drinking water samples from systems with active chlorine treatment on.
TSS is a test measuring the amount of undissolved (suspended) particulate matter present in a water sample. The nature of these floating particulates ranges from sediment and algae to other types of waste and pollutants. TSS is an important metric for evaluating the efficiency of wastewater treatment but can also be used to evaluate other types of water samples. There are no EPA maximum contamination level or action level for in drinking water for total suspended solids.
TDS is a test measuring the amount of dissolved matter present in a water sample. These dissolved particles can be organic in nature or, more commonly, dissolved minerals such as salts and some metals. TDS is an important metric for evaluating the efficiency of wastewater treatment but can also be used to evaluate other types of water samples. There are no EPA maximum contamination level or action level for in drinking water for total dissolved solids but there is a secondary limit of 500 mg/L.
TS is a test which measures the total amount of particulate matter present in a sample. In simple terms, it is a combination of the amount of TSS and TDS. It is also an important metric for evaluating the efficiency of wastewater treatment but can also be used to evaluate other types of water samples.
Biochemical Oxygen Demand (BOD) testing is a laboratory measurement used to determine the amount of dissolved oxygen that microorganisms require to break down organic material in a water sample over a specified period, typically five days (BOD₅). This test provides an indicator of the level of biodegradable organic pollution in wastewater, surface water, or industrial effluents. Higher BOD values suggest greater concentrations of organic matter, which can reduce oxygen levels in receiving waters and negatively impact aquatic life. BOD testing is widely used to assess water quality, evaluate treatment plant performance, and support regulatory compliance.
The heterotrophic bacteria enumeration test, commonly reported as the Heterotrophic Plate Count (HPC), is a laboratory method used to estimate the number of naturally occurring bacteria in drinking water that can grow on a nutrient medium under specific incubation conditions. These bacteria are referred to as heterotrophs because they use organic carbon for growth and are widely present in soil, surface water, and distribution systems. The test does not target a specific pathogen; instead, it provides a general measure of the overall bacterial population in the water.
HPC results can offer useful information about the biological condition of a drinking water supply, particularly with respect to treatment effectiveness and distribution system integrity. Elevated heterotrophic bacteria levels may indicate conditions that promote bacterial proliferation or regrowth because of such conditions as such as warm temperatures, high nutrient availability, stagnation (e.g., plumbing pipes), or the loss of disinfectant residual. While HPC bacteria are generally not harmful to healthy individuals, unusually high counts can suggest changes in water quality and may warrant further investigation, especially in settings with vulnerable populations.
Importantly, the heterotrophic plate count test, as it relates to the more well-known Total Coliform/ E. Coli. test is not a direct indicator of fecal contamination or acute health risk, and it does not replace regulatory indicator tests such as total coliform or E. coli. Instead,HPC is best interpreted as a supplemental tool for monitoring microbial activity, evaluating treatment performance, and assessing the potential forvbiofilm formation in pipes. When used alongside other microbiological and chemical analyses, heterotrophic bacteria enumeration can help provide a more complete understanding of drinking water quality and system maintenance needs.
Total coliform enumeration testing is a microbiological method used to determine the number of total coliform bacteria present in a water sample, rather than simply reporting whether they are present or absent. Coliform bacteria are a broad group of bacteria commonly found in soil, vegetation, and surface water. While most total coliform bacteria are not harmful themselves, their presence in drinking water can indicate that the water system is vulnerable to contamination or that treatment and distribution system integrity may be compromised.
Enumeration testing provides a quantitative result as opposed to a qualitative test (Present/ Absent), typically reported as colony-forming units per 100 milliliters (CFU/100 mL) or as a Most Probable Number (MPN/100 mL). Common enumeration methods include membrane filtration (MF), where a measured volume of water is filtered and the filter is incubated on selective media to allow coliform colonies to grow and be counted, and multi-tube fermentation or defined substrate methods that estimate bacterial density statistically. The result reflects the concentration of total coliform organisms in the sample at the time of collection.
Total coliform enumeration is particularly useful in evaluating source water quality, treatment performance, and distribution system condition, especially for recreational waters, surface waters, or system investigations. In drinking water compliance monitoring, however, regulations often rely on presence/absence testing rather than enumeration. Elevated total coliform counts suggest possible contamination pathways, inadequate disinfection, or biofilm growth within plumbing, and may prompt follow-up testing for E. coli, which is a more specific indicator of fecal contamination.
The EPA Total Coliform and E. coli test is a standard microbiological analysis used to evaluate the sanitary quality of drinking water and to identify potential contamination by disease-causing organisms. Total coliform bacteria are a broad group of microorganisms commonly found in the environment, including soil, vegetation, and surface water. While most total coliform bacteria are not harmful themselves, their presence in a drinking water sample can indicate that the water system may be vulnerable to contamination or that treatment and distribution conditions are not fully protective. This Total Coliform and E. coli test is a monthly requirement by Pennsylvania Public Water Suppliers (PA-PWS) as per Pennsylvania Department of Environmental Protection (PA-DEP) regulatory requirements.
The detection of Escherichia coli (E. coli) is especially significant because it is a specific type of coliform bacteria associated with the intestines of humans and warm-blooded animals. Unlike total coliforms, E. coli is considered a direct indicator of fecal contamination, meaning that harmful pathogens such as viruses, protozoa, or other bacteria may also be present. For this reason, the EPA requires that drinking water systems take immediate corrective action if E. coli is detected, as it represents an acute public health concern.
Overall, the Total Coliform/E. coli test provides critical information about the basic microbial safety of drinking water.A negative result suggests that the water is microbiologically safe at the time of sampling, while a positive total coliform result may prompt follow-up monitoring or system evaluation. A confirmed E. coli positive result indicates a more serious contamination event requiring urgent response. When combined with other water quality tests, this analysis helps ensure drinking water remains safe, reliable, and protective of public health.
The EPA Total Coliform and E. coli test is a standard microbiological analysis used to evaluate the sanitary quality of drinking water and to identify potential contamination by disease-causing organisms. Total coliform bacteria are a broad group of microorganisms commonly found in the environment, including soil, vegetation, and surface water. While most total coliform bacteria are not harmful themselves, their presence in a drinking water sample can indicate that the water system may be vulnerable to contamination or that treatment and distribution conditions are not fully protective. This Total Coliform and E. coli test is a monthly requirement by Pennsylvania Public Water Suppliers (PA-PWS) as per Pennsylvania Department of Environmental Protection (PA-DEP) regulatory requirements.
PA Department of Health Requirement: Swimming Lakes (Bathing Places)
In Pennsylvania, natural swimming areas at camps (often called swimming lakes, bathing places, or public bathing waters) are regulated under the Pennsylvania Department of Health (PADOH). The primary bacterial requirement is routine monitoring for Escherichia coli (E. coli). PA DOH requires that swimming lakes be tested for (E.coli) as the standard indicator organism for fecal contamination.
Why PA Requires This Testing
The purpose is to protect campers from illnesses caused by pathogens that may enter lakes through:
1. Wildlife and waterfowl
Testing Frequency (Typical Camp / Swimming Lake Requirement)
For licensed or inspected camp or general bathing places, bacterial testing is generally required at least weekly during the swimming season, and more frequently if conditions warrant (heavy use, storms, suspected contamination). It is highly recommended that camps or places of public bathing/swimming also test:
1. Before opening each season
2. After heavy rainfall or flooding
3. After any illness outbreak or water quality complaint
Action Levels / Closures
PA guidance follows EPA recreational water criteria, where elevated E. coli levels may require:
1. Immediate resampling
Note: Any confirmed fecal contamination is treated as a public health concern.
E. coli is used because it is the most reliable indicator of fecal contamination in recreational waters.
Summary of Pennsylvania Action Levels for E.coli in Swimming Waters
Under 28 Pa. Code § 18.28 (Bathing Beach Contamination),water at a permitted bathing beach (e.g., a lake used for swimming) is considered contaminated for bathing purposes if either of the following bacterial criteria is met:
1. A single sample’s E. coli density exceeds 235 colony-forming units per 100mL (235 cfu/100 mL). A result at or exceeding this level is used as a determination that the water is contaminated, and swimming must be discontinued until the Department of Health determines it is safe again. >235 cfu/100 mLin a single sample usually leads to immediate closure or advisory until follow-up testing confirms safety; or
Both criteria are designed to protect swimmers from water with fecal contamination that increases the risk of gastrointestinal and other illnesses. E. coli is used as the indicator organism because its presence reliably signals fecal contamination and possible pathogen microorganisms.
