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July 2024

Different Types of Water Quality Testing

Most contaminants in drinking water have no taste or odor and must be tested professionally to identify them. This includes chemicals like volatile organic compounds (VOCs) such as benzene, carbon tetrachloride, toluene, and methyl tertiary butyl ether. To learn more, visit Water Quality Testing Near Me.

Home InspectionTesting is essential for homeowners who use private wells or cisterns. It’s also helpful for urban areas prone to contamination from outdated municipal plumbing, nearby fracking and mining activities, or livestock farming.

What is Water Testing?

There are a wide variety of water tests that can be used to measure different aspects of water quality. Some of these tests are designed to identify specific contaminants or problems while others test for more general parameters. Some are measured in concentration units, such as milligrams per liter (mg/L), which is equivalent to parts per million (ppm). Other measurements use index numbers that are not directly related to concentration, such as pH.

Water quality testing is a critical process to ensure safe drinking water. Whether a water supply is municipal or private, it must be regularly tested to ensure that the chemical, physical, and biological properties are within acceptable limits. This helps ensure that people drink healthfully, businesses operate without impediments caused by off-spec water and the natural environment thrives unhindered by harmful pollutants.

Some of the more common water quality parameters include turbidity, hardness and conductivity, pH and total dissolved solids (TDS). Turbidity is a measurement of the amount of particulate material in the water that makes it cloudy or murky. This material can hide waterborne microorganisms, shield them from disinfection processes and absorb heavy metals. High turbidity can also lead to the presence of unpleasant odors or tastes.

Hardness is a measurement of the concentration of dissolved minerals in the water. Excessively high levels can cause mineral buildup in hot water pipes, a dry feeling to the skin and a metallic taste. High hardness can also interfere with the ability to produce a lather with soap.

Most of the contaminates that can affect water quality are not visible to the naked eye, so they need to be tested for with lab equipment or at-home kits. The lab testing method is more accurate but takes longer to complete than home tests.


Conductivity measures the ability of water to transmit an electrical current. It is a non-selective measurement, meaning that it does not differentiate between different concentrations of ionic chemicals in solution. However, it is easy to read with a conductivity meter and provides information about the total number of ions present in the sample. Increasing conductivity levels in lakes and rivers can indicate pollutants. For example, a sewage leak increases the conductivity level because of the addition of chloride, phosphate and nitrate ions, whereas an oil spill decreases it because these elements do not break down into ions 1.

Conductive measurements can also be used to detect changes in dissolved oxygen levels, as high levels of soluble salts typically lower oxygen levels. In addition, temperature and salinity influence the conductivity of water. Using an NDSU water quality monitor, you can quickly measure the total dissolved solids (TDS) and conductivity of a water sample.

Water with a higher specific conductance will have more ions per volume than less conductive water. The specific conductance of a water is the ratio of conductivity to its molar mass, or molecular weight. The molar mass of pure water is 1 g/cm3.

During a flooding event, conductivity tends to increase due to the influx of nutrient and mineral-rich soil from floodplains. In addition, salt ions that were previously dry in the soil can enter solution as the water enters and increase the conductivity of the floodwaters.

Conductivity readings are often reported at a specific temperature to normalize the results. The specific conductance of a water at 25 deg C is the standard reporting value. This allows data from different locations to be easily compared.

Total Dissolved Solids (TDS)

When water falls on rocks, soil or grass it dissolves some of the minerals and salts contained in those materials. This process, known as leaching, is a natural one. These dissolved solids are called total dissolved solids or TDS.

All types of water contain some TDS, but some sources have higher levels than others. For example, groundwater typically has higher TDS than surface water from rivers or lakes. Bottled mineral water also tends to have high TDS levels.

TDS is measured in milligrams per liter (mg/L) or parts per million (ppm). Generally, a TDS measurement of less than 500 ppm is safe for drinking. A TDS reading of 1,000 ppm or more, however, is likely to indicate the presence of harmful contaminants.

Most people don’t need to measure TDS in their homes, but for those who do, there are a few different ways to do it. One way is to use a lab test, which can be expensive and inconvenient. A better option is to use a TDS meter, which can be purchased for between $10 and $100 depending on the device and manufacturer.

Keeping track of TDS is most useful for those who are struggling with hard water or other water quality issues. For instance, if you are using a water softener to address hardness issues, measuring TDS can help keep track of your progress and help make sure the hard water has been completely eliminated from your water supply. Those with a hot tub or swimming pool may also find it helpful to measure TDS to make sure the water is pure enough for their purposes. This is especially important if they are using metal pipes that may leach some unwanted substances into the water.

Total Coliforms

Biological pathogens (bacteria, viruses, protozoa, or parasites) can be found in drinking water. Often, the source of these pathogens is fecal contamination from animals that have contaminated the environment with their wastes. As a result, the presence of fecal contamination in drinking water can lead to illness or disease outbreaks. However, it is not practical to test for all the possible pathogens in every sample of drinking water taken by a water system. Instead, many systems use “indicator organisms” like coliform bacteria to check for the presence of pathogens in their water samples.

Coliforms are bacteria that are naturally present in the digestive tracts of animals, in animal wastes, and in plant and soil material. They are not harmful in themselves, but they can be a pathway through which more dangerous pathogens can enter drinking water. Testing for the presence of coliforms is therefore an important part of a water system’s effort to produce safe and clean drinking water.

A good treatment system will remove most if not all coliforms from the water it produces at the treatment plant. Therefore, the recommended sampling frequency for coliforms at treatment plants is typically based on the size of the population that the water system serves.

When the coliform levels in a water supply sample are above the minimum acceptable level at a point in the distribution system, then additional actions may be required. These could include warning residents to boil their drinking water before consumption, as well as investigating the source of the contamination and implementing corrective actions.

Storage temperature can have a major impact on the results of coliform tests, so it is critical that samples be stored and transported at the proper temperatures (e.g., below room temperature). Commercial devices are available to verify that a sample is at the appropriate storage and transport temperatures during collection and transit to the laboratory.

Other Germs or Harmful Chemicals

The quality of drinking water can be seriously compromised by the presence of pathogenic (disease-causing) bacteria, viruses and parasites. Drinking water contaminated with these organisms can cause diarrhea, cramps, nausea and other unpleasant symptoms. In the most severe cases, these pathogens can lead to disease and even death.

Microbial contamination contributes heavily to the global burden of human disease and is particularly dangerous for infants, young children and people with compromised immune systems. In fact, contaminated water causes up to 143,000 deaths every year from cholera and other diarrheal diseases such as dysentery, typhoid and hepatitis A.

Bacteria and other organisms that are normally found in the environment can also be introduced into water sources by human or animal activities. This may be the case when sewage or manure from homes, farms and businesses is spilled, leaked or disposed of improperly. In addition, some types of pesticides and solvents can be a source of contamination.

Most of the drinking water in the United States comes from community water systems, which must meet EPA standards. However, about 15 million Americans get their water from private wells. Well owners are responsible for testing their own drinking water and maintaining their wells.

Some of the most common tests are for fecal coliforms and Escherichia coli (E. coli). A positive test result indicates the presence of these harmful bacteria in your drinking water.

Other tests include dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD). The specific chemicals you should test for will depend on where your well is located on your property, which state you live in, and the environmental conditions where you live. For example, industrial and fuel-related contaminants such as cadmium, arsenic, lead, benzene and methyl tertiary butyl ether (MTBE) may be of particular concern in urban areas.