What is Water Testing?

Oct. 26, 2022
Explore how water testing works, why water is tested, the common contaminants that are tested for in water and more.

Water testing may be carried out on any occasion when specific water parameters need to be monitored, such as temperature, pH, hardness and potential contamination. 

In this guide, you’ll find information on how water testing works (including the different types of testing), why water is tested, the common contaminants that are tested for in water and more. 

How Does Water Testing Work?

Some facilities may be able to test their water on-site using simple applications. For instance, a built-in thermometer can be used to monitor water temperature, and lateral-flow testing can be used to detect some kinds of bacteria on-site. 
The most common water testing method, however, involves taking a sample of water and sending it to a laboratory for an in-depth analysis. 

Different Types of Water Testing

There are two possible types of water testing: laboratory testing and DIY testing with a kit.  Laboratory testing takes place in a laboratory. A water sample is sent to the lab, where scientists test for specific water parameters. The water is delivered back to the source within two weeks.  DIY test kits usually contain test strips and a color chart. A test strip is dipped in a water sample. The strip changes color to indicate the contaminants present, and the strip is compared to the color chart to determine the level of contamination.  Lab testing is more expensive than DIY testing, but it produces more thorough, accurate and reliable results. 

Importance of Water Testing

Why is water testing needed? 
  • Depending on who is testing the water, water testing may be needed for the following reasons: 
  • To ensure water is safe to drink
  • To ensure compliance with local or national guidelines
  • To determine the effectiveness of water treatment
  • To monitor changes over time
Contaminants Commonly Tested For in Water
Some of the contaminants commonly tested for in water are: 


Drinking water treatment facilities must routinely test their water supplies for microorganisms. Bacteria, viruses, and other pathogens present in treated water indicate that there is an issue with the treatment process or that the system has become infected by local pollution. Microorganisms are dangerous to drink in water, and the EPA closely regulates these contaminants in local drinking water supplies. If microorganisms are detected, the facility must issue a boil water notice and treat its water accordingly. 

Lead & Heavy Metals

Lead is most commonly found in old lead water service lines. Water treatment facilities have no control over how much lead enters customers’ drinking water as it travels to their homes. 
According to the EPA, there is no safe amount of lead in water. Many homeowners test their water for lead with the intention of installing a lead removal filter if this metal is detected. 
Other heavy metals may also be tested for alongside lead to determine the water source’s overall metal parameters, indicating system integrity and water quality. 


Water pH is an indication of overall water quality. Water with a low pH (or acidic water) is corrosive, and is more likely to leach metals from pipes than neutral or slightly alkaline water. Due to its corrosive properties, acidic water damages plumbing and appliances, and may leave blue or green stains. Large-scale and small-scale testing is used to detect water pH levels, depending on the water source and the purpose of testing. 

Physical Parameters

Another good way to determine overall water quality is to test for physical parameters, including suspended and total dissolved solids (TDS). Water with a high TDS count is likely to be more heavily contaminated and of poorer quality than water with low TDS levels. TDS testing is usually conducted alongside specific tests, such as hardness testing, to determine exactly what contributes to the TDS levels. 

Testing Outcomes

The outcome of a water test will determine whether or not any action should be taken, and what action is suitable. 
If contaminants are detected at a drinking water treatment facility, the facility may have to issue a boil water notice and/or ramp up its water treatment efforts, depending on the source of contamination. 
A well owner who finds contaminants in their water may need to shock their well and/or install a whole-home water filtration system to keep the contaminants at bay.  A homeowner on a city water supply may also decide to install a drinking water filter if they discover trace contaminants, like lead, in their water. 

How Often Should Water Be Tested?

The frequency of water testing depends on the purpose of the testing, and who is testing the water. Water treatment facilities test their water supplies frequently - usually several times per day - to ensure that problem contaminants are effectively removed and to provide evidence of compliance with regulations set by the state and the Environmental Protection Agency. 
Private well owners are recommended to test their water at least once a year for nitrates, total coliform, pH levels, total dissolved solids, and any other contaminants of concern. Well owners should also test their water immediately if local environmental conditions have changed significantly or if a part of the well is replaced or repaired. 
People who receive municipal water have no obligation to test their water at all because they’re not responsible for treating their own water supplies. However, some people like to conduct annual tests anyway to learn about the trace contaminants in their drinking water. 


Water testing is conducted by water treatment facilities, private well owners, and homeowners who are simply curious about their water quality. Manufacturers may also test the water used in products in the food and cosmetic industries. 
Testing is important to ensure that water is fit for its intended purpose (usually drinking). Frequently testing water allows various water parameters to be monitored, including temperature, pH, and contamination.
About the Author

Brian Campbell

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