The Center for Disease Control and Prevention (CDC) estimates that 1.1 million people in the United States get sick every year from germs in drinking water. Although water treatment vastly decreases the number of people who get sick from drinking water, tap water can still get contaminated with harmful germs and chemical, making people sick. NSF/ANSI/CAN 600-2024: Health Effects Evaluation and Criteria for Chemicals in Drinking Water defines how to assess the toxicity of substances that may contaminate drinking water.
What Substances Are Hazardous in Drinking Water?
Drinking water sources (e.g., rivers, lakes, reservoirs, and groundwater aquifers) may contain a variety of contaminants, such as:
- Inorganic chemicals (e.g., lead, arsenic, nitrates, and nitrites)
- Organic chemicals (e.g., atrazine, glyphosate, trichloroethylene, and tetrachloroethylene)
- Microorganisms (e.g., E. coli, Giardia, and noroviruses)
- Chemical elements (e.g., mercury and radium)
- Pesticides (e.g., alachlor, simazine, and diuron)
- Disinfection byproducts (e.g., chloroform)
- Heavy metals (e.g., cadmium and chromium)
- Emerging contaminants [e.g., Per- and polyfluoroalkyl substances (PFAS)]
These contaminants can cause a range of health issues including cancer, developmental problems in children, kidney damage, liver damage, and reproductive issues. Hence, due to their toxicity, they can pose significant adverse health effects. Luckily, documents like NSF/ANSI/CAN 600-2024 exists, which details methods for how to evaluate contaminants in drinking water,
What Is NSF/ANSI/CAN 600?
NSF/ANSI/CAN 600-2024 defines the toxicological review and evaluation procedures for the evaluation of substances imparted to drinking water through contact with drinking water system components (and drinking water additives). This American National Standard aims to establish the human health risk, if any, of the substances imparted to drinking water under the anticipated use conditions of the product.
Table 4.1, Drinking Water Criteria, contains evaluation criteria that have been determined according to the requirements of this standard. Further, the drinking water criteria provided in NSF/ANSI/CAN 600-2024 should be used as evaluation criteria for the determination of product compliance to the health effects requirements of drinking water standards in which this standard is cited, including NSF/ANSI/CAN 60 and NSF/ANSI/CAN 61.
Our blog posts NSF/ANSI 60-2024: Drinking Water Chemicals Health Effects and NSF/ANSI 61-2024: Drinking Water System Components – Health Effects explain these standards in more detail.
Disinfecting Drinking Water
In the early 1900s, communities across the United States began to consistently treat tap water in order to remove harmful germs and chemicals. Since the 20th century, major advances have occurred in regards to disinfecting drinking water to reduce water-borne infectious disease. In fact, that all of the water that comes into your home, whether it is for your sink, shower, toilet or outdoor faucet, is treated drinking water.
The method by which infectious agents are removed or chemically inactivated depends on the type and quality of the drinking water source entering the treatment plant as well as the volume of water to be treated. The rigorous water treatment process begins when water is taken from a water source and then brought to a treatment plant, and the following treatment methods can be utilized:
- Coagulation: Chemicals called “coagulants” are added to water to destabilize and clump together tiny suspended particles, like dirt and bacteria, into larger masses called flocs.
- Flocculation: As the negatively charged particles and positively charged coagulants combine, they form larger particles known as floc. The flocs are then removed from the water, making it easier to treat.
- Sedimentation: This process removes solids (accumulated sludge) that float and settle in the water.
- Disinfection: After the water has been clarified, the water undergoes a two-step disinfection process to prevent infectious disease from spreading and to assure water is safe for people and the environment. The first step is ozone disinfection and the second step is chlorine disinfection.
- Filtration: As a final step in the water treatment process, this process removes solid particles, like sediment, bacteria, parasites, and other contaminants from water by passing it through a porous material that allows the clean water to flow through while trapping the unwanted particles. This step essentially purifies water by physically separating solids from the liquid phase using a filter medium.
This treated water is then collected and can flows into a pump station at a water treatment plant, where it is released to into local waterways to be used for drinking. Here, cities can also perform their own water quality testing, additional maintenance procedures, and compliance to standards like NSF/ANSI/CAN 600-2024 to assure the highest drinking water quality free of contaminants.
NSF/ANSI/CAN 600-2024: Health Effects Evaluation and Criteria for Chemicals in Drinking Water is available on the ANSI Webstore.
This American National Standard was developed and published by NSF International. If you have any technical questions regarding this standard, please contact NSF. Standard developer contact information can be found at Who to Contact for Standards-Related Questions.