The Safe Drinking Water Act: What You Need to Know

The Safe Drinking Water Act of 1974 is a federal act that gives the EPA authority to place standards on contaminants found in drinking water

Updated: June 24, 2023
Jeremiah Zac


There are over 148,000 public water systems currently operating in the United States and providing water to people. In order to ensure safe water consumption, environmental regulations such as the Safe Drinking Water Act (SDWA) help keep contaminants in the public water supply at a level that is safe for humans.

This article will break down the different contaminants the SDWA regulates and discuss the history of its inception. We will also cover some important aspects of the SDWA including bottled water and how private water systems are affected.

History of the Safe Drinking Water Act

Summer, N.Y. / Bain News Service / Library of Congress

Throughout history, the establishment and growth of civilizations were largely dependent on their proximity to a clean water source. Without a sustainable water source, cities and towns are unable to develop the irrigation and wastewater systems required to support the needs of a growing population.

But as societies develop, many of the water sources run the risk of being contaminated with the waste and byproducts of the industries involved in keeping society afloat. Rivers often turn into dumping grounds for chemicals and human waste.

The development of the Safe Drinking Water Act of 1974 is not unlike this story.

The American Industrial Revolution: More Water, More Problems

As the American population exploded during the industrial revolution, more elaborate infrastructure was created to meet the rising demand for water among the vast population in cities. For the first time, city dwellers began to experience luxuries such as toilets, faucets, and indoor plumbing.

But the comfort and standard of living that these water systems brought also came with their own set of unforeseen drawbacks. Sewage and waste from homes began to overrun the water systems and pollute the clean water sources. By the late 1800s, waterborne diseases like Typhoid fever and cholera became rampant in metropolitan cities like New York and Philadelphia.

Consequently, in order to manage these waterborne epidemics, water treatment facilities were created to ensure clean drinking water via disinfection means such as chlorination and UV purification.

To ensure that state and local governments ensure clean water measures for the public water supply, various policies were adopted over the course of the next several decades.

But it wasn’t until 1974 that a comprehensive, unified set of federal standards were put into place.

What is the Safe Drinking Water Act of 1974?

Safe Drinking Water Act / EPA

The Safe Drinking Water Act is a federal policy that gives the Environmental Protection Agency (EPA) the jurisdiction to set minimum standards for water quality that local governments should abide by in order to ensure the safety of the public.

The EPA separates its regulation standards into two categories: Primary Standards and Secondary Standards.

National Primary Drinking Water Regulations (NPDWR) hold to the highest standard and focus on contaminants that are considered directly harmful to humans if consumed.

National Secondary Drinking Water Regulations (NSDWR) are slightly less stringent and focus on contaminants that affect the aesthetic properties of water such as color, taste, hardness, and turbidity.

There is also a category of no standards where no formal Primary or Secondary standards are applied.

Each contaminant has a certain level of concentration that the EPA deems safe. If the level of concentration rises above these standards, anyone consuming the water may be at risk and the governing body will be in violation.

National Primary Drinking Water Regulations

Contaminants that fall under the NPDWR are considered primary contaminants and have a direct impact on one’s health if consumed beyond the set standards.

The EPA further categorizes primary contaminants into the following groups:

  • microorganisms
  • organic chemicals
  • inorganic chemicals
  • disinfectants and disinfectant byproducts
  • radionuclides


Microorganisms are biological contaminants in water that can cause major illness if consumed. Common microorganisms are viruses such as norovirus or hepatitis A; bacteria such as cholera, typhoid, e. coli, or salmonella; or protozoa such as Cryptosporidium or Giardia.

View the microorganisms table

Inorganic Chemicals

Inorganic chemicals are a class of substances that lack carbon atoms in their molecular structure. These chemicals can be naturally occurring or artificially introduced into water sources and have the potential to pose risks to human health if present above the regulated levels.

While some inorganic chemicals aren’t necessarily harmful if consumed at low levels, others such as arsenic should be avoided.

View the inorganics table

Organic Chemicals

While the term “organic” can be misleading, organic chemicals refer to a broad category of substances that do contain carbon atoms in their molecular structure. These compounds can come from various sources, including industrial processes, agricultural activities, and can also be found naturally in surface water and groundwater.

Human consumption of organic chemicals can cause various health problems depending on the concentration and duration of exposure.

Organic chemicals can be further broken down into VOCs and SOCs.

Volatile Organic Chemicals (VOCs)

VOCs are a subset of organic chemicals with properties that make them convert easily into gas at room temperature—they can come from a wide range of sources, such as solvents, fuels, and certain industrial processes.

Exposure to VOCs, either through inhalation or ingestion, can have adverse health effects on humans, including respiratory irritation, organ damage, and an increased risk of certain cancers.

Common VOCs include benzene, toluene, and formaldehyde.

Synthetic Organic Compounds (SOCs)

SOCs are man-made organic chemicals often associated with industrial activities, manufacturing processes, and the use of certain chemicals and pesticides, also known for causing major health issues if consumed.

Examples of SOCs include polychlorinated biphenyls (PCBs), dioxins, and certain pesticides like atrazine and lindane.

View the organics table

Disinfectants and Disinfection By-products

Disinfectants are substances used to destroy harmful microorganisms in water and are an important tool in ensuring public health by preventing the spread of waterborne diseases.

Common disinfectants used in water treatment include chlorine, chloramines, ozone, and ultraviolet (UV) light. Because disinfectants themselves can cause health problems if consumed at high concentrations, they too must adhere to EPA standards and are carefully measured when applied to water treatment processes.

The use of disinfectants can also result in the formation of unintended contaminants known as disinfection byproducts (DBPs) when disinfectants react with naturally occurring organic and inorganic matter in water. Some common DBPs include trihalomethanes (THMs), haloacetic acids (HAAs), and bromate, and are known to cause health problems when consumed at elevated levels.

View the disinfectants table

Radioactive Isotopes

Radioactive isotopes are atoms that emit radiation as a result of radioactive decay.

Certain elements such as uranium, thorium, and radium can exist naturally in rocks and soil, potentially dissolving radioactive isotopes in groundwater or leaching into surface water.

Human activities can also introduce radioactive isotopes into water sources through nuclear power plants, research facilities, and radioactive waste disposal sites, releasing radioactive materials into nearby water bodies, either intentionally or through accidents and leaks.

While naturally occurring, trace levels of radioactive isotopes will be present in many water sources, prolonged exposure to high levels of radiation from radioactive isotopes can be damaging to living tissue.

View the radioactive isotopes table

National Secondary Drinking Water Regulations

National Secondary Drinking Water Regulations (NSDWRs) are non-mandatory water quality standards for 15 contaminants. These regulations differ from primary standards in that they are not based on health considerations but on aesthetic, cosmetic, or technical issues associated with drinking water.

Aesthetic concerns revolve around properties of water that affect consumer senses—like taste, odor, or color—while cosmetic effects relate to potential skin or tooth discoloration.

Technical effects usually involve damage to water equipment or reduced effectiveness of treatment processes for other contaminants due to the water’s characteristics.

Although these standards are not federally enforceable, the EPA recommends that all water systems serving the public meet these guidelines to enhance customer satisfaction and protect the infrastructure of water systems.

View Secondary Contaminants table

What You Need to Know


The SDWA contains a right-to-know provision that states that the recipients of the public water supply must be informed should any contaminant exceed the SDWA standards at any time. Should a local utility fail to inform the public, it would be in violation of the SDWA and subject to intervention or fines.

Private Wells

One important aspect of the SDWA is that it only covers public water systems, but isn't enforced on private water systems such as a private well.

So what is considered a public water system?

Public supply refers to water withdrawn by water suppliers that provide water to at least 25 people or have a minimum of 15 connections.

The USGS estimates that more than 43 million people—about 15 percent of the U.S. population—rely on domestic (private) wells as their source of drinking water.

This means that those who rely on private water systems are responsible for testing and filtering their own water supply.

Bottled Water

Because bottled water is a commodity that is privately owned and sold, it isn’t regulated by the EPA but by the FDA.

In fact, the FDA has slightly less stringent standards than the EPA when it comes to water contamination.

This means that there are some bottled water brands that may actually contain more contaminants than some tap water sources. In fact, some brands are known for simply bottling water at a public water utility and not from a spring or mountain source.

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I'm Jeremiah, the owner of World Water Reserve. I'm a writer and researcher with a particular interest in sustainability and rural living, water scarcity, and innovative water purification methods. I utilize my multimedia and communication experience in the NGO and humanitarian fields to bring light to important topics. My passion is to educate others on the reality of the global water crisis and on ways to sustain themselves and their families in the midst of it.
Jeremiah Zac