What are Disinfection Byproducts (DBPs) in Drinking Water?

Every day, swarms of waterborne microbes infiltrate our drinking water systems – E. coli bacteria, brain-eating amoebas, the whole shebang. Because of this, the EPA requires all public water utilities to take steps to ensure only clean, microbe-free drinking water reaches our homes. But in most cases, these measures include adding chlorine to the water.

Sure, chlorine does a remarkable job of preventing microbial contamination in water and protecting people from potentially deadly waterborne diseases and illnesses. But despite its extraordinary water disinfecting abilities, chlorine (and other chemical disinfectants) can create hundreds of potentially dangerous compounds in water called disinfection byproducts (DBPs).

If you have a strong science background or you’ve been an avid reader of our blog, you might know what DBPs are, how they form, and how they can affect the quality of your drinking water and your health. But if not, this article explains everything you need to know about DBPs, including the most common ones in tap water and a simple and effective method to eliminate them from your water supply. Let’s start by looking at what DBPs are.

What are Disinfection Byproducts?

If your water comes from a municipality, it’s most likely treated with chlorine before reaching your home. Unfortunately, chlorine (a disinfection chemical) can interact with other compounds in the water to form disinfection byproducts (DBPs).

DBPs are chemicals and organic and inorganic compounds that form when a disinfection product (chlorine, in this case) reacts with natural organic matter (NOM) in water.

The factors affecting the number and concentration of DBPs formed include:

  • the amount of chlorine used,
  • the water’s organic matter content,
  • the contact time between the organic substances and the chlorine,
  • the acidity of the water, and
  • the water temperature

Usually, the higher the values of these factors, the more DBPs are formed and the higher their concentrations.

How Are People Exposed to DBPs?

There are three main ways DBPs can get into your body:

  1. Through inhalation: If your water supply contains DBPs, some of the chemicals can release into the air inside your home when you use your tap water – when you take a bath or shower, pour water from the tap into your drinking glass, or wash the dishes or laundry. Usually, the hotter the water is, the more likely DBPs will be released into the air. DBPs can also get into the air when you boil tap water, for example, when making tea or soup.
  2. Through the skin: You can also be exposed to DBPs when your skin comes in contact with affected water, such as bathing, showering, or swimming in a pool containing harmful byproducts. While only minimal amounts of DBPs enter the body through the skin in most people, much higher levels can enter your body when your contact time with the DBPs-tainted water increases. This can happen if you take long baths or showers or regularly swim in public pools.
  3. Through ingestion: The primary source of exposure to DBPs is ingestion (i.e., drinking the water and ingesting it in foods and ice prepared with the water). Some DBPs may be present in unfiltered tap water used for drinking. Some people claim they can taste the difference when these byproducts are present, but many continue drinking the contaminated water.

How Do DBPs Get into Drinking Water?

According to the Minnesota Department of Health (MDH), “The formation of DBPs is usually a greater concern for water systems that use surface water, such as rivers, lakes, and streams, as their source. Surface water sources are more likely to contain the organic materials that combine with chlorine to form DBPs.”

Since about 70 percent of freshwater used in the United States comes from surface water sources, millions of Americans are likely at risk of being exposed to DBPs – well, at least those without a proper home water filter system to remove the disinfection agent and its byproducts.

But how do DBPs form in water in the first place, let alone get into tap water? The process is pretty straightforward:

  1. NOM, such as decaying leaves and decomposed plants and animals, wash from the surrounding soil and rock into rivers and reservoirs used as water supplies.
  2. Water treatment plants filter the water from these sources to prepare for disinfection, but not all NOM gets filtered out.
  3. Municipalities add chlorine to the water to destroy microbes, such as bacteria, viruses, parasites, etc.
  4. The chlorine reacts with the leftover NOM to create DBPs.
  5. The DBPs enter the public distribution system, travel along pipes and plumbing into your home, and contaminate your water supply.

DBPs can also form in chlorine-disinfected well water systems. The risk may be considerably higher with well water since private wells aren’t regulated and, therefore, are not required to be filtered to remove NOM (or any other contaminant, for that matter).

Also, some DBPs are used in industrial applications or wastewater treatment processes and may be present in groundwater or surface water from these sources. Since water wells – specifically those constructed near rivers, streams, or drainage ditches – are more prone to flooding, higher levels of organic matter could leach into the well system.

Without a reliable home treatment system to reduce the DBPs concentration in water, more NOM and chlorine can cause the chlorine reactions to be more vigorous and productive, creating even more byproducts.

Common DBPs in Tap Water and Their Potential Health Risks

Depending on the substances in the water, the reactions can create a wide variety of byproducts. While experts have identified over 600 disinfection byproducts, the most commonly found DBPs are trihalomethanes, haloacetic acids, bromates, chlorites, and chlorates. We describe each in more detail below.

1.     Trihalomethanes (THMs)

Trihalomethanes (THMs) are a byproduct of the chlorination of water containing naturally occurring dissolved organic matter. The four trihalomethanes commonly found in chlorinated drinking water are:

  • Trichloromethane (chloroform)
  • Bromodichloromethane (BDCM)
  • Dibromochloromethane (DBCM)
  • Tribromomethane (bromoform)

THMs are among the most dangerous DBPs created by chlorine in the water. Research shows that consuming water with THMs or inhaling them can lead to serious health complications, such as stillbirths, congenital disabilities, increased risk of kidney and liver cancer, and issues with the central nervous system, heart, kidneys, and liver.

Inhaling THMs and chlorine can be more dangerous than consuming them because both chemicals convert into vapor at a lower temperature than water. That means taking a shower in chlorinated water can increase exposure to these toxic chemicals.

And when we think it couldn’t get any worse, a 2005 academic article stated that THMs are more concentrated in the body when absorbed through the skin than drinking tap water that contains the chemicals. These toxic DBPs not only affect your health when you drink tap water but might be a significant risk every time you shower.

Other scientific literature reports linkages between DBPs and congenital disabilities, fetal developmental delays, and adverse developmental or reproductive effects in humans. Some studies indicate a link between high levels of trihalomethanes in drinking water and early-term miscarriages.

2.   Haloacetic acids (HAAs)

Like trihalomethanes, haloacetic acids (HAAs) are a disinfection byproduct. The five most common haloacetic acids found in water are:

  • monobromoacetic acids
  • dibromoacetic acids
  • monochloroacetic acids
  • dichloroacetic acids
  • trichloroacetic acids

These compounds will also form when wastewater sources, such as sewage effluent, are disinfected.

Haloacetic acids in water are dangerous. Their most prominent health effect is an increased cancer risk. The EPA reports that prolonged exposure to haloacetic acids in water makes people vulnerable to developing cancer.

However, other studies suggest that HAA exposure in water – while showing an increase in the development of liver tumors and liver cancer – has thus far only occurred in animals. Despite this, there’s still the likelihood of HAAs causing cancer in humans, so try your best to avoid excessive levels of haloacetic acids in drinking water.

Studies also link HAAs exposure to an increased risk of congenital disabilities. Although no extensive studies show that humans are affected, studies on rats have demonstrated poor fetal growth and higher incidences of malformed hearts and kidneys when pregnant rats have been exposed to high doses of HAA.

Another possible health effect of haloacetic acids in water is severe irritation to the skin and eyes. Both short- and long-term exposure to high levels of HAAs can cause inflammation, skin loss, and damage to the structural protein collagen in the skin’s connective tissues. In some cases, skin damage can last from 2 to 15 weeks.

3.   Bromates

Bromates are created when naturally occurring bromides react with various disinfectants in the source water. For instance, when ozone (another disinfectant) reacts with bromide ions, bromates will form in the water. They can also develop as a byproduct of bromate hypochlorite oxidized by bright sunlight, such as in uncovered swimming pools, tanks, or drinking water reservoirs.

The New York State Department of Health found that adults who consume approximately two quarts of bromate-contaminated water daily would only increase their risk of cancer by two in ten thousand. However, it also warns that women of childbearing age and children may experience increased cancer rates from long-term exposure to bromates in drinking water.

Ingesting large amounts of bromates can have adverse health effects similar to those that disinfectants added to public water seek to reduce, such as vomiting, diarrhea, abdominal pain, nausea, kidney problems, nervous system issues, and hearing loss. There are some concerns that people with preexisting kidney conditions may be more susceptible to the side effects of bromates.

4.   Chlorites and Chlorates

These DBPs form when chlorine dioxide is used to disinfect and control the odor or taste of drinking water. Chlorine dioxide is also commonly used to remove iron, manganese, and colors from the water.

When people ingest chlorite and chlorine dioxide, even at relatively low dosages, they increase their risk of developing respiratory issues, a reduction of the ability of the blood to carry oxygen, inhibited human development in infants or human fetuses, and irritation to the gastrointestinal system.

So, Why Don’t Municipalities Use Disinfection Methods That Don’t Create These Byproducts?

Chlorine and other chemical disinfection products are relatively cheap, effective, and widely available, so municipalities prefer to use them. But all these chemical disinfectants share a common trait: they create byproducts – and as you’ve read above, exposure to these compounds can be dangerous. Then why don’t water treatment facilities switch to methods that don’t form byproducts? Excellent question, but it’s not that simple.

Some utilities have adopted non-chemical disinfection methods, such as ultraviolet light and reverse osmosis (RO). However, these methods are usually expensive to implement and maintain on a broader scale.

They also do not solve the problem of disinfecting the water after it leaves the plant, as microbes can still enter public water lines through leaks, water main breaks, etc., and re-contaminate the water before it reaches your home.

Utilities with UV and RO systems may add small amounts of disinfectant to the water as a final treatment step before distribution. Still, the problem of byproducts may remain – perhaps not as much as using all-out chlorination, but the danger will likely persist.

How Are DBPs Regulated in Drinking Water?

The EPA’s Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR) outlines the Maximum Contaminant Level Goals (MCLGs) in milligrams per liter (mg/L) and Maximum Contaminant Levels (MCLs) in (mg/L) for various DBPs found in tap water.

The table below shows a list of the DBPs discussed in this article and their associated MCLGs and MCLs.

Disinfection Byproduct MCLG (mg/L) MCL (mg/L)

–         Bromodichloromethane

–         Bromoform

–         Dibromochloromethane

–         Chloroform





Haloacetic acids

–         Dichloroacetic acid

–         Trichloroacetic acid

–         Monochloroacetic acid




Bromate zero 0.010
Chlorite 0.8 1.0


Does Your Drinking Water Contain DBPs?

If your drinking water is treated with chlorine, chlorine dioxide, fluorine, or bromine, there’s a good chance your water contains HAAs, THMs, bromates, chlorites, or chlorates. It’s even more likely if your water source is surface water. However, there are a few methods you can use to be sure if your water is tainted with DBPs:

  1. Enter your zip code in the EWG’s Tap Water Database to determine what toxins could be lurking in your tap water.
  2. Contact your water utility or state public health agency and request their most recent water quality report. Many DBPs are monitored regularly in all water systems that use chemical disinfectants, and by law, regulated water utilities must make the composition of your water available to you. You can find your water system’s DBPs monitoring results in said report.
  3. Order a water testing kit that requires you to prepare a water sample at home and submit it to a certified lab. By utilizing a lab, you have the assurance that a certified water expert will analyze your water sample and provide the most accurate results possible.

If any of these methods indicate that your water contains DBPs (use the chart above to compare them to the EPA recommendations), continue reading to determine the best treatment method.

How Does Springwell Protect You from Potentially Harmful DBPs in Drinking Water?

Reducing DBPs in water requires a method that can effectively protect against infection from microbes while minimizing the health risks from DBP exposure. Chlorine and other water disinfectants are valuable in treating microbial contaminants in water at the municipal level. But as we become more aware of DBPs and their potentially severe health effects, we must weigh the risks and hazards of DBPs against the benefits of chemical disinfection.

Based on the dangers of chlorine and DBPs in drinking water, we suggest an additional safety measure, like installing a professional-grade home water filter system. Springwell’s whole-house water filters combine activated carbon filtration, mechanical filtration, and other features and technologies to filter out up to 99.6 percent of common contaminants in water. These pollutants include chlorine, chloramine, bad taste and odors, THMs, HAAs, etc.

Our activated carbon whole-house systems also remove other common water contaminants, such as lead, copper, mercury, PFAS, pesticides, herbicides, sediment, pharmaceuticals, etc. And the result?

  • Cleaner water that tastes and smells great
  • Healthier, more flavorful foods and beverages
  • Softer skin and healthier hair
  • More enjoyable baths and showers
  • Added protection against potentially dangerous waterborne microbes (with our powerful UV Water Purification System add-on)
  • Better overall health and wellbeing

What’s also great about our whole-house units is that they provide 360-degree protection against chlorine and DBPs at every faucet in your household, whether in the kitchen, laundry room, or bathroom.

Furthermore, when you purchase any of our whole-house filtering systems, there’s a six-month money-back guarantee to allow you to return it and get your money back. Additionally, each system is covered with a manufacturer’s lifetime warranty against defects throughout its lifespan under regular application, service, and use.

If you are interested in a premium and affordable water filter system to protect your drinking water from chlorine, chlorine byproducts, or other waterborne contaminants, please check out our water filter systems or contact us.

Final Thoughts

DBPs are present at some level in every public water system in America. And as you’ve learned in this article, they can be very dangerous, especially when ingested. DBPs can cause serious health effects, from congenital disabilities to kidney and liver cancer.

The safest and most reliable solution to reduce chlorine and DBPs in drinking water is to install a whole-house water filter system with a UV post-filter to eliminate microbes that may have entered the water after leaving the treatment plant.

Thankfully, Springwell’s water filter systems can significantly reduce chlorine and the formation of THMs, HAAs, and other DBPs in water. When paired with our UV purification system, these systems protect you against 99.9 percent of bacteria, viruses, and other microbes in water.