Does Your Drinking Water Smell Like a Pool Party?
Here’s Why & What You Can Do About It
Did you see the news about the recent chlorine shortage on the West Coast due to an equipment failure at a chlorine manufacturing facility? I don’t know that it will cause any major issues just yet, but I do get questions all the time about this disinfectant.
PSA Time: It’s important to know that chlorine in clean drinking water doesn’t create an odor. Let’s repeat that. Your tap water should not smell like a pool party.
I get emails all the time from people complaining about a strong chlorine smell in their water. No matter what your water utility tells you, I want you to know it’s not normal.
When you smell chlorine in water, it’s typically due to exceedingly high levels of toxic chemical compounds reacting with the chlorine.
Chlorine is the Goldilocks of water treatment.
You don’t want too much or not enough, you want it just right.
But first, here’s a brief history of tap water treatment to understand the full picture. Your drinking water comes from many natural water sources, such as lakes, rivers, and streams, which generally contain organic matter—leaves, dirt, fish poop, etc.
Chlorination, or adding trace amounts of chlorine to water, is one of the primary water treatment methods we’ve used for more than 100 years to remove the organics (aka dirt and friends). It’s the OG because chlorine is effective at killing harmful organisms like bacteria, viruses, and parasites.
Before chlorination, cholera, dysentery, and diarrhea outbreaks were common in cities across the world. Treating the water helped reduce these health problems, but with the advances came side effects.
A Disinfection Reaction
In the ‘70s, scientists discovered that chlorine (a disinfectant) could react with naturally occurring materials in the water to create what are called disinfection byproducts (DBPs). These are substances that form when the disinfectant reacts with natural compounds in the water.
Many of these DBPs have been shown to cause cancer, including trihalomethanes (THMs), which are a group of chemical compounds. They are also known as total trihalomethanes (TTHMs), which includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.
Today, more than a thousand cities have unsafe levels of TTHMs in their water and they have been detected in drinking water systems in all 50 states.
Any imbalance of THMs means the system is out of balance. These compounds occur when organic matter in the water reacts with chlorine, so essentially the system is not being chlorinated properly, meaning you have too much or not enough.
But many cities don’t get to the root of the problem by finding the source of the organic matter. Knowing what’s in the water can help professionals treat it more effectively instead of creating a chemical cocktail mix.
In the last 40 years, scientists have discovered more than 600 other DBPs in chlorinated tap water, including haloacetic acids. As you can imagine, the water has only become more polluted (with both organic and inorganic substances), creating more treatment headaches and violations.
Burn Baby Burn
Back to the chlorine smell. Sometimes it occurs because the municipality is doing what’s known as a “chlorine burnout” in order for the utility to meet EPA standards.
Let’s look at an example.
Residents from Harris County, Texas, which includes Houston and its surrounding areas with a population of more than 4 million people, started writing to me in 2014 because their tap water had a strong chlorine smell, along with sediment and sludge.
The water utility responded with the following statement:
We are aware of the residents’ concerns. The water has always been safe for human consumption and continues to meet the TCEQ requirements. We have been performing routine maintenance on the system which is required periodically when delivering surface water in large systems. The residents were notified of the routine maintenance through a message on their water bill and by signs posted throughout the district. As part of the process, we have switched disinfectants and have increased our flushing.
The “flushing” they are referring to is a chlorine burnout. The levels of chlorine used in a burnout produces chloroform, which is primarily what you smell. When this substance is inhaled in a hot shower or through medical devices (humidifiers, CPAPs, or nebulizers), it can cause chemically induced asthma and pneumonia.
This rush of chlorine into the system can sometimes contribute to that pool smell. Harris County is just an example. These burnouts are happening everywhere and much more in the summertime as temperatures rise and the threat of added bacteria or buildup in water infrastructure increase.
But there’s also another player you need to know about: ammonia. Many water treatment facilities throughout the country are changing the way they handle drinking water at alarming rates using an alternative disinfectant called chloramine, which is a mixture of chlorine and ammonia. Some estimates show that more than one in five Americans drink water disinfected with chloramine.
One of the main reasons for this switch is to provide increased protection from bacterial contamination. But using chloramine is literally one of the cheapest options available and it’s not as effective at controlling taste and odors in the water.
Chlorine evaporates into the air relatively quickly, while chloramine is more stable and will last longer in the water system. Research has shown that chloramine causes deterioration of the municipal infrastructure thanks to changes in the water chemistry. In water systems that still use lead pipes or lead components, this reaction causes the lead and other heavy metals to leach into drinking water and out of faucets and shower heads.
Instead of spending the money to fix old pipes and update our systems, money-crunched municipalities are adding chemicals like ammonia to drinking water as a quick fix, which only causes more issues, including a chlorine-like stench.
Many municipalities that use chloramine report failure of rubber-made valves, gaskets, and fittings, which are key components in any water treatment system. Yes, it might be a cheap fix, but you get what you pay for.
A better solution is to clean the dirt out of the drinking water and stop adding ammonia to mask the reactions that lead to burnouts. It’s a vicious cycle!
The utility has other options to clean the dirt out of your drinking water, but they won’t use them without pressure from you, the consumers. This is why I keep saying that the consumers must become the regulators.
Solutions Start Here
If you smell chlorine in your drinking water, call your water company. Let them know how long it’s been going on. Do your best to work with your water treatment operators and elected officials to get to the source of the problem.
Talk to your neighbors and see if the problem is happening throughout the neighborhood or just at your house. If it’s an ongoing issue, take it to the city council and bring water samples. Research everything you can about how the water is treated and get a copy of your water report. Be persistent and don’t give up!
If you have tried everything and just want to know more about how to filter the water at your house, see my thoughts here. Plus, you can learn a lot more about ammonia and other water problems in Superman’s Not Coming.
Have you had issues with your tap water smelling like chlorine? Sound off in the comments below.
Well, HELLO, everyone! Yes, these problems are everywhere... ugh. Thanks for writing in and I hope you will try some of the steps we've talked about above. Forgot to mention EPA guidelines say chlorine should not exceed 4PPM in your water: https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations#Disinfectants
Water reports come out every July, so be sure to review them and call your utility with questions/concerns!
Hello, I am an Automation Engineer and have worked on large scale water treatment projects. Though this experience I learned a lot about water treatment and as I now know too much I do not drink tap water ever. This is because I have worked with water treatment plants and operators and have learned that they are not at all on top of what they are putting out. They go through the motions to satisfy EPA requirements for testing but rarely give a damn what they are doing. They are bored to death sitting in a treatment plant for hours and frequently over or under feed the chemicals.
I have always been suspicious of tap water causing cancer over prolonged periods of exposure and consumption. Trihalomethanes are not easily monitored real time and yes Erin, these problems are nationwide. There is a long list of problems associated with municipal drinking water supplies and unfortunately money does the talking when it comes to how much effort they put into ensuring that it is safe for general consumption. It is too complicated for the average citizen to understand without going through some education on it. As part of my experience I got a Water Treatment Plant Operator Certification and have been involved in programming and design of the automated systems that run these facilities.
The controls are not always well maintained or calibrated, and a chlorine analyzer out of calibration can cause a gross misfeed of chemicals that can lead to many problems. They add a lot of things to the water from polymers that aid in the filtration process, chlorine, and other chemicals that coat the pipes to aid in flow and corrosion prevention. Then you drink and cook with it.
I've also been involved in air quality automation with the California Air Quality Management District (AQMD) and the refineries but that's a topic for another post.