Does Reverse Osmosis Remove Trihalomethanes (TTHMs) from Water?

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Understanding the range of water contaminants removed by reverse osmosis is important before investing in a system for your own home.

Reverse osmosis can be a very effective water purification method, but does it remove everything?

For one, what is the situation when it comes to trihalomethanes? Does reverse osmosis remove them? Let’s find out!

Key Takeaways

  • Reverse osmosis is very effective at removing trihalomethanes from water.
  • It removes them with an effectiveness of over 99%.

Does Reverse Osmosis Remove Trihalomethanes from Water?

So, does reverse osmosis remove trihalomethanes from water?

Yes, reverse osmosis is very effective at removing trihalomethanes from water. In fact, it’s one of the best solutions available on the consumer market for this purpose. If trihalomethanes are your primary concern, you should focus on reverse osmosis as your main choice.

How Effective Is Reverse Osmosis at Removing TTHMs?

Trihalomethanes, or TTHMs, are among the contaminants that get removed most effectively by reverse osmosis water purification. Reverse osmosis systems have an effectiveness rate of over 99% for this specific type of contaminant. This means that you will have less than 1% of their original concentration in your output RO water.

Under Sink Reverse Osmosis System

What Are Trihalomethanes (TTHMs)?

What are trihalomethanes in the first place though?

Chlorine is often used for disinfecting water in municipal facilities. It’s highly effective at eliminating bacteria and other pathogens, but also has some drawbacks. Most importantly, it reacts with certain elements in water, creating trihalomethanes. In low enough concentrations, these are not a problem for your health. However, high concentrations of trihalomethanes have been linked with issues like cancer and other health complications.

How Do TTHMs Enter Our Water Supplies?

Trihalomethanes usually make their way into your water through municipal treatment facilities. When water is purified using chlorine, some amounts of trihalomethanes might be created as disinfection byproducts. They don’t get filtered out before water is sent out into the town, and as a result they reach your water supply.

This is not an unknown factor. The people responsible for treating your household water are well aware of the presence of trihalomethanes in the filtered water. That’s why various legal regulations exist to limit the concentration of TTHMs in tap water. Those might not always be relevant to your area though. More on that below.

Health Risks

Consumption of trihalomethanes has been linked to various serious health conditions, including bladder and colon cancers. They could also lead to pregnancy complications.

That said, you shouldn’t worry by default because the concentration of trihalomethanes in water is really small in general. This could change under specific circumstances though, which is why it’s a good idea to have your water additionally filtered if you’re worried.

Regulations for TTHMs in Water

The concentration of trihalomethanes in public water supplies is regulated strictly. In general, you should not find them in higher amounts than 100 parts per billion in most areas. These rules are less relaxed in certain places though, for example areas with fewer than 10,000 inhabitants. If you live in a rural area, you might want to specifically verify your water quality.

If you’re concerned about the presence of trihalomethanes in your water supply and you live in a less populated area, you might want to talk to a local water treatment specialist to figure out what the situation is, before making any decisions on investing in a filtration system.

How to Test Your Water for Trihalomethanes

The best way to test your water for the presence of trihalomethanes and their exact concentration is to have it tested at a professional facility. These laboratories typically take a sample of your drinking water and provide you with a detailed analysis of its contents, including all contaminants detected and their amounts

It’s also possible to use a DIY test kit at home, but this is generally not recommended when talking about something more serious like trihalomethanes.

You could also check out your latest water quality report which is something every public water utility has to provide for free on an annual basis.

Other Ways to Remove Trihalomethanes from Water

Reverse osmosis is not the only way to get rid of trihalomethanes from your water. Other filtration methods can be used, too, although their effectiveness levels can vary.

Activated Carbon

Activated carbon is great at removing trihalomethanes. It also works well in combination with a reverse osmosis membrane. One of the main advantages of carbon filtration is that it’s cheap. Therefore, if you’re primarily concerned with removing trihalomethanes, you should invest in a carbon filter instead of a reverse osmosis system if you’re on a tight budget.

Water Softening

Even though that’s not the main intended purpose of water softeners, they too seem to remove trihalomethanes pretty effectively. Keep in mind that this might cause other complications though, and it could decrease the lifespan of your softening system. That’s why it’s recommended to use other methods that are specifically designed for water filtration.

salt-based water softener

UV Treatment

Finally, UV treatment can also be a very effective option when trying to remove TTHMs from water. Even though most people associate UV primarily with the removal of microorganisms and other biological contaminants, the process can also work very well against trihalomethanes.

The main concern you should have here is that the effectiveness of a UV purification system can be affected negatively by the presence of other contaminants in the water supply. This means that you might need to install additional filtration solutions alongside a UV filter.

If you have any thoughts about the question, does reverse osmosis remove TTHMs, please don’t hesitate to leave a comment below!

About the Author Gene Fitzgerald

Gene Fitzgerald is one of the founders of BOS and currently head of content creation. She has 8+ years of experience as a water treatment specialist under her belt making her our senior scientist. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
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