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Understanding UV Treatment of Water

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Ultraviolet light, also called UV light, is one of many water treatment options. UV disinfection works by altering microbial DNA and effectively killing waterborne microorganisms. Because UV rays don’t add anything to your drinking water during the treatment and disinfection process, it’s safe to drink UV-treated water.

However, UV disinfection is not the same as water filtration. These are two separate but complementary processes, which means you can have both a water filtration and a UV water treatment system.

Here’s what to know about ultraviolet disinfection, how it addresses specific water problems and why water filtration may also be necessary.

Understanding UV Disinfection

Ultraviolet light is a type of radiation with smaller wavelengths than visible light, which means it’s invisible to humans (but not to some other creatures, such as bumblebees). Direct exposure to UV rays — for example, from staying in the sun too long or using a tanning bed — can cause sunburn, premature skin aging and other issues; however, this isn’t a concern in UV water treatment. That’s because UV light passes through the water and never comes into contact with your skin. UV disinfection leaves behind no radiation and doesn’t even change the taste or smell of water.

UV water treatment protects against waterborne microorganisms that could make you sick, including E. coli. Although UV disinfection is generally effective against most microorganisms, some — including Cryptosporidium and Giardia — have thicker cell walls, which means low-power UV light systems can’t get through. As such, it’s important to ensure your UV system is designed to address your specific water problems.

UV Disinfection vs. Water Filtration

There’s no such thing as UV filtration. Think about it this way: In a UV disinfection system, UV light goes through water. In a water filtration system, water goes through a filter. The processes are different — which means the benefits are different, too. In many cases, both may be necessary to fully address drinking water problems.

So, how does UV water treatment work? It begins with a cylinder and a UV lamp. As water flows through the cylinder, the light attacks the microbes’ DNA and makes them unable to survive. Although this process may improve water quality, there are certain things it doesn’t catch — including sediment particles and some contaminants.* Low UV dosages also may not effectively inactivate some viruses, spores and cysts.

Do UV Water Treatment Systems Need Maintenance?

The output of the lamp, which runs on electricity and can generate heat, typically declines over time. Replacing it each year is a good idea. It’s also recommended to annually clean or replace the glass tube that houses the lamp and keeps it dry, which is called a quartz sleeve.

Where Does a UV Water Disinfection System Go?

Like many other home water treatment solutions, you can decide where to install your UV. You can disinfect all the water you use in your home by placing it at the point of entry, which is where the main water line enters a home. It doesn’t restrict water flow, so it won’t affect your water pressure. If you’re only concerned about treating the water you drink, however, you can install a smaller UV unit with pre-filters under the kitchen sink.

Better Treatment: UV Disinfection and Water Filtration

Ultraviolet water treatment is great for certain water problems, but it’s not a full drinking water solution. That’s because UV light doesn’t destroy everything you may want taken out of your water.

For instance, UV rays won’t remove contaminants such as arsenic or dangerous chemical compounds known as PFOA/PFAS. You also can’t count on UV water treatment to take care of sediment and particles of any size. Finally, UV disinfection doesn’t do anything to eliminate minerals such as calcium and magnesium, which cause hard water.

To handle these other water quality issues, you’ll need different systems:

  • Water filtration: There are two basic types of filtration systems: drinking water filtration and whole-home filtration. Both use actual filtration, not UV light, but they have separate processes and may create different benefits.
  • Water softening: Choose a water softener based on your water’s hardness, your water usage levels and other factors.

Can You Have Filtration and Disinfection?

Although water filtration and UV disinfection are two different things, they aren’t mutually exclusive. In fact, it’s often recommended to use both for a full water treatment solution.

Why? Here are just a few reasons:

  • UV movement: UV light can only travel in a straight line. That means particles, sediment and other contaminants or impurities can “block” the rays and lead to reduced efficiency.
  • Maintenance: Some substances can collect on a UV treatment system’s quartz sleeve, which may impact performance and can reduce the system’s overall lifespan.
  • Water quality: Remember, UV disinfection alone can’t handle every water problem. That’s why it’s smart to get the best of both worlds.

Can You Have Softening and Disinfection?

It’s not just filtration that coexists with UV disinfection. In fact, you can combine filtration, disinfection and softening for a complete water treatment solution. Because all three processes are different, none of these systems interrupts the others — and, in fact, they often benefit one another. For example, water softeners remove minerals such as calcium and magnesium, which can act as “shields” for microbes in the UV water treatment process.

Who Should Use UV Disinfection?

UV disinfection could be a promising option for just about anyone, but there are a few groups who find particular value in this solution:

Well Water Users

Well water users are often interested in UV disinfection — not just because it’s efficient, but because wells aren’t regulated or treated like municipal water supplies. Furthermore, wells can be contaminated in many ways; underground storage tanks can leak, for example, and water run-off can deposit animal waste and other harmful substances. Water quality can change quickly in wells, and UV can offer a layer of protection and help ensure safe conditions year-round.

City Water Users

UV treatment also has a role to play in homes that get their water from public water systems.

In the U.S., the Environmental Protection Agency (EPA) sets legal limits on more than 90 contaminants in public drinking water. In Canada, Guidelines for Canadian Drinking Water Quality are set by Health Canada’s Water and Air Quality Bureau in partnership with the provinces, territories and other federal departments.

Nonetheless, quality problems can occasionally pop up. Biological contamination may occur after a water main breaks, for instance. Additionally, issues may occur as the water supply travels from the municipality to the home, through supply lines or potentially fixtures within the home. That means UV disinfection isn’t just for well water users.

Anyone with Concerning Water Test Results

Routine and more advanced water tests can reveal potential problems in your water. If you get water test results that seem concerning, your first step should be discussing data with a local water expert. Depending on your water problems, they may recommend UV disinfection in addition to filtration and softening.

Customize Your Water Treatment Solution

When it comes to water treatment, you don’t have to settle for “good enough.” Instead, you need a combination of systems chosen based on your unique needs and water usage. With the right information, it’s possible to select filtration, UV disinfection and softening systems that work together seamlessly and create comprehensive water quality benefits.

To learn more about your water treatment needs, start by scheduling your free, in-home water test and consultation.

*Contaminants may not be present in your water.

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