Do UV Water Filters Work? (A Water Treatment Expert Explains)

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Keen to know whether a UV water treatment system will effectively eliminate microbiological contamination in your water? We’ve shared everything you need to know in this guide.

❔ Does the UV Water Disinfection Process Work?

The short answer is yes, UV water purification is a highly effective means of preventing microorganisms in your water from making you sick.

UV systems emit UV light from a light bulb that sits inside a glass sleeve. The UV rays pass through the glass sleeve and penetrate the water, scrambling the DNA of living organisms and preventing them from reproducing.

Does UV Disinfection Work to Prevent Dangerous Pathogens from Causing Harm?

Yes – the purpose of UV water purification is to alter the DNA of pathogens like bacteria, viruses, and protozoans, preventing them from reproducing or causing harm to anyone who drinks the water.

UV disrupts dna of microorganisms

Does UV Disinfection Work to Remove Pathogens?

No – a UV water filter doesn’t physically remove pathogens from water. Instead, the water supply is treated by ultraviolet light as it flows through the UV chamber.

The only way to physically remove microbiological contaminants is with a filter with small enough pores to trap these impurities, such as a reverse osmosis membrane. UV radiation is a much faster and more cost-effective means of treating pathogens in water.

Does UV Disinfection Work to Remove Dissolved Contaminants?

No – UV water purifiers don’t remove dissolved contaminants from water. A UV water filter is designed solely to treat living organisms. That means that any non-living organisms, like chemicals, heavy metals, and sediment, can’t be removed by a UV system.

If your water contains a lot of these dissolved contaminants, you’ll have to remove them with a form of pre-treatment to ensure that the ultraviolet light can effectively penetrate your water.

📤 How Does Ultraviolet Water Purification Work?

Now you know that UV systems do work, and you’re aware of the purpose they serve, you might be wondering how they work.

The UV treatment process works by sending water through a UV chamber. The UV lamp emits ultraviolet (or UV) light, which attacks the microorganisms’ genetic code, rearranging their DNA and preventing them from being able to reproduce or function.

UV light doesn’t actually kill or remove microorganisms from water, but it does render them incapable of causing harm in drinking water. Being unable to reproduce, a microorganism can’t replicate, so it can’t cause sickness and disease in the human body.

Related: What is UV transmittance & why is it important?

How uv purifiers work

🦠 What does Ultraviolet Water Purification Systems Remove?

The UV purification process is about 99.99% effective at deactivating harmful microorganisms in drinking water. Some of the contaminants that UV water purifiers can effectively target are bacteria, protozoans, cysts, some viruses, and fungi.

The list below highlights some of the different types of microorganisms that UV water treatment can target.

  • Cryptosporidium
  • Meningitis
  • Polio
  • E.coli
  • Flu
  • Cholera
  • Giardia
  • Typhoid Fever
  • Infectious Hepatitis
  • Dysentery
  • Salmonella
  • Coliform bacteria
Bacteria on Petri dish

⏱ How Quickly Does UV Light Kill Microorganisms in Drinking Water?

The UV water filtration process is incredibly quick. UV systems don’t require a water storage chamber to hold water while the ultraviolet rays penetrate the water.

Water flow shouldn’t be delayed at all by a UV water filter. Water flows through the UV chamber, and the UV light deactivates waterborne microbes in less than 10 seconds.

🔋 How to Know when a UV Light is No Longer Working

UV water filters only work for a certain length of time (usually 375 days). After this, the mercury in the light will have dissipated to the point that the lamp can no longer effectively disinfect water, and you’ll end up drinking untreated water.

So, how do you know when a UV light has reached the end of its lifespan? Sometimes it’s hard to tell. The bulb may still emit visible light, but that doesn’t mean the strength of UV filtration is adequate.

Most UV systems have an alarm or a light that alerts you when the bulb needs to be replaced. Otherwise, it’s worth marking a reminder in your calendar so you know exactly when you need to buy a new bulb.

Marking the calendar

Related Content: Easy Step-by-Step Guide to Replacing a UV Lamp

🆚 Does UV Water Treatment Work Better Than Chlorine Disinfection?

You might be caught between a UV system and chlorine water treatment to disinfect your well water.

Both methods produce very similar results, and you’ll get virtually the same level of protection from either.

However, UV is effective against two chlorine-resistant microorganisms: Cryptosporidium and Giardia. If you have a problem with these two particular pathogens in your water supply, UV will work effectively to remove them, while chemical disinfection won’t.

On the other hand, chemical disinfection can also oxidize iron and manganese, and is more effective than UV light in treating iron bacteria.

Ultimately, both systems work well to treat the majority of living organisms. The system that works best for you is the one that best suits your budget, maintenance preferences, and contaminant removal requirements.

🤔 Do UV Systems Work Best Before or After a Water Filter?

The UV purification process is most effective when the UV system is installed after, or downstream of, other water treatment systems, like whole house filtration systems and water softeners.

Why is this? Because UV is less effective when water contains a lot of contaminants. So, if you remove these contaminants with a water treatment system before they even reach the UV system, the UV light will more thoroughly penetrate the water, better protecting you against microorganisms.

Another benefit of installing a UV water filtration unit downstream of other filters is that UV can remove any potential microbiological contamination from the filters themselves. Filters are moist environments designed to trap dirt and impurities, and bacteria buildup in the media is common. If you install a UV light before a filtration system, the water could become contaminated with pathogens after the UV treatment.

Whole house water treatment system with UV filter diagram

📝 Why Use a UV Water Purifier?

Some of the biggest benefits of using UV water filters are:

  • You’re well-protected against a whole host of dangerous pathogens, like bacteria, viruses, and protozoans.
  • UV filters even treat chlorine-resistant microorganisms with thick cell walls, like Cryptosporidium and Giardia.
  • A UV water purifier works efficiently, offering an environmentally friendly disinfection method that uses no chemicals – just a UV lamp.
  • UV water systems are minimal maintenance. The UV bulb needs changing about once a year to continue to emit UV-C light that’s strong enough to target pathogens. The sleeve needs replacing about once every three years.
  • UV filtration can be combined with other filtration methods to protect you against a whole host of water impurities in contaminated water, from harmful microorganisms to heavy metals, dangerous chemicals, and more.

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❗️ Takeaway

Does a UV water filter work? Yes – but only to deactivate harmful microorganisms in water.

Don’t expect a UV filter to remove harmful chemicals or other contaminants, and don’t expect ultraviolet technology to physically remove bacteria and other organisms from water. UV doesn’t even kill bacteria – it just alters the microorganism’s cellular function.

In short, using UV to treat water is a fantastic environmentally-friendly alternative to using chemical disinfectants. Just make sure you know exactly how the ultra violet method of disinfecting water works, so that you can decide for certain whether it’s the right method for you.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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