Which UV Light Is Used in a Water Purifier?
Written by: Gene Fitzgerald // Last Updated: Nov 22, 2022
This page may contain affiliate links. If you buy a product or service through such a link we earn a commission at no extra cost to you. Learn more.
UV water purifiers utilize ultraviolet radiation to effectively sanitize water.
Sounds pretty cool, but don’t UV rays come naturally from the sun? If so, why should you invest in and install a UV purifier instead of just exposing your water source naturally to sunshine? Well, it’s not that easy.
Here we will break down what type of UV light is used in a UV water purifier and why it can do what the sun cannot.
Contents
show
Key Takeaways
- UV-C is the strongest UV light and is used in UV water purifiers. It is lethal to pathogens in water.
What Is UV light?
There are three kinds of UV wavelengths: UV-A, UV-B, and UV-C. 95% of the Sun’s rays that reach the Earth are UV-A, and the remaining 5% are UV-B. The most powerful of the three are UV-C rays, which cannot reach the Earth’s surface as they are blocked by the ozone layer. Therefore, the only way it can be used is from artificial sources, like UV lamps.
UV-C is the only one that is germicidal, meaning it has the power to deactivate the DNA of pathogens, and stop them from multiplying and spreading disease.
Which UV Light Is Used in a Water Purifier?
In a water purifier, a UV-C light of 254nm wavelength is used. It’s the most lethal dose to pathogens in water and is often referred to as germicidal ultraviolet. Short exposure to this wavelength will scramble the DNA of the microorganism, killing it as it attempts to replicate.
How Does a UV Water Purifier Work?
A UV water purifier is usually installed as the last step to completely sanitize water. After moving through the relevant pre-filters, water will pass through this tube-shaped device, which will expose the water to UV-C rays emitted from a long, UV light bulb. The bulb sits within a quartz sleeve which keeps it separated from the water while still allowing UV rays to penetrate it.
The flow rate of the water will determine which kind of system you need. A standard lamp will work for most households with a low to medium flow rate, but in commercial settings, a high-output UV lamp may be used.
System Components
The main components of any UV water purifier are;
- A UV light bulb that emits UV light in all directions.
- A quartz glass sleeve that encases and protects the UV light bulb.
- The main chamber, which surrounds the quartz glass sleeve, where water flows to be exposed to the UV light.
- Connecting seals at either end of the main chamber which allow the unit to be hooked up to the water supply.
- A control unit that manages the light bulb, and often contains additional features such as sensors and alarms to indicate light bulb change times.
- O-rings to help seal water and prevent leaks.
What Does a UV Purifier Remove from Water?
While a UV purifier is 99.9999% effective when it comes to destroying microorganisms, it is important to note that it cannot remove anything from the water. The purifier will effectively treat
- Bacteria (e.g. dysentery bacilli, salmonella, E. coli)
- Cysts (e.g. cryptosporidium, giardia)
- Viruses (e.g. hepatitis, rotavirus, poliovirus)
- Fungi
- Algae
But it will not remove sediment, heavy metals, other dissolved particles, odor, or even the microorganisms after they have been killed. In other words, it will not change the chemistry or aesthetics of the water.
Does UV Light Work in All Water Conditions? When Do I Need a Pre-Filter?
The short answer is no. A UV water purifier is top-of-the-line in water sanitization, but it needs certain conditions to do its job effectively. If your water source contains particles or sediment, however tiny, there is a chance that microorganisms can hide behind it and avoid exposure to the globe’s UV rays. This is called ‘shadowing’.
In most cases, a pre-filtration system needs to be installed to remove things like sediment and iron, or you may even need a water softener before the purifier can work. The best way to determine what you need is to have your water tested to see if it meets the following criteria:
- Hardness < 7 grains per gallon (gpg)
- Iron < 0.3 ppm
- Manganese < 0.05 ppm
- Turbidity < 1 NTU
- Tannins < 0.1 ppm
If it does not, you will need to have the necessary pre-treatment systems installed.
UV Water Filter Maintenance
Along with regularly checking the unit for leaks and damage, you will need to perform scheduled maintenance on the purifier at least yearly. The great thing is that this is relatively easy to do yourself, especially compared to other disinfection methods.
The UV light bulb needs to be changed once a year, and the quartz glass sleeve cleaned. If you notice permanent fogging on the sleeve, this needs to be replaced too, usually every 2 years. O-rings should be kept on hand to quickly address any leaks before they become a more serious problem.
Further Reading:
Are UV Purifiers Safe and Effective?
If used correctly and properly maintained, UV water purifiers are 99.9999% effective and very safe. Regular maintenance and installing proper pre-filtration are vital for this. If you have hard water, it may need to be softened as this can cause the quartz glass sleeve to fog up faster and need more frequent replacement.
Pros and Cons of UV Water Disinfection
The Pros:
- Chemical free. UV water purification does not expose the water to any chemicals.
- A 99.9999% disinfection rate makes it one of the most effective water sanitization methods on the market.
- Simple design that does not require advanced technical skills to understand or maintain.
- Very low-level maintenance can be done yourself at home.
- Household units for low to medium water flows use minimal power, making them very cost-effective.
The Cons:
- Does not remove anything from the water supply.
- Often requires additional pre-filtration for effective use.
- Requires power to work – will not operate when the power supply is cut.
If you have any questions about which UV light is used in a water purifier please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
Information provided on BOS is for educational purposes only. The products and services we review may not be right for your individual circumstances.
We adhere to strict editorial guidelines. Rest assured, the opinions expressed have not been provided, reviewed, or otherwise endorsed by our partners – they are unbiased, independent, and the author’s alone. Our licensed experts fact-check all content for accuracy. It is accurate as of the date posted and to the best of our knowledge.