Is RO UV Water Purification Required? When?

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.

RO UV water purification combines reverse osmosis filtration with ultraviolet water disinfection.

It’s a super effective combo, but it’s not always necessary. So how do you know when you need it?

This article will explain when you need an RO UV system and its pros and cons among other things.

Key Takeaways

  • RO UV purification is required when water is heavily contaminated with TDS and microorganisms.
  • Testing your water for contaminants is the only way to be sure you require RO UV water purification.

Is RO UV Water Purification Required? When?

Reverse osmosis technology is used to purify water that’s heavily contaminated and unfit for drinking. It’s often recommended for homes with serious water issues like heavy metal contamination and high TDS levels (total dissolved solids). Reverse osmosis also comes in handy when dealing with contaminants that most filters can’t handle, like arsenic or fluoride.

On the other hand, UV water purifiers are used to tackle microbial contamination. They’re renowned for being one of the safest and easiest ways to clear water of harmful microorganisms. So they’re your best bet for killing pathogens like bacteria and viruses.

Now, back to reverse osmosis: You wouldn’t usually need an RO system unless your water supply quality is pretty bad and you are facing several different types of contaminants.

But while reverse osmosis eliminates up to 99% of all impurities in water, you can’t trust it to remove all microorganisms – which is necessary because even small amounts of certain waterborne bacteria for example can already make you sick. The solution is an RO UV system that combines RO and UV purification to achieve the best filtration outcome.

Under Sink Reverse Osmosis System

But remember, not everyone needs to get an RO UV system. The only way to know if you need one is to get your water tested. Tests show you the current state of your water supply and give you insight into what treatment method would be best. So if your water test results come back with heavy metals, nitrates, arsenic, chemicals, etc. and microbial contamination, you’ll benefit from an RO UV water system for sure.

By the way, RO UV systems come as point-of-use and whole house water filters.

Is UV Necessary with RO?

UV is sometimes necessary with RO, but we can’t say it’s always necessary. Remember, the right water treatment method depends on the water’s quality. So, UV is only necessary with reverse osmosis when the water has serious microbial contamination.

A water test will reveal if you need to combine a UV system with your RO. A large part of why RO + UV systems work so well against microorganisms is that the RO system first removes the solids that said microorganisms could hide behind, ensuring that the UV light hits and kills all of them.

Is RO UV Needed on Municipal Water?

Ordinarily, municipal water should be safe enough without UV disinfection. Strict regulations ensure that the water supplied to homes meets the requirements for microbe population. Chlorination and other treatment methods are used to achieve that.

However, you can’t always guarantee the safety of municipal water, and getting an RO UV system could serve as extra protection. Your municipal water may need additional purification when:

  • An issue with the water supply line makes the water temporarily unsafe.
  • There’s a source of contamination along the service line that transports water to your home.
  • There’s heavy metal contamination from the pipes and systems used.
  • There’s a boil water advisory.
  • There’s an increase in the microbe population when water is stored in storage tanks.

An RO UV system could protect your municipal water in any of the above situations, making it a worthy investment.

What Is an RO UV Water Purifier and How Does It Work?

An RO UV purifier is a system that combines reverse osmosis water purification with UV water disinfection. The UV purifier (UV lamp) comes after the RO system, working as a post-filtration stage.

RO tackles the issue of dissolved and floating organic + inorganic contaminants, while UV purification deactivates and kills microorganisms like bacteria and viruses.

Since RO + UV is typically required when the water has high TDS levels and microbial contamination, the filters often have several stages of purification, usually depending on the brand.

The various pre-filters and the RO membrane are placed before the UV purifier, ensuring the water is particle free, so the UV light works effectively.

A typical RO UV filter will have the following stages:

  • Pre-filtration stage: This stage features one or more filters, depending on the brand and what contaminants they aim to remove. These filters target large solids and chemicals like chlorine. A sediment filter often comes first, followed by a carbon filter to remove oil. Sometimes, there is more than one carbon filter.
  • RO membrane: This stage is practically the heart of any reverse osmosis system, where most contaminants like heavy metals, salts, pesticides, and other dissolved solids are removed. In this stage, water is pushed through the semipermeable RO membrane under high pressure to reject impurities, while clean water diffuses through the membrane.
  • Post-filter stage: This stage gives the water its final polishing. First we have the UV lamp. It’s placed in a tube of clear quartz. As water flows through this tube, the UV light attacks the DNA of microorganisms, instantly deactivating or killing them, rendering them harmless. Next comes a carbon post-filter removing residual taste/odor.

What Contaminants Are Being Removed?

RO UV filters can remove a broad spectrum of water contaminants:

  • VOCs
  • Minerals and salts
  • Pesticides/herbicides
  • Heavy metals
  • Chlorine/chloramine
  • Sediments
  • Nitrates/nitrates
  • Bacteria
  • Viruses
  • Cysts and some other microorganisms
  • Other organic and inorganic contaminants

bacteria in water

The Pros & Cons of Reverse Osmosis + Ultraviolet Water Treatment

Like every other technology, RO UV water treatment has both benefits and disadvantages. Here are some that are worth noting.

The Advantages

  1. RO UV systems remove a broad spectrum of water pollutants and eliminate any harmful microorganisms. Talk about double protection!
  2. RO UV systems are relatively low maintenance as stand-alone systems, so you won’t have to do much maintenance even when they’re combined.
  3. RO + UV reduces the risk of waterborne diseases.
  4. RO UV systems eliminate water hardness.
  5. They eliminate foul odors and improve the taste of water.

The Disadvantages

  1. Many standalone RO systems produce a large amount of wastewater while producing only a small amount of clean water. Unfortunately, this doesn’t change when combined with UV.
  2. RO water loses most of its mineral content, giving it a slightly flat taste. You should consider remineralization (also for health reasons).

If you have any thoughts about the question, is RO UV required, please don’t hesitate to leave a comment below!

About the Author Alexandra Uta

Alex is a content writer with an affinity for research and a methodical attention to detail. Since 2020, she has fully immersed herself into the home water treatment industry only to become an expert herself. Alex has been using water filters and similar products for years which has gained her lots of hands-on experience.
Learn more about .


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.

Leave a Comment: