Is UV Required With Reverse Osmosis?

We partake in many different activities to maintain our health, including exercising and eating healthy foods. However, most of us fail to realize that clean water plays a crucial role in good health.

Even distribution pipelines are not in the best of conditions around the globe, and water bodies such as lakes, rivers, and oceans are polluted to an alarming level.

The two most popular ways to get safe water are reverse osmosis (RO) and ultraviolet (UV) technology.

Most people get confused about whether they should use UV with reverse osmosis or not. So if your water has high microbial contaminants, you should use UV purification before reverse osmosis as reverse osmosis can’t remove micro-level solvents like viruses. Only UV rays can kill microorganisms in your home water.

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Is UV Required With Reverse Osmosis?

UV Required With Reverse Osmosis

It is very important to know the quality of the water available before deciding on a water purification system.

The quality of water is measured by its TDS level. TDS is an acronym for its full name Total Dissolved Solids. Putting up in simpler words, it refers to the ratio of contaminants and pollutants in water.

The World Health Organization recommends that water whose TDS level is less than 300 mg/L is safe to consume.

Now coming to the answer to your question;

  • If TDS in water is within permissible levels and does not contain many impurities is affected by microbes, a UV purifier alone will work.
  • If water is contaminated with solids like heavy metals, sediments, chemicals, and only an RO water purifier will do the job for all other situations.
  • If the water is loaded with solid contaminants and infected by bacteria, viruses, and algae, it would be important to use UV and the RO system.

Types of UV

Unlike visible light, ultraviolet light is a form of electromagnetic radiation with a wavelength between 10 nanometers and 400 nanometers.

A significant amount of UV radiation is emitted from the Sun during the day and makes up about 10% of its total output.

Here are some of its types that we need to know to understand the mechanism of UV Filtration.

  • UVA: It ranges from 315 nm to 400 nm in wavelength. Around 95 percent of the UV radiation hitting the surface of the Earth is UVA, which has relatively long wavelengths. The tan that appears immediately within days is due to this type of UV radiation penetrating the deeper layers of the skin.
  • UVB: It ranges from 280 nm to 315nm in wavelength. The skin does not absorb these wavelengths. In the short term, it leads to premature skin aging and skin cancer development by accelerating the aging process.
  • UVC: It ranges from 100 nm to 280nm in wavelength. Ultraviolet C radiation has the greatest potential for damage. The planet’s surface is not affected since it is completely filtered by the atmosphere.

How UV Filtration Works

A UV water purifier makes living organisms, such as bacteria, viruses, algae, and other harmful microbes, prone to ultraviolet wavelength having the ability to kill them.

UV water purifier works by attacking the microbes with high-energy UV radiations of the wavelength of 254 nm. Pathogenic microorganisms cannot reproduce when their DNA is disrupted by UV radiation. Thus, drinking water does not spread diseases when bacteria cannot reproduce.

UV radiation imparts energy to purify contaminated water to the degree of its intensity. When the energy level reaches a certain point, most microbes in water are inactivated.

Water can be disinfected effectively with Mercury low-pressure lamps that impart 254 nm UV light on contaminated water. Microorganisms are inactivated due to UV light adsorption by DNA and proteins in the cells.

New developments in UV lamp technology have allowed for special lamps that emit both 185 nm and 254 nm wavelengths of UV light.

When organic compounds are exposed to this combination of wavelengths, they are photo-oxidized. A (Total Organic Carbon) TOC level of 5 parts per billion (ppb) can be achieved in top-quality water using these special lamps.

PROS of Ultraviolet Purifiers

  • UV purifiers are affordable.
  • The maintenance costs are also lower.
  • A chemical-free filter prevents water from losing its taste as well.
  • Clean water is available instantly.

UV Water Purifier Side Effects

Germs and other microorganisms cannot be physically removed from water by ultraviolet purifiers. A powerful UV light, however, can kill them. However, the dead bodies in the water remain after this light kills the microorganisms.

Therefore, you might require to use both UV and UF purifiers together to get fully purified water.

  • A UV light can only eradicate microorganisms found in water. Solid contaminants such as heavy metals, salt, chlorine, petroleum products, or pharmaceuticals can not be removed using UV technology. UV should be used in conjunction with other filtration methods to ensure water purification by removing solid contaminants.
  • Water must be clear for UV light to work. An ultraviolet (UV) prefilter should be used if the water contains solid visible particles because UV rays cannot penetrate microorganisms due to their path being blocked by other particles.
  • Electricity is required to operate UV water systems. A UV may not be the best choice in rural areas, in emergencies, and for survival purposes without electricity.

What is RO UV?

What is RO UV?

The RO UV filtration combines both Reverse Osmosis and UV filtration system. Water is purified and filtered using this system, which effectively purifies 100% of the water.

Not only does it remove solid contaminants that are dissolved minerals and suspended particles, but it also removes biological contaminants that are microbes like bacteria, viruses, and algae with a RO UV disinfection system.

Conclusively, the water purified through an RO UV system is free from microbes and has a lower TDS level.

Do You Need a UV Filter If You Have Reverse Osmosis?

The answer to this question depends on the quality of water available.

For a quick answer, a UV filter is required with Reverse Osmosis only if the water supply has a high TDS level and high levels of bacteria, viruses, and other microbes.

Ultraviolet systems and prefilters make water cleaner by removing sediment and chemicals. Then bacteria in that water is killed.

Bypassing water through a Reverse Osmosis system, over 95% of the mineral content is removed, while chemicals like chlorine are also removed due to the prefilters.

Using a UV filter with Reverse Osmosis is better than using any of the two alone.

RO UV or RO UF? Which one is best?

RO UV and RO UF are combinations of Reverse Osmosis with Ultraviolet Radiation System and Ultra Filtration system, respectively.


A RO system filters all living organisms out of the water by physically removing the germs and viruses. Furthermore, the filter holes in RO membranes can remove even salts dissolved in water.

A UV water purifier does not physically remove germs or other living organisms but kills them with its powerful UV light. However, the bodies of the dead germs remain in the water after the UV lamp kills the germs.

The UV light must travel through water for the purifier to work properly. Therefore, the water needs to be as clear as possible not to obstruct the UV rays.

Combining these two can kill microbes, remove their dead bodies and remove solid contaminants providing purified water.


An RO and a UF system are both based on membranes. Their differences are primarily in the size of their filter holes. It is possible to filter out salt molecules from water using an RO membrane because the filtering holes are so small.

UF membranes have larger holes, making them unable to filtrate salt molecules. But even the smallest living organism, viruses, can fit through the UF membrane filtering holes.

Alum or iron salts can coagulate dissolved substances before they can be removed by ultrafiltration.

UF water purifiers are efficient because they work without electricity. The UF membrane is incredibly small and can even filter out all dust particles, leaving the water safe to drink.

UF water purifiers only have one major drawback: in the event of harmful dissolved salts in water, the filters cannot remove them.

When combined with an RO water purifier, all the harmful salts and microbes are removed. That is why the RO and UF water purifier is considered one of the most efficient systems.

In our opinion, RO UV is better in purifying water because they remove all dissolved, suspended contaminants and microbes.

Final Words

Conclusively, using a UV with RO system increases efficiency and improves filtered water quality.

RO-UV systems are the most efficient way to remove impurities from water because the RO removes dissolved and suspended impurities, while the UV system eliminates microorganisms.

In addition to removing bacteria, viruses, algae, heavy metals, minerals, and other contaminants from water, an RO UV system will also achieve maximum water clarity.

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