RO vs UV: Which Purifier is Best for Your Health?

RO vs UV

Water purifier manufacturers use different purification technologies. But RO and UV are the two purifiers that are widely used. If you are also confused between RO vs UV water purifiers, this guide will help you select the best according to your needs.

Pollution is a major problem in India. Water bodies are highly polluted, especially in urban areas, and India’s huge population adds more pressure. Thus, the purity of waters is a matter of concern, whether it is groundwater or municipal supplies.

Water purifiers are necessary to get clean water as water is a fundamental prerequisite of good health. They are necessary for every household, from removing dirt to removing microorganisms like viruses and bacteria.

There are numerous water purifiers available in the market using different water purification technologies. Manufacturers are competing to lay up the market niche as water purifiers have become an indispensable part of every household. 

Amongst water purification technologies, Reverse Osmosis (RO) and UV (Ultraviolet) technologies are widely recommended. So, let us understand these two technologies well. Consumers also have an added advantage of getting them during Festive offers and discounts offered by Water purification product Companies regularly.

What is RO?

RO is a form of water purification where osmosis makes the water molecules pass through a semipermeable membrane with their pores having a diameter of the order of microns. You can eliminate over 95% of the total dissolved solids present in the water supply under high pressure. 

This filtration method converts hard water to soft water by removing the dissolved salts, large particles, impurities and microbes from the water. It results in flux such that only water molecules move to the other side of the semipermeable membrane, and the dissolved salts and other impurities stay behind. 

Thus, RO purified water remains free from harmful bacteria and dissolved contaminants. It ensures that the water filtered out from the RO unit is as clean as it can be.

How does it work?

RO water filtration is a straightforward process. It is done by water pressure forcing tap water through a semipermeable membrane removing contaminants from water. You can remove all of the dissolved inorganic solids from the solution in this process. This process is different from standard filtration, where impurities are collected within the filtration media. 

In the RO process, water is pushed through a series of filters, and ultimately the clean water is led to the holding tank, with the contaminants flushing down the drain. If the Total Dissolved Solids (TDS) levels are, say, 800 ppm, post RO treatment, it will be in the range of 80 ppm.

Likewise, if the TDS is saying 100, then after the RO process, it will drop to 10. TDS levels of over 500 ppm require a RO system because using an RO purifier for a low TDS can strip away minerals like calcium and magnesium.

What is UV?

UV purification is an excellent option for treating water with a low TDS to remove microorganisms like bacteria and viruses without removing essential minerals in the drinking water. Water treated by the authorities, the soft water may be contaminated during distribution, UV treatment is very efficient in purifying the treated water at the point of use. 

In this filtration system, harmful bacteria of the water is killed with Ultraviolet rays. It will completely disinfecting the water from pathogens. It is good for health as it kills all the harmful microbes present in the water keeping the taste intact. These purifiers come in a wide variety, and the UV system’s size depends on the rate of water flow.

How does it work?

A UV water purifier uses germicidal ultraviolet light to treat microbiologically unsafe water. It scrambles the DNA of the organisms in the water, so they can no longer reproduce and make a human sick. If one drinks bacteria-infested water, the organisms enter the digestive tract and replicate.

Ultraviolet radiation damages the DNA of bacteria, viruses and fungi, making them unable to replicate. The Purifier exposes the microbes to a germicidal ultraviolet wavelength at 254-nm wavelength. UV dosage measures the energy (in MJ/cm²) of a UV water purifier.

The dosage provided is proportional to the energy delivered to treat contaminated water. At a point, this energy inactivates most of the microorganisms present in the water.

UV systems are point-of-entry systems, i.e., they are installed before the water enters the home, purifying the water throughout the house. Most often, average household pressure is enough for operating a UV system.

Pros of using RO

An RO water purifier efficiently filters microbes and heavy metals as the Total Dissolved Solids include the organic and inorganic matter dissolved in the water supply, including microbial contaminants and heavy metals, thus protecting microbial contamination from water-borne diseases. 

In the long run, the accumulation of heavy metals results in toxicity. You will get sweet and soft water from Hard water with TDS up to 2000 ppm using an RO purifier. You will get pure and hygenic water from your RO after the removal of the microorganisms. 

Additionally, the RO water purifier filters both suspended and visible impurities and effectively purifies muddy water. While selecting between RO vs UV you should consider these pros of RO.

Cons of using RO

RO water purifiers consume huge amounts of water in every purification process, giving rise to high water wastage through the reject stream. You will waste around 80% of water in a household RO system. 

Although You can use this wasted water for cleaning floors, vehicles, or gardening, you can also mitigate this problem by using a TDS modulator in the purification unit. Also, using a RO water purifier for low TDS input water (less than 200 ppm) can be harmful to health in the long run, as the water is devoid of essential minerals and salts. Another problem is that to increase the water pressure for the water to pass through the membrane, RO requires electricity.

Also, RO cannot differentiate between good minerals and bad effluents while removing over 95% of the total dissolved solids. So, often it ends up in losing the minerals that one expects to consume through the water. Most people choose UV purifier because of this advantage while looking RO vs UV.

Studies show that RO purifiers, other than removing impurities, also remove essential minerals for the body like calcium, potassium, magnesium and sodium from the water. A system with RO and Mineral fortification technology retains the good minerals.

Pros of using UV

UV water filters can work with normal water pressure. It is efficient in purifying the water by removing bacteria. The taste of water does not change. UV purification is one of the most eco-friendly purification techniques.

Without adding any chemicals to water, it gives 99% of microbial elimination by deactivating the nucleic core and killing reproductive capacity. It does not cause any wastage of water. If your TDS is less than 500 the simply choose UV without comparing RO vs UV technologies.

The treatment process does not requires draining of water. UV disinfection deactivates microbes like Cryptosporidium, Giardia, Mycobacterium tuberculosis, Dysentery bacilli, Fungi, Salmonella, Hepatitis B, Cholera. In the treated water, UV wavelengths do not leave by-products like chemical disinfectants. It does not alter the water chemically in any form. It is easy to maintain. 

During disasters, UV systems provide safe drinking water. When compared with RO, RO purifier does not eliminate microbes from the water supply, and this is where UV water technology comes into play. 

Cons of using UV

The TDS value of UV purified water remains constant. UV may not be very effective if your water’s turbidity is high as the radiation will not uniformly spread across all the microbes. 

Although UV water purifiers kill bacteria and viruses, they do not remove dissolved impurities such as rust, fluoride, arsenic etc. They do not convert hard water to soft water. You cannot remove the microorganisms after killing them from water in UV treatment process. 

Also, you cannot disinfect the highly sedimented and muddy water with UV purification. They do not remove bad tastes and foul smells from water. Since UV only deactivates the living organisms, the system needs a prefiltration to remove unwanted particles. 

Another disadvantage is it heats the water. Even when one is not running water, the UV lamp heats the water. The other major disadvantage is it doesn’t work without a power supply. The system requires electricity to run.


We hope we covered most of the questions for choosing between RO vs UV purification technology as there are many reasons to use a water purifier at your home. Once you decide the purification technology you need, choose the water purifier for your home to get safe drinking water.

As a rule of thumb, checking the TDS of water with a simple TDS meter is the first step. If the TDS is above 500 ppm, you can choose an RO water purifier. And if it is lower than 500 ppm, then a UV water purifier will be more effective. 

A combination of RO and UV technologies is ideal and recommended for the ultimate health of everyone. Although It is not feasible for remote areas where electricity is a must for the system to function. It is advisable to go for a large water storage capacity with RO + UV purifier to cover the all-around needs.


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