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RO vs UV: 9 Differences between RO and UV Water Purifiers

Due to rising pollution levels and poor water quality, a good water purifier has become a necessity in every household. Although there are numerous water purifier models in the market, the quality and durability matter the most!

The two most popular purification technologies are reverse osmosis (RO) and ultraviolet (UV). Understanding the principle and workings behind both is the best way to determine which one is superior.

Are you thinking about purchasing the best water purifier for home use? We got you covered!

Due to the lack of time in today’s society and the overwhelming number of options, we have written this article to assist you in making an informed decision.

This article will walk you through the working process of the two purifiers and compare them based on nine characteristics!


RO Water Filters

RO Water Purifier

RO is a method of removing contaminants from drinking water that employs a semipermeable membrane. The semipermeable membrane functions as a sieve, removing large particles such as sodium chloride, soil, sand, and so on.

In contrast to osmosis, reverse osmosis necessitates the application of external pressure. Why? Because osmosis involves water flow from a higher concentration solution to a lower concentration solution, which is natural, no additional pressure is required.

Reverse osmosis produces the exact opposite effect. Pressure is applied to reverse the osmotic pressure, allowing water to pass from a higher concentration (Contaminated Water) to a lower concentration (Pure Water).


Working of RO Filters

RO systems can have three, four, or five filter stages, depending on the model. Generally, the entire process can be divided into four phases. Every stage utilizes a specific membrane/filter for the purification of impurities.


1. Sedimentation Tank

The sediment filter is functionally similar to a sieve. It separates large particles and a few dissolved solids. Particles like soil, sand, grit etc., are separated via this membrane.

2. Pre Carbon Filter

This stage disinfects chlorine and other molecules that alter the taste and odour of water. These filters are made of carbon, which can absorb a wide range of gases and molecules.

3. RO Membrane

The RO membrane is the most critical component in removing significant health risks. Dissolved solids from water, including heavy metals, are removed due to external pressure. The waste or contaminants left behind in the membrane is released through a drain pipe.

4. Post Carbon Filter

The water is filtered through the post-carbon filter before entering the storage tank. This stage helps to improve the water quality by removing odour and taste. Hence it is also referred to as a polish filter.

The filter ensures that all remaining contaminants are removed from the product as it passes through the membrane. It ensures that the product is entirely pure and fit for human consumption.


UV Water Purifiers

uv water purifier

The Ultra Violet System (UV) is a water purification method that uses ultraviolet light to disinfect the water.

Sunlight contains ultraviolet (UV) radiation, UVA, and UVB rays can cause skin cancer and sun damage. However, another not so popular is UVC rays. It is less prevalent on earth; however, it is very effective as a disinfectant.

UV rays penetrate the microorganism’s cell wall and damage its DNA. Because the genetic code has been destroyed, the organisms are unable to replicate, making them non-infectious.


Working of UV Purifiers

UV filters have a relatively simple build. It consists of a UV lamp that is enclosed in glass quartz. UV light can penetrate the glass and disinfect the water. The glass covering prevents the UV bulb from coming into indirect contact with water.

This setup is enclosed in a stainless steel chamber. The wavelength of light that works best for disinfection is 245nm.


RO Filters vs UV Purifiers

Now that we know the difference between the principle and working of RO Filters and UV Purifiers let us dive into nine differences between their characteristics.

1. Total Dissolved Solids:

TDS is total dissolved solids, organic as well as inorganic. A high number of TDS in water can make the water hard and unpleasant to taste and smell.

Additionally, if the water is contaminated with heavy metals like lead, copper, arsenic, silver, etc., it can cause severe health issues. Multiple studies have also indicated a direct correlation between dental fluorosis and fluorinated water.

UV radiation CANNOT reduce the level of TDS in water, whereas RO filters are designed with multiple filters to eradicate solids from the water.

If the TDS of your water is 300 ppm and above, you must invest in an RO filter.


2. Water Source:

Since we discussed TDS, we should be aware of the source of the water we are drinking. If the water in your house comes from rivers, lakes, ponds, or the municipality, it most likely has a low TDS. If the TDS of the water is low, an RO filter is not required.

When your water is drawn from groundwater or adjacent to industries, it is more likely that the TDS level will be high. In this case, you should invest in an RO water filter.


3. Microbial Elimination:

When it comes to microorganisms, RO and UV water purifiers work differently. It is a UVC filter that kills microbes-UVC Rays at work! On the other hand, RO filters are intended to filter dead microorganisms; they cannot kill microorganisms.

It results in biofouling, which is a significant disadvantage of the RO filter. Biofilms are produced when microorganisms attach and colonize on the membrane surface. It is very concerning because the accumulation of biomass on the filter will reduce its efficiency over time because of clogging.

Thus, UV filters are a better option if the TDS is low and the only goal is to eliminate microbes.


4. Maintenance:

Regular cleaning and maintenance of both water purifiers are necessary to ensure a clean, purified water supply. RO purifiers are very costly to maintain as their filters are expensive and need to be cleaned every six months. Because of biofouling, RO membranes need to be replaced every two years to ensure the water is adequately purified and free of contaminants.

There is no guarantee that the UV light will provide adequate disinfection after one year; hence it needs to be changed annually. The glass sleeves are easy to maintain, and they need to be cleaned once in six months.

Hence, maintenance and replacement of parts in a UV purifier are pocket-friendly compared to RO purifiers.


5. Taste of Water:

Water does have a taste! According to WHO, drinking water with a high TDS level has an adverse effect on its taste. Water can taste bitter or salty depending on the solid dissolved in it.

Water is sweetened and enhanced with RO purification. Additionally, it is the only purification method that improves the taste of purified water. Who wouldn’t like tasty water?

According to a research article published in Science Direct, Organic materials, high disinfectant content, and poor water treatment can cause water to turn a different colour. 

RO purifiers can tackle all these issues and improve the overall aesthetics of water, including the smell and colour.


6. Wastage of Water:

You may find this surprising, but RO purifiers waste a lot of water! An average RO water purifier wastes approximately 50% to 80% of its water supply, which means that for every half litre of filtered water, about two and a half litres of water is wasted.

UV water purifiers do not waste any water; hence it is superior in this aspect. However, the wastewater generated can be recycled and utilized for household tasks like cleaning and washing.


7. Storage Tank:

In contrast to UV purifiers, RO purifiers always include a storage unit that can hold 5-10 litres of water. Typically, UV purifiers do not have a tank. As a result, you must manually fill up and consume water each time.

As an RO filter doesn’t require frequent use, you can save electricity.


8. Time:

Since the number of steps involved in purifying water using an RO filter is more in number, the time required will also be more. If you are searching for a cleaner that can give you pure water instantly, you may want to select UV purifiers.


9. Cost:

RO purifiers are expensive! Additionally, as mentioned above, the RO filter is expensive, and replacing them can also be costly.

If you are looking for a budget-friendly option, you should choose a UV purifier.


Also Read:

Water Purifier Under 15000

Water Purifier Under 10000

Electric VS Non-Electric Water Purifiers



So, which one is better? Well, both RO and UV purifiers are excellent choices to decontaminate water; however, both work on their unique principle and eliminate different contaminants from water.

UV purifiers are an excellent choice for those on a tight budget. It can be an excellent investment if your water supply has low TDS and is contaminated only with microbes. In such cases, using a RO purifier may be detrimental because it reduces the number of dissolved ions in the water.

However, if your water contains a high TDS level, a RO filter is the best option.

Let us know if you found this article helpful. Do let us know in the comments which purifier you use and why!

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