RO vs UV vs UF vs MF- What are the Differences? Complete Guide

November 16, 2021 / RefrigeratorPro Team

If you are planning to purchase water purifier, then you would have come across terms such as RO, UV, UV, MF. In this post we will explain all these terms in a clear and easy manner so that you can make an informed buying decision.

Choosing right water purifier is extremely important because many diseases are water-borne. In a developing country like India, you cannot rely on filtered municipal water for drinking water, hence the demand for water purifiers.

Water purifiers of different types and each one has its own use depending upon the impurity (TDS) levels and preferences. That is why knowing the difference between RO, UV, UF and MF becomes super important as it will help you in choosing perfect water purifier for our home or office.

So, without further ado, let’s discuss all the main differences between these 4 key water purification technologies.

Table of Contents

Difference Between RO vs UV vs UF vs MF

Suitable TDS Level> 500 PPM< 500 PPM< 500 PPM< 500 PPM
TDS removal90%NoNoNo
Removes physical impuritiesYesNoYesYes
Removes biological impuritiesYesYes (but dead microbes remain in water)YesYes, but not viruses
Water WastageHighNoNoNo
Required MaintenanceHighLowMediumMedium
Remove heavy metalsYesNoNoNo
Remove silicaYesNoYesNo
Membrane0.00001 micronNA0.1 micron1 micron
Water PressureHigh (water purifiers have inbuilt pumps)Tap waterTap waterTap water
Needs ElectricityYesYesNoNo

The illustration below also describes the differences between RO, UV, UF and MF.

RO vs UV

RO stands for Reverse Osmosis and it is one of the most commonly used water purification methods when high purification is required. RO water purifier removes all types of impurities such as dust, dirt, bacteria, viruses, heavy metals and other harmful pollutants and impurities. That’s why RO purification is one of the best methods to purify water especially for home use.

Working of RO is simple. It contains a semi-permeable membrane, through which impure water is passed through great force. This process traps impurities and only water molecules are able to pass through it. It can filter minutest of particle such as calcium, fluorides, cadmium, pesticides, arsenic etc. because its size is 0.0001 micron.

On the other hand, UV (ultraviolet) purification kills only germs such as bacteria, protozoa, viruses etc. UV purification is a simple process where water chamber is equipped with UV lamp / bulb which passes UV-C radiation. This radiation changes the DNA of bacteria and viruses and making them harmless. This results in effective disinfection of water.

Advantages of RO over UV

  • RO purification is one of the most powerful purification methods that can be used in homes. Hence all home water purifiers meant for high TDS water come with RO system. So, if the TDS of water is more than 500 PPM, then the only choice you have is to use RO purification. UV purification always needs low TDS to work effectively.
  • RO is the only method that can remove heavy metals such as pesticides, lead, cadmium, fluorides, zinc, arsenic etc. No other home purification method can remove these toxins. Hence, UV purification is not a good method of purification even when used with UF / MF.
  • Because RO purification is a slow process, most RO water purifiers come with a storage tank. This is helpful because it ensures decent quantity of pure drinking water. Most UV water purifiers do not come with a storage tank.

Advantages of UV over RO

  • RO purification removes more than 90% of TDS from water. This means that along with impurities, essential trace elements are also removed from water during this process. Hence the water becomes unfit for drinking. Hence it is always recommended to buy RO water purifier with TDS controller or mineralizer. Since UV does not change TDS level of water, you need not worry about having a TDS controller in your water purifier.
  • UV purification system is quite simple and affordable. You can buy a UV lamp in couple of hundred rupees. However, RO system does not come cheap and you will have to shell more money to purchase RO system.
  • UV purification is not dependent on an additional pump to increase water pressure, while RO requires a pump to increase water pressure for proper filtration.

Please note that RO and UV are best used when used together because both have different functionalities. This is the reason why most good RO water purifiers come with UV purification.

Also, it is always a good idea to purchase a UV water purifier that either has RO (for TDS more than 500 PPM) or UF / MF (for TDS less than 500 PPM).

UF vs MF

When the TDS of water is low, then it is recommended to use Ultrafiltration (UF) or Microfiltration (MF). However, you will also find UF / MF in RO water purifiers because these are necessary for controlling TDS levels.

Similarities between UF and MF

  • UF and MF both are membrane-based filtration. Which means that water passes through these membranes and particles bigger than the pores get trapped in them, while water passes though.
  • Another similarity between the two is that both the methods are perfectly safe as there is no chemical treatment of water involved.

Differences between UF and MF

One major difference between UF and MF is that their pore size. While there is no fixed pore size for UF and MF, generally accepted pore size for UF is 0.01 micron and for MF it is 0.1 micron.

This difference in pore size determines what types of particles will get trapped in each type of membrane.

Particles that can be filtered by MF membrane are:

  • Algae
  • Bacteria
  • Fungi
  • Protozoa (Giardia lamblia and Cryptosporidium)
  • Dust, dirt, sand particles and other physical impurities

Particles that can be filtered by UF membrane are:

All of the contaminants that MF can remove plus:

  • Endotoxins
  • Colloidal / non-reactive silica
  • Viruses
  • Proteins

Another difference between the two is cost. Usually, MF membrane is slightly cheaper than UF membrane.

Further, you will find several UF + UV water purifiers in the market, while finding a MF + UV purifier can be difficult. This means that stand-alone UF water purifiers are much more popular than MF water purifiers.

Finally, water pressure required for MF is lower than UF. However, still the overall pressure requirement is quite less. Hence, both the filters work decently with tap water.

Please note that if you are confused between MF and UF while purchasing RO water purifier, then you can go with either of them because there is not much difference between the two and most water purifier brands use UF and MF as per convenience.

However, while purchasing a non-RO water purifier, UF water purifier can be slightly better choice given that UF can remove some of the viruses such as influenza virus.

RO vs UF / MF

Before we talk about the differences, let’s understand that there is more similarity between them than dissimilarities. RO and UF / MF are membranes, which means that water passes through them and the particles get trapped in the membranes.

Major difference between RO and UF / MF is in the pore size. Pore size of RO is vastly smaller than UF and MF. This ensures that almost every impurity is removed by RO. This becomes important when TDS of water is high because high TDS is bad for health. RO decreases the TDS of water by 90%, while UF / MF do not reduce the TDS to that extent.

Also, as discussed earlier, only RO can filter heavy metals because of their extremely small size. This makes it necessary to use RO when water supply contain these harmful toxins as UF / MF cannot remove them.

RO uses electricity to operate, while MF and UF do not require power because they can work effectively in very low pressure of tap water.

Choosing between RO and UF / MF is relatively easy. RO technology is meant for water with high level of impurities (TDS), while UF / MF are meant for water with lower TDS.

However, do not get confused when you see water purifiers with RO + UF / MF. Additional UF / MF is added so that some amount of UF / MF purified water is mixed with RO purified water to add back minerals to the RO purified water. Hence, purchasing a standalone RO water purifier is never recommended because it will be devoid of important minerals necessary for human body.


Is it necessary to have UF or MF with RO water purifier?

UF or MF is necessary for effective regulation of TDS in RO water purifiers with TDS controller. Since TDS regulation is important, presence of UF or MF becomes important in RO water purifiers.

Is it necessary to have UV with RO water purifier?

UV is one of the most effective methods for disinfection (removal of germs). Even though RO filtration removes bacteria and viruses, UV works as additional safeguard against harmful germs in water. Hence, UV is present in almost all the RO water purifiers.

When should I purchase UF water purifier?

You should purchase UF (non-RO) water purifier when TDS level of your water is less than 500 PPM.


RO, UF and MF are similar methods of purification involving membranes. While RO is highly effective process, UF and MF have quite similar properties. You can choose the right technology depending upon the TDS levels in your area. To measure the TDS, you can use TDS meter, which can be purchases at quite low prices online.

You will almost always find UV technology in decent water purifiers because it is simple and cost-effective device that disinfects water from bacteria, viruses and other harmful microbes.

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