RO vs UV vs UF vs MF Water Purifiers – What is the difference?

There are plenty of water purifiers in the market. Understanding each type of water purification technology can be difficult. Therefore, we have come up with this comprehensive guide to help you understand difference between each type of technology better.

In this post we will explain common water purification technologies – RO (Reverse Osmosis), UV (Ultraviolet), UF (Ultra-filtration) and MF (Micro-filtration), and the difference between them.

Once you understand the difference between the RO, UV, UF and MF water purification technologies, you will be able to choose the best water purifier that is best suited for your home or office.

This chart below lists all the key differences between RO, UV, UF and MF.

RO vs UV vs UF vs MF Water Purifiers

Needs ElectricityYesYesNoNo
Filters BacteriaYesYesYesYes
Filters VirusYesYesYesNo
Input Water PressureHighestLowMediumLow-Medium
Removes salts and heavy metalYesNoNoNo
Removes TDSYesNoNoNo
Water WastageYesNoNoNo
Filters ImpuritiesYesNoYesYes
Pore Size0.0001 micronNo pores0.01 micron0.1 micron
MembraneNonporous asymmetricNo membranePorous asymmetricPorous isotropic

This chart can be slightly confusing. You can take a look at this image to understand how these technologies differ.

RO vs UV vs UF vs MF

RO, UF and MF are similar in functioning. All of these are semi-permeable membranes with small pores. Water passes through these pores, while impurities are blocked on surface of the membrane.

RO vs UF vs MF

The primary difference between RO, UV and MF is in the pore size of each membrane. RO membrane is the smallest at 0.0001 micron (1 micron = 0.0001 cm). Average size of a UF membrane is 0.01 micron, while average size of MF membrane is biggest among the three at 0.1 micron.

ro vs uf vs mf


MF or micro-filtration removes suspended solids and bacteria from water. Germs such as E. coli (causes diarrhoea), Cholera bacteria, Staphylococcus (can cause infections) are filtered by MF filtration.

MF purification does not require electricity for functioning and it can work in quite low water pressure. Since MF has larger pore size, it cannot filter virus and toxic elements such a heavy metals

MF is usually used along with other purification methods such as UV and RO. Also, it is not sufficient for water with high TDS because the impurities easily pass through it. Water with TDS less than 500 is ideal for MF purification.

Transfer mechanism involves sieving and absorption process. This means that the impurities migrate by convection.

Things MF can filter-

  • Algae
  • Bacteria
  • Protozoa (commonly cause stomach infections)
  • Sediment, including sand, clay and complex particles


UF and MF are quite similar in effectiveness. One main difference is that UF membrane size is smaller, which makes it slightly more effective than MF. Thus, UF can filter out filter suspended particles, bacteria and viruses. UF can even finer particles such as colloidal silica, which MF cannot.

Just like MF, UF does not need electricity to filter water, but requires slightly higher water pressure because of its smaller pore size.

Pore size of UF membrane is smaller than MF and it can filter some viruses (such as influenza virus) but it still cannot filter toxic elements such as Lead, Arsenic, Cadmium etc. Also, just like MF, it is not very effective in water with high TDS levels. Similar to MF, water with TDS less than 500 is ideal for UF purification.

Transfer mechanism is sieving and preferential absorption. This is different from MF. Another difference is the pressure requirement. MF requires 0.5 to 5 atoms of pressure, while it is 1 to 10 for UF.

UF can filter following particles:

  • Algae
  • Bacteria
  • Protozoa
  • Sediment
  • Endotoxins
  • Plastics
  • Proteins
  • Silica
  • Silt
  • Some Viruses


RO membrane is one of the most effective ones out there. Its pores are so small that dissolved salts, heavy metals, organic impurities, minerals, bacteria and even virus get trapped in it. Since the size is so small, it requires extra water pressure to let water pass through the membrane. RO technology has one major drawback and that is it wastes lot of water. For every litre of water filtered, it wastes 2 to 3 litres of water. And this water cannot be used for drinking.

Since it is the most effective purification, it is ideal for water with TDS level of upto 2000 ppm.

Since RO removes all the natural minerals and dissolved salts in water, it may not taste like natural water. Also, because the water will lack minerals, it is not healthy for consumption. Therefore, it is always recommended to purchase RO purifier with a TDS controller or a mineralizer.

Transfer mechanism is diffusive. It means that the impurities migrate by diffusion process.

For more information on RO, you can check out types of water purifiers.

RO vs UV

RO and UV are two different technologies. RO is necessary to eliminate dissolved impurities while UV deactivates micro-organisms in the water.

Filters dissolved impuritiesKills germs
Expensive technologyCost Effective technology
Needs high maintenanceDoes not need high maintenance
Does not necessarily needs UVCannot be used standalone
Requires very high water pressureCan work in low water pressure
Can change taste of waterNo effect on taste of water

UV water purification technology only kills germs. It produces germicidal UV-C radiation that damages the DNA of bacteria and virus, thus deactivating them and preventing them from reproducing.

Frequently Asked Questions: RO vs UV vs UF vs MF

UF vs MF Filtration- Which is better?

UF filtration is better than MF filtration because it can filter finer particles. For example, UF can filter some viruses such as influenza viruses, but MF cannot filter viruses because of larger pore size.

UF vs UV Filtration- What is the difference?

UF is a membrane based filter than blocks impurities such silica, proteins, plastics, endotoxins, and smog and/or fumes and some types of viruses. On the other hand, UV only kills microorganisms (protozoa, bacteria, viruses) with the help of UV radiation that is emitted from the UV lamp.

Which is the best water purification technology?

RO (Reverse Osmosis) is currently the best purification technology for water with high TDS, while UF/MF + UV is best purification technology for water with low TDS.


RO, UV and MF are similar technologies with different levels of filtration. MF has larger pores so it blocks suspended particles and bacteria, UF has smaller pores to block everything that MF can plus virus, while RO membrane filters almost every impurity from the water.

On the other hand, UV is a different technology that involves treating water with UV radiation to kill microorganisms.


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