What Is The Significance of UF In Water Purifier?

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RO, UF and UV are some of the common terms you come across when you are out to purchase a water purifier. Out of them, UF a.k.a ultrafiltration can either be a gimmick or indispensable depending on the other features. We will look into it in detail. But, first, let us understand what UF is and how it works.

Ultra Filtration ( UF)

filters in RO water purifier
Filter cartridges in an RO water purifier

Amidst the array of filter cartridges utilized in these purifiers, Ultrafiltration, often referred to as UF, stands out significantly. They find their place not only in Reverse Osmosis (RO) water purifiers catering to regions with high Total Dissolved Solids (TDS) water supply but also in regular purifiers serving areas with municipal water sources.

At its core, UF operates as a membrane filtration system that exerts pressure to drive water through a semi-permeable membrane, acting as a robust barrier against suspended particles. These particles encompass a wide range, including viruses, bacteria, metals, and other solids. It’s important to note, however, that UF cartridges are unable to eliminate dissolved solids. This means that while they effectively eliminate various suspended impurities, they do not reduce the TDS (Total Dissolved Solids) content of the water, for which an RO membrane is necessary.

It’s not uncommon for Ultrafiltration (UF) and Microfiltration (MF) to be used interchangeably, but a noteworthy distinction exists between the two. In UF, the membrane’s pores are 1/10th of a micrometer in size. In contrast, the name Microfiltration aptly describes its pore size, which is one micrometer. The significance of this disparity becomes apparent – UF’s finer pores make it more adept at capturing even smaller particles with greater efficiency than microfiltration.

Related reading: How To Choose A Water Purifier For Your Home?

UF In Water Purifiers For Municipal Water Supply

UF in water purifiers

Municipal water supply systems are designed to provide safe and treated water to our homes, having undergone thorough processing to eliminate pathogens and dissolved solids. However, despite these measures, the journey from the treatment plant to our taps is not without potential challenges. The aging pipes that transport the water can introduce contaminants, posing a concern for water quality. These pipes, worn by time, can release metal particles into the water or allow pathogens to infiltrate the supply.

In such scenarios, opting for a UV-UF water purifier is a prudent choice. The UV chamber within the purifier plays a crucial role by effectively neutralizing pathogens present in the water. This ultraviolet light sterilization process disrupts the DNA of bacteria, viruses, and other microorganisms, rendering them harmless and incapable of reproducing.

Simultaneously, the UF cartridge in the purifier takes center stage in eliminating suspended particles, including pathogens and metal fragments. Acting as an advanced sieve, the UF membrane’s incredibly small pores prevent these unwanted contaminants from passing through. This two-pronged approach—UV decontamination and UF filtration—guarantees that the water emerging from the purifier is purified to a degree that makes it safe and suitable for consumption.

UF In Water Purifiers For Borewell Water Supply

RO water purifier

Borewells, tanker-delivered water, and underground sources are often characterized by high levels of Total Dissolved Solids (TDS). This TDS comprises various dissolved substances such as carbonates, fluorides, calcium, magnesium, among others. While Ultrafiltration (UF) membranes cannot tackle TDS removal, Reverse Osmosis (RO) membranes are indispensable as they not only eliminate TDS but also suspended particles.

So, why then do RO water purifiers incorporate UF membranes if the RO membrane appears to address all concerns? As always, the intricacies lie within the details. Let’s delve into the nuances.

As water passes through the RO membrane, it effectively strips away nearly all dissolved solids. However, drinking water with extremely low TDS levels isn’t conducive to good health. Consequently, water purifiers integrate diverse technologies to raise TDS levels to an optimal range.

In the first category of water purifiers, a mineral cartridge introduces controlled levels of calcium, magnesium, and other minerals into the water during the final purification stages. In such cases, UF membranes do not play a pivotal role. Brands often market this as an additional purification layer to ensure the utmost purity, though it’s not a necessity.

The second category of water purifiers employs a manual TDS controller instead of a mineral cartridge. This involves mixing a portion of raw water with water that has undergone RO filtration to elevate the output water’s TDS. Typically, in these purifiers, the raw water undergoes UF filtration before mixing to eliminate pathogens or metals. Even if the UF membrane is positioned in the final purification stages, it fulfills the same purpose.


To wrap things up, remember that when you’re looking out for a water purifier with a Manual TDS (MTDS) controller, make sure it’s got a UF filter in tow. This nifty addition ensures any raw water getting into the mix has been treated right. This little detail becomes even more important during times when groundwater contamination tends to spike, like during summers and monsoons. Going for a purifier without UF filtration in such situations might not be the safest bet for your health.

On the other hand, if a brand sells water purifier with mineral cartridge and offers the same model with UF at a higher price, it is better to opt for the former. The latter doesn’t offer any significant difference in water quality that warrants the extra expense.

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