Which water purifier should you buy?

In our daily lives, we often consume water without much thought of its quality or purity. Yet, contaminants like lead, chlorine, and others can leach into our water supply, posing a threat to our health. While municipal treatment plants work tirelessly to supply clean water, some impurities can slip through. That’s where water purifiers come in.

These handy systems offer an extra layer of filtration, ensuring the water you drink is as clean and safe as possible. In this guide, we’ll break down the different types of water purifiers and help you decide which one is the perfect fit for your needs.

Types of water purifiers

Depending on the water purification methods, water purifiers can be classified into 5 types:

1. Reverse Osmosis (RO)

2. Ultraviolet (UV)

3. Ultrafiltration (UF)

4. Activated carbon

5. Sediment filter

1. RO water purifier

The Reverse Osmosis (RO) water purifier is one of the most popular choices in Indian households for its effectiveness in water purification. Its method is simple yet effective: forcing water through a series of four filters. First up is the sediment filter, which rids the water of pesky particles like dirt and silt. Then, the carbon filter removes chlorine and other impurities that could compromise the RO membrane’s functionality. 

Following that, comes the semipermeable membrane, featuring pores of 0.0001 microns, which plays a crucial role by trapping dissolved solids like arsenic, fluoride, lead, chlorine, nitrates, and sulphates, leaving behind purified drinking water. Subsequently, the polishing filter is employed to remove any remaining odours, ensuring the water’s purity. 

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With each stage operating under high pressure, the RO system forcefully expels dirt, microorganisms, and unwanted dissolved solids, though it can also remove some beneficial minerals. This process notably reduces the Total Dissolved Solids (TDS) value, particularly in hard water. RO water purifiers can be further classified into types depending on where they are mounted: wall-mounted, tabletop, under-sink, or under-counter RO water purifier.

2. UV water purifier

UV (Ultraviolet) water purification represents a well-established and effective technology renowned for its capacity to eliminate disease-causing microorganisms such as bacteria, viruses, and cysts. This eco-friendly method operates without the need for chemical additives during the purification process.

Your water purifier has a chamber with a UV lamp. As water flows through, the UV light disrupts the DNA structure of any microorganisms, rendering them inactive and unable to reproduce. While the inactivated bacteria and viruses remain in the water, they are no longer harmful. The efficiency of UV water purification is particularly notable for its suitability in treating water with low TDS, including sources like lakes and rivers. 

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Offering rapid purification without the need for extensive setup time, UV purifiers activate immediately upon switching on, and are economically viable due to their minimal power consumption. However, it is important to note that UV technology alone may not be enough to completely purify tap water, as it does not address the removal of contaminants, or the softening of hard water characterised by high TDS levels. This is why UV is often coupled with other technologies, like RO or UF in water purifiers.

3. UF (UltraFiltration) water purifier

Ultrafiltration (UF) purifiers reign supreme in India and are a budget-conscious choice for many households, thanks to their simple yet effective design. They utilise a simple yet clever filtration method, often relying on gravity to gently remove bacteria, viruses, dust, sand, and even chlorine from your water. Unlike reverse osmosis (RO) systems that remove dissolved contaminants, UF focuses on the physical separation of larger particles. 

Some UF water purifiers work without electricity and don’t use any chemicals, making them ideal for removing bacteria and viruses from water with low chemical contamination. However, UF does not remove dissolved salts that cause hardness in water, so the water will remain hard after treatment. That’s why UF technology is often combined with UV or RO water purifiers.

4. Activated carbon water purifier

Activated carbon is a highly porous form of carbon, typically made from coconut shells, wood, or coal. It is processed to increase its surface area, making it highly effective in adsorption. During adsorption, contaminants, such as chlorine, pesticides, and organic chemicals that cause bad taste and odour, stick to the surface of the activated carbon. As water flows through a filter containing activated carbon, these contaminants are trapped, resulting in purified water. 

While activated carbon tackles common culprits, it can’t remove everything. For elimination of heavy metals or serious waterborne diseases, additional filtration might be needed. But for everyday taste and odour improvement, activated carbon still remains a good choice.

5. Sediment filter

A sediment filter is a pre-filter used alongside RO and UV systems. Sediments usually comprise any solid particles suspended in water, including rust flakes from pipes, sand, mud, and assorted debris, leading to decreased water clarity, termed turbidity. The sediment filter effectively traps these unwanted particles. It is typically made from cotton or polyester fibres and housed in a cylindrical form within a sealed plastic container. 

As water travels through sediment filters, these contaminants are trapped and held by the porous materials constituting their structure. This process enhances water clarity, reducing visible particles and enhancing the aesthetic quality of water for various applications, notably drinking. Typically installed at the inlet of water purifiers, the sediment filter captures dirt and dust particles before water undergoes other purification processes.

Which water purifier should you buy?

From knowing about your water TDS to your budget, there are several things to consider before buying a water purifier. This step-by-step guide will help you understand what’s important for your needs and safety.

Step 1: Knowing your water quality

The first step is to understand your water quality. This will help you choose the right purifier and be aware of your water source’s reliability. Homes can have municipal supply, borewells, natural sources, water tanks, or a combination. Knowing your water source helps identify potential contaminants. Municipal water typically has lower TDS and may contain chlorine. Borewell water often has higher TDS and may contain minerals, bacteria, or even arsenic.

You’ll also need to check for Total Dissolved Solids, which indicates the amount of dissolved minerals and impurities in your water. A higher TDS signifies harder water. A simple TDS-meter is readily available online or at hardware stores. Contact your local water authority or certified labs for a more comprehensive analysis. 

Step 2: Identify core filtration technology that you need

The next step is to identify the best technology for your household.

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Here are some tips based on TDS levels and considering common impurities:

1. High TDS (over 300 ppm):

RO: Ideal for hard water, RO removes a wide range of impurities, including minerals, heavy metals, and bacteria. However, RO can also remove some beneficial minerals.

RO+UV: This combination offers the benefits of RO with added protection against bacteria and viruses using ultraviolet light (UV).

2. Low TDS (below 300 ppm):

UF: A good choice for removing bacteria and some impurities without affecting mineral content.

UV: Effective in eliminating bacteria and viruses but doesn’t remove dissolved solids. This is suitable if your primary concern is bacterial infection.

Here are a few recommendations from the World Health Organization (WHO) and Bureau of Indian Standards (BIS) around the recommended purification technology according to different TDS levels in water supply:

1. 0  to 90 PPM:  Gravity filters, MF or UF.

2. 90 to 200: UF or NF20

3. 200 to 350: UF or NF40

4. 300 to 600: NF60

5. 600 to 1500: NF80

6. >1500: RO

Step 3: Explore features

Once you have narrowed down on the filtration type you need, you can explore various features available.

1. Storage tank: Provides a constant supply of purified water, especially helpful during power cuts. Look for a food-grade, non-toxic tank, preferably made of stainless steel.

2. TDS controller (in RO purifiers): Allows you to adjust the output TDS level, ensuring you retain some beneficial minerals in the water.

3. Informative display: Provides valuable information like water level, filter status, and even TDS level. Look for models with filter change alerts for timely maintenance.

4. Activated carbon filter: Improves taste by removing chlorine and organic impurities that can cause bad odour.

5. Sediment pre-filter: Protects the RO/UF membrane by removing coarse and fine particles like dirt and dust, extending its lifespan. This can even be added to existing purifiers for better performance.

6. Additional features: Look for optional features like auto-shut off, taste adjusters, and smart notifications.

Step 4: Know your budget

Buying a water purifier is an investment. Consider the cost of regular filter replacements for ongoing maintenance and factor in potential repairs. While some brands might have higher upfront costs for filters, they may offer better quality and readily available replacements. Look for brands with good after-sales service.

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This covers the different types of water purifiers and offers a brief insight into choosing the right one for your home, considering water quality, budget, and your needs.