How Do Water Filters Work ?

how do water filters work

Water filters work by acting like a super-fine strainer or sieve. The filter component of these water filters is porous. When water passes through it, the dirt and impurities get filtered out while clean water to get through. Different filters use different materials and methods, but they all aim to do the same job – make your water healthier and tastier.

In this blog, let us explore how water filters work and how they can make a significant difference in your daily life.

What is a Water Filter?

A water filter is a device that helps remove impurities, contaminants, and particles from water by trapping or chemically neutralizing harmful substances, to make it safe and suitable for drinking, cooking and other household uses.

What Are the Different Types of Water Filters?

There are different types of water filters that serve the purpose of purifying water using various techniques.

  • Mechanical filters

Mechanical water filters use physical barriers or screens to remove particles, sediment and debris from water. These water filters work on the principle of physically trapping impurities in the water, preventing them from passing through the filter and ensuring that cleaner water flows out.

They are commonly used in various applications, including home water filtration systems, swimming pool filters and industrial processes where removing larger particles from water is essential. They are an important part of ensuring water quality by removing visible impurities and improving the taste and clarity of water.


  • Activated carbon filters

Activated carbon filters use activated carbon to remove impurities from water. Activated carbon is porous in nature. When water passes through these filters, the impurities stick to the activated carbon, leaving it cleaner and fresher. Apart from purifying, activated carbon filters make drinking water taste better as well.

Remember, it is important to replace the activated carbon in the filter when it gets full to keep it working well.

  • Reverse Osmosis (RO) filters

RO water filters work using the process of reverse osmosis. These filters consist of a semipermeable membrane that has extremely tiny holes. Pressure is applied to push water backwards through the membrane, which is against the natural flow of water – reverse osmosis. By applying pressure, the clean water moves from the impure side to the pure side, leaving behind all the dirt.

RO filter makes drinking water safe to drink and taste better.

  • Ultraviolet (UV) filters

UV filters use ultraviolet light to disinfect water by killing harmful microorganisms, like bacteria, viruses, etc. However, they are not capable of removing other impurities like dirt or chemicals. Therefore, UV filters are often used alongside other filtration methods, like activated carbon or RO, to address a wider range of water quality issues.

It is important to replace the UV lamp when it wears out so that the filter works effectively.

  • Ion exchange filters

Unlike most water filters, ion exchange water filters do not actually filter out contaminants from water. Instead, it is used to soften hard water. The filter comes with tiny resin beads that attract and hold onto ions and exchange minerals, like calcium and magnesium that make water hard with other minerals, like sodium or potassium.

Ion exchange water filters are particularly useful for dealing with hard water problems. By exchanging hard minerals for softer ones, these filters help protect your plumbing and make it easier to clean.

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How do Water Filters Work?

Water filters use various mechanisms to remove impurities and contaminants from water. These mechanisms include physical filtration, chemical adsorption, ion exchange, reverse osmosis and more. Depending on the type of filter and its specific design, the filters can effectively target different contaminants, providing clean, safe and better-tasting water that can be used for various purposes.

Mechanical filtration

The fundamental concept behind mechanical filtration is to use a physical barrier to eliminate sediment, dirt or any suspended particles present in the water. Mechanical filters can vary from a simple mesh that screens out larger particles to a ceramic filter with an intricate pore structure designed to meticulously remove even tiny, disease-causing microorganisms.

Filters that use mechanical filtration typically receive a micron rating to denote their effectiveness in capturing particles based on their size. For example, a 5-micron filter can catch things you can see, a 1-micron filter can trap particles that are not visible to the naked eye, but a microscope, while a 0.5-micron filter can even catch tiniest of particles.



Activated carbon filters use absorption to filter out impurities from water. They are porous and the pores filter out impurities and chemicals, like chlorine, making your water taste and smell better. Some filters use carbon blocks, which are even better at this and can also catch small particles.

Ion exchange

This is like a trade. Hard minerals in the water, like calcium and magnesium, get swapped with other ions, especially sodium or hydrogen. This makes the water softer and reduces limescale.

Reverse osmosis

This method is like pushing water through a super-fine membrane that only lets water molecules pass. It is great for removing a whole lot of impurities from the water, but it can be a bit wasteful, causing some extra water to go down the drain.

Benefits of Water Filters

With water pollution being prominent today and the unavailability of natural water sources, especially in urban areas, water filters are a blessing.

  • Improved water quality

Water filters remove impurities, resulting in cleaner, better-tasting water.

  • Healthier drinking water

Water filters help remove harmful chemicals and microorganisms, making the water safe to drink.

  • Cost-effective

A water filter is like a one-time investment. Once you buy it, you won’t have to worry about spending money to buy bottled water every time. The only expense after buying a water filter is its maintenance which happens once in a few months.

  • Environmental benefits

When you have a water filter, you won’t need bottled water anymore. This means decreased plastic waste, contributing to a healthier planet.

  • Convenience

With a water filter, you have access to clean water right from your tap, eliminating the need to buy and store bottled water.

How Long Will It Take to Filter Water?

Most water filters can produce a certain amount of filtered water per minute. The time it takes to filter water depends on the type of water filter you’re using and the filtration capacity.

Therefore, it is essential to check the specifications of your water filter to understand its flow rate and capacity. Some high-capacity filters may even take longer to initially fill, but they provide a continuous supply of filtered water.

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How Often Do We Need to Change the Filters?

The frequency of filter replacement depends on several factors, including the type of filter, the volume of water filtered, and the quality of the source water.

Activated carbon filters typically last for 2 to 6 months, depending on usage and water quality. Many filters even have indicators to remind you when it is time for a replacement.

RO filters have multiple stages, each with its own lifespan. The sediment and carbon pre-filters may need replacement every 6 to 12 months, while the RO membrane can last 2 to 3 years.

In UV filters, UV bulbs should be replaced annually to maintain their effectiveness.

The resin beads in ion exchange filters typically last 2 to 3 months, depending on the hardness of the water. Some models have an indicator that changes colour when it is time to replace the resin.

It is always best to go by the manufacturer’s recommendations for filter replacement intervals, as they can vary between brands and models. Regularly changing filters is crucial to maintain water quality and the effectiveness of your water filter.

Where Do We Buy a Water Filter?

When choosing where to buy a water filter, consider factors like product availability, price and customer service. Also, do research and compare different brands and models to find the water filter that best suits your water quality needs and budget.

You can buy water filters from different retail locations and online stores. Retail locations include hardware stores or appliance stores. You can also purchase them from ecommerce platforms or manufacturers’ websites, which may provide additional product information and support.

How Much Does It Cost to Buy a Water Filter?

The cost of a water filter can vary significantly depending on the type of filter, brand, capacity and features. A water filter of 10 L capacity generally costs between ₹12,000 and ₹25000.

While deciding on your budget to buy a water filter, do not consider the initial purchase price alone. You should also consider ongoing maintenance costs, such as filters. Another important factor is your requirements. You should be able to balance your budget with your water quality needs to find the right water filter.

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What Are the Popular Brands of Water Filters?

When choosing a brand, consider your specific filtration needs, budget and the availability of replacement filters. Proper research by reading customer reviews and seeking recommendations can also help you make an informed decision.

Several reputable brands offer high-quality water filters and filtration systems. Here are some popular brands known for their reliability and performance:

  • Eureka Forbes – Aquaguard
  • Livpure
  • HUL Pureit
  • V-Guard
  • Faber
  • Blue Star
  • Kent
  • TATA

Water filters play an important role in making sure that the water you drink or use for houseful needs is clean, safe, and free from contaminants. Whether you opt for a basic model or an advanced one, make sure that it fits your needs and budget. By investing in the right water filter, you can enjoy improved water quality, better health and peace of mind knowing that your water is pure and safe for consumption.


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