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Whether your water comes from a private well or a municipal water utility, there’s an ongoing risk that something harmful gets into it.
Water treatment can help reduce and even remove different pollutants from your water, but with so many different technologies on the market, choosing the right filter can be overwhelming.
In this article, we’ll explore important questions like:
What kind of filters are there?
How do they work?
Which filter is best for me?
Choosing a Filter
Many factors go into choosing the right water filter, such as what pollutants you wish to remove, the conditions of the surrounding environment, price range, and lifespan of the filter. While there are a handful of different ways to filter water at home, we will take an in-depth look at the five most popular water purification methods:
Activated Carbon Filters.
Reverse Osmosis Filters.
UV Water Filters.
Activated Carbon Filters
Activated carbon filters (e.g. Brita, PUR and other low-cost counter-top pitcher filters) are very common due to their low cost and ability to remove common water pollutants. Before we dive into what they can and can’t do, let’s take a look at how they work.
How Do Activated Carbon Filters Work?
Activated carbon filters are made out of tiny pieces of treated carbon in granular or block form. The particles are extremely porous with just one gram of activated carbon having a surface area of ~500-3000m2 ! The enormous surface area of the carbon granules makes these filters very effective at removing contaminants out of water via adsorption. Activated carbon filters are capable of removing contaminants anywhere from 0.5 microns to 50 microns in size. Put into perspective, a human hair is approximately 75 microns in diameter.
As water flows through active carbon filters, impurities in the water stick to the carbon and cleaner water results. It is important to note, though, that much of the effectiveness of carbon filters depends on both the flow and temperature of the water. For the best filtration results, activated carbon filters should be used with low pressure and cold water.
What Do Activated Carbon Filters Remove?
Activated carbon filters are most successful at removing the following contaminants:
Volatile organic compounds (VOCs)
Activated carbon filters are also effective at improving the taste and odor of water. For example, chlorine, which is utilized by many municipal water treatment facilities in the disinfection process, is often present in drinking water in small amounts and causes water to taste and smell like bleach. Activated carbon filters remove chlorine in water, enhancing both the taste and odor. In addition, they remove VOCs like hydrogen sulfide gas, which causes the rotten egg smell, thus removing the smell.
Upkeep of Activated Carbon Filters
As water passes through an activated carbon filter, pollutants collect on the carbon. Once the carbon is completely covered with pollutant, it is no longer able to effectively remove impurities from the water. When this happens, the filter must be changed. A few factors affect how long a filter can effectively function, such as how many contaminants are in the water and the volume of water you are filtering.
Each filter comes with a manufacturer’s recommendation, which tells how often you should change your filter. Most activated carbon filter brands suggest that you replace your filter for every 40 gallons of water that passes through, which is approximately every two months.
Reverse Osmosis Filters
How Do Reverse Osmosis Filters Work?
While the term “reverse osmosis” (RO) leaves many confused, the process is relatively straightforward. Simply put, RO systems use a high pressure pump to push water through a series of semi-permeable membranes that allow water molecules to pass through while trapping water-soluble toxins.
Many municipal water systems use RO processes to clean the water that eventually flows from your faucet. However, if your tap water will still has some sediment, minerals, and microbes from the distribution system, you may consider investing in a home RO system.
What Do Reverse Osmosis Filters Remove?
Most RO systems remove 95-99% of total dissolved solids. They eliminate a wide variety of common chemical contaminants and are most effective are removing and improving the following:
Taste, odor, and color
Dissolved organic and inorganic compounds
Despite effectiveness in removing the above contaminants, RO filtration can be a slow and wasteful process in comparison to other treatment processes. For every gallon of purified water produced, domestic RO systems often waste two to three gallons of water.
Upkeep of Reverse Osmosis Filters
Available in a variety of sizes and degrees of complexity, RO systems are sold both as countertop units, which cost around $200, and whole-home systems, which can cost upwards of $12,000.
Though the price tag can be a tough pill to swallow, RO systems consume small amounts of energy and are easy to maintain, as each system lasts for about last for about a year.
UV Water Filters
How Does UV Filtration Work?
Ultraviolet (UV) light has been utilized for decades as a reliable process for microbial disinfection. In the most classical form of UV filtration, water is pumped into a chamber that contains a UV lamp surrounded by a quartz sleeve. The lamp is designed to emit a specific frequency at which, around 254 nm. At this frequency, UV light reliably destroys the DNA of microorganisms. This eliminates the microorganism’s ability to reproduce, rendering it harmless.
Some advantages of UV filtration are that it is chemical free, cost-effective, and fast. In addition, there are no harmful bi-products of UV filtration, and no water is wasted in the purification process.
What Do UV Filters Remove?
If operated properly, UV Water Filters can effectively destroy 99.99% of microorganisms in water.
Microorganisms (such as Coliform bacteria, E. Coli, Legionella, Salmonella, infectious Hepatitis, Cryptosporidium, etc.)
It is important to note that UV filters only remove microorganisms from water. If you want to remove other contaminants, consider combining UV filtration with another purification method or using a different filtration method altogether.
Upkeep of UV Filters
UV filters are fairly simple to maintain- only the UV lamp and its surrounding sleeve, or “filter,” must be replaced annually.
However, in order for UV filtration to work, the water must be clear prior to entering the filter. If water has a high turbidity, UV light cannot reach and kill harmful microorganisms because it is blocked by other particulates. Thus, it is important to have clear water for UV filtration, which can be achieved through proper installation and the utilization of other filtration methods, such as mixed-media, to remove particulates.
Multi-media filters consist of two or more layers of media and are used to reduce the SDI (Silt Density Index) and TSS (Total Suspended Solids) of water. Often, they are used prior to other filtration methods, such as activated carbon and RO filtration, to reduce clogging and increase effectiveness.
How Do Multi-Media Filters Work?
Most multi-media filters have three layers of media. The coarsest, most dense material lies at the bottom, while the finer, lighter material sits on top. Typically, the layers are anthracite, sand, and garnet, with anthracite at the top and garnet on the bottom.
As water filters through, larger contaminants are trapped in the first layer with smaller contaminants catching in the lower layers. This allows for faster flow rates and longer periods of run time between backwash cycles.
What Do Multi-Media Filters Remove?
Particulates as small as 20 microns
Particulates as small as 10 microns (using a coagulant addition)
While many multi-media filters only remove particulates, some utilize media to improve certain water parameters, such as catalytic carbon to reduce chloramine levels.
Upkeep of Multi-Media Filters
Multi-media filters are unlike other filters in that they have the ability to “clean themselves” in a process called backwashing. During backwashing, water flows in the opposite direction, expelling trapped particles and discarding them through the filter drain.
Backwashing should be performed when:
The filter’s pressure gauge reads greater than 10 psi
The turbidity of the filtered water increases by 10%
Water flow is noticeably slower
While chlorine is unsafe to drink in large amounts, in smaller doses, it’s effective in disinfecting water. Chlorination is the process of adding chlorine to drinking water in order to kill harmful bacteria.
How Does Chlorine Disinfection Work?
Chlorine is used as a disinfectant due to its ability to disrupt the activity of harmful microorganisms in water. First, chlorine combines with enzymes in the cell membrane, which damages the membrane and allows chlorine to enter the cell. Once in the cell, chlorine rearranges the DNA and disrupts cell respiration, leading to the death of the microorganism. It is important to note that chlorination is most effective at a low pH and higher temperatures.
Three types of chlorine are used for chlorination:
Sodium Hypochlorite: Better known as household bleach, this compound contains about 5.25% chlorine and is the easiest of the three to manage for residential use.
Calcium Hypochlorite: This compound is most commonly used in residential treatment and is sold in chlorine granules or pellets.
Chlorine Gas: Chlorine gas is sold as a compressed liquid and is the cheapest of the three.
However, because it is hazardous until introduced to water, it is mostly used in municipal facilities.
Chlorination in a residential setting can be conducted using a chlorine pump (most common), suction device, aspirator, solid feed unit, or a batch disinfection system. Each has pros and cons and which system is right for you depends on many factors, such as the source of the water, price, access to electricity, and whether or not you want fixed or varying dosages.
What Is The “Right Amount” of Chlorine To Add?
The amount of chlorine that you add during chlorination depends on which of the three types of chlorine you are using, how much water you wish to purify, and contact time (the period of time between when the chlorine is added and when the water is used). For example, if you are using bleach as your disinfectant, ¼ teaspoon must be added to every one gallon of water.
The amount of free chlorine, or chlorine residual, present in the water indicates whether or not the water is safe to drink. Chlorine residual levels should be between 0.2 PPM and 4 PPM, with optimal concentration between 0.3 PPM and 0.5 PPM.
Chlorine residuals within optimal range indicate that:
Enough chlorine was added to the water to kill harmful microorganisms
Recontamination during storage didn’t occur
Too much chlorine wasn’t added
What Does Chlorine Filtration Remove?
Upkeep of Chlorine Disinfection
Different chlorination mechanisms require varying maintenance routines; however, all systems require chlorine supplies to be refilled periodically.
Water Filters Recap
Water filters, air filters, and even Instagram filters tend to make things better, depending on which one you choose. Many factors go into choosing the right filter for you and your water, but with the right filter, you have the ability to greatly enhance your health and the health of those you love. So, go get yourself a filter…. Water you waiting for!?
Late to Regulate | SimpleLab Tap Score
What Are Emerging Contaminants? – SimpleLab Tap Score
Chloramine, Chlorine, Lead and Pipes: How Water Treatment Turned Toxic – SimpleLab Tap Score
What Are VOCs and Are They in Your Drinking Water? – SimpleLab Tap Score
How Does the Environment Impact Your Health?– SimpleLab Tap Score
Water Chlorination: The Visible Impacts | SimpleLab Tap Score
Sulfur Smells: Why Does My Water Stink Like Rotten Eggs? | SimpleLab Tap Score
7 Heavy Metals Everyone Should Test For | SimpleLab Tap Score
What Is Reverse Osmosis (RO)? – SimpleLab Tap Score
Do I Need a Water Softener? – SimpleLab Tap Score
7 Pathogens That Contaminate Drinking Water | SimpleLab Tap Score
Chlorine and Chloramine: Two Ways to Disinfect – SimpleLab Tap Score
Nitrites, Nitrates, and Your Health – SimpleLab Tap Score
Sources and References▾
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