Clean drinking water is an essential part of daily life, so it’s no surprise humans have created many ways to treat water. In fact, water filtration systems have long been a part of civilization, dating as far back as ancient times. Filter technologies vary greatly but it is difficult to crown one system as superior, since the different types serve different purposes.
Some filtration systems rely on several technologies, while others are effective on their own. Each type removes different impurities, so it’s important to get the right type of filter for the type of contaminants you wish to eliminate. Keep in mind that even within the same type of technology, the contaminants removed can vary. For example, some carbon filters remove chlorine while others do not.
Carbon has long played a role in water purification, with some evidence suggesting the ancient Egyptians used carbon in water storage barrels. Carbon filtration can improve the taste, odor and color of water, as well as remove or reduce contaminants such as chlorine and pesticides.
In a carbon filter system, water is filtered through carbon to remove impurities through chemical adsorption. The adsorption process differs from absorption in that materials adhere to a solid, rather than permeating it. During carbon filtration, contaminants are trapped by activated carbon while the water passes through. Activated carbon is a form of treated carbon that is highly porous with a large surface area, making it ideal for filtration. The most common types of carbon filtration systems are granular activated filters (GAC) and powdered block filters, the latter of which removes a greater number of contaminants.
This technology is used in water purification and water softeners. In this system, water passes over an ion-exchange resin composed of many tiny beads. The unwanted ions are trapped in the resin and another ion is released, hence an “exchange” is made. For example, as part of a water purification process an ion exchange might replace copper particles with sodium. As with carbon, the resin’s beads are highly porous and have a large surface area.
Mechanical filters remove solid particles from water, such as sediments and cysts. A mechanical filter is covered in small holes that water passes through. Particles are then trapped in a synthetic material inside of the filter, such as nylon. Mechanical filtration is commonly used in aquariums to improve water clarity and remove fish waste. On their own, mechanical filters do not remove chemical contaminants.
In this system pressure is used to flow water through a semipermeable membrane, which traps particles and allows the water to pass through. Reverse osmosis can turn saltwater (or any water source) into drinkable or potable water. This technology is often used as part of a more complex filtration system using several technologies.
Water is considered “hard” if it contains too many minerals. Hard water is undesirable since it can cause build up in pipes and appliances. Water softening uses an ion exchange to remove or lower ions that cause hard water, such as magnesium or calcium. Water softeners do not remove chemical contaminants.
While there are plenty of products available on the market, not all are created equal. We hope this information can help you understand what goes into common water filters and which one might work best for your home and your personal needs.
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