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Do Water Filters Work?

Do water filters work? The short answer is yes! Water filters are highly effective at filtering contaminated water. The effectiveness of the water filter depends on what contaminants are in the water and what type of filtration method is used. Gaining a better understanding of what types of contaminants water filtration systems are able to remove will help illuminate the real-world effectiveness of your water filtering system.

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What is in Your Drinking Water?

Tap water may contain contaminants that you may not want to consume, which is why many people turn to water filtration systems. The water coming from your tap may contain levels of impurities that violate long-standing regulations put forth in the 1974 Safe Drinking Act. Not all tap water in the United States is poor quality containing harmful contaminants, but understanding if yours is and how to treat it is important.

To illustrate this, a recent study by the nonprofit Environmental Working Group (EWG) found that the drinking water for 7.5 million California residents contained dangerous, harmful levels of fluorinated chemicals known as PFAS. PFAS are used in firefighting foams, nonstick coatings, and food packaging. 

The study found that roughly 40% of the municipal water systems tested had harmful levels of PFAS that exceeded the Environmental Protection Agency’s (EPA) thresholds for safe exposure. PFAS in even low doses has been linked to a number of negative health impacts, including liver and thyroid disease and increased risk of certain cancers.

It isn’t uncommon for similar violations to occur for other contaminant substances. The most notable recent drinking water crisis involved extremely elevated levels of lead in Flint, Michigan. Lead and other heavy metals are dangerous contaminants that can leach into drinking water from old pipes used in aging water delivery infrastructure.

Common contaminants found in drinking water include:

  • Bacteria and viruses such as cholera, typhoid, salmonella, coliforms, and Legionella.
  • Disinfectants used in water treatment, such as chlorine and bromine.
  • Industrial chemicals like PFAS.
  • Heavy metals like arsenic and lead.
  • Nitrates from farm and lawn runoff.

What do Water Filters Remove?

Different types of filtration systems remove different types of contaminants. Because of this, many water filtration systems combine different filtration methods to capture a broad array of contaminants and remove impurities. An outline of the strengths of each type of filtering method not only explains how do water filters work, but also how overlapping filtering methods can produce better results.

Let’s explore what is a water filter and the three most common water filtering methods for residential use.

Reverse Osmosis

Reverse osmosis (RO) is one of the most effective methods to reduce harmful bacteria and produce safe drinking water  In an RO system, contaminated water is forced through a membrane that contains very small pores. The pores are small enough to let through water molecules, but not large enough to let through other solids and particles.

Reverse osmosis systems are great at removing substances that are larger than a water molecule, including sodium, nitrates, and the mineral and metal ions like calcium carbonate and lead that contribute to water hardness. RO systems are less effective at removing any other contaminant whether that be bacteria or chlorine.

Activated Carbon

Activated carbon is a type of charcoal that has been treated with oxygen to increase the surface area of the carbon. As water passes through activated carbon water filters it attracts and traps any contaminant or impurity that exists.

Activated carbon water filters are effective at removing disinfectants, pesticides, and industrial solvents. This filtration method is also used to remove bad odors and taste from the water. Activated carbon water filters are less effective at removing the mineral ions that contribute to water hardness, sodium, fluorine, and nitrates.


Ion-exchange systems are often referred to as water softening systems because they are used to remove the mineral ions and metals that contribute to water hardness. These systems contain a tank filled with negatively charged resin beads. As water flows over the resin beads, the mineral ions attached to the water molecule are attracted to the resin and replaced with sodium ions.

Ion-exchange systems are effective at removing mineral ions and heavy metals from water, but they won’t remove disinfectants used in water treatment, sediment, fluorine, or industrial chemicals and solvents.

Putting it all Together

Each water filtering method has different advantages, which is why many residential filtration systems combine multiple filtration methods into the same system. For example, the Rayne Clear reverse osmosis drinking water system combines a water reverse osmosis component with a sediment and carbon pre-filter and activated carbon post filter. This allows the system to capture a wider spectrum of total dissolved solids (TDS), contaminants, and bacteria than simply using activated carbon water filters or water reverse osmosis systems on their own.

Due to the fact that some filtering methods are effective at removing certain types of contaminants and not others, it is important to understand exactly what contaminants are in your water before you invest in a water filtering system for your home. This will allow you to choose the filtration system or combination of filtration systems that are right for you. 

The first step towards achieving purified water that tastes better and contains fewer contaminants is to talk to a water filtration expert. Rayne Water has been conditioning water since 1928, so our helpful staff has the expertise to guide you towards the right system for your needs.

We have many SoCal locations and can provide water softeners in Bakersfield all the way down to San Diego! Give us a call today to schedule a free two month trial!

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  1. Hamers, Laurel. “Drinkability.” Science News 194, no. 10 (November 24, 2018): 18.