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What Are Under Sink Water Filters and How Do They Work?
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Updated: February 24, 2023 July 15, 2022
There’s nothing more refreshing than a cool drink of water. All you should have to do is grab a glass, turn on the tap and enjoy.
Unfortunately, for many municipal and well water users across North America, it’s not that easy. Instead, people find themselves worrying about odd odors, unpleasant tastes and even contaminants like lead and arsenic.* You shouldn’t have to stress out every time you turn on the tap.
Luckily, there’s a simple, effective way to enjoy your drinking water again: an under sink water filter. Here’s everything you need to know about these systems, how they work and how to get one for your home.
An under sink water filter may also be called a drinking water system. That’s because it filters water right at the tap so you can count on a clearer, better-tasting drink every time. Unlike faucet-mounted filters, these systems are installed right under your sink — which also means they don’t take up space in your fridge like pitcher filters.
When comparing under sink water systems to other options, you should also consider whole house water filters vs. under sink filtration. The former is a point-of-entry system, which means water is filtered where it enters your home, while the latter is called “point-of-use” because it works at a direct water access point (like your kitchen sink). The main difference is that whole house filters typically are designed to address specific problem water issues, such as chlorine, sulfur, iron or sediment, while under sink filters can address a broad range of potential water issues.
Many under sink water filters work through a process called reverse osmosis. As the name suggests, reverse osmosis is essentially the opposite of osmosis.
To visualize osmosis, imagine a container that’s split down the center. There’s a diluted solution on one side and a concentrated solution on the other, and in the middle is a semipermeable membrane. During osmosis, the diluted solution spontaneously moves through the membrane and into the concentrated solution, forcing the concentration to equalize. This process happens all the time in nature and even in your own body.
Reverse osmosis is different in one big way: While osmosis is passive, reverse osmosis is forced. That means the solution — in this case, your tap water — is being propelled against a semipermeable membrane at high pressure. In this process, particles as small as a single atom can be filtered.
Luckily, you don’t have to be an expert on reverse osmosis to benefit from an under sink water filter. The process happens automatically, all without you lifting a finger. Here’s how it works:
Here are just a few reasons you might choose an under sink filter for your home:
Simply put, an under sink filtration system does the work for you. All you have to do is turn on the tap and enjoy your drinking water.
How Much Do Under Sink Water Filters Cost?
Under sink water filtration systems can have an array of price points. The overall cost depends on factors including how comprehensive the filtration is, the number and type of additional filtration stages or cartridges included, the system’s efficiency, whether smart functionality is included and more.
However, the right under sink system can actually help save money. For example, with Culligan’s Smart Reverse Osmosis System and the Culligan Connect App, you’ll have access to insights including how much you’re saving using a home filtration system versus purchasing single-serve plastic bottles. You can also track water consumption, receive alerts about filter changes, track contaminants reduced and more.
The lifespan of an under sink water filter system depends on a variety of variables, including:
However, each system also has filters, and each filter has its own lifespan. Keeping up with regular replacements is key to helping your reverse osmosis system operate at full capacity. In general, filters should be changed annually, but some systems — like Culligan’s Aquasential® Smart Reverse Osmosis Systems or Aquasential® Reverse Osmosis Systems — have filters that can last two years. Meanwhile, the RO membrane should be checked annually and replaced every three to five years.
There’s a lot to consider when it comes to under sink filtration systems. If you try to guess which one is right for your home, you may end up with a system that doesn’t fully address your needs.
For this reason, the best way to choose a filtration system is to start by having a free, in-home water test and consultation with local water treatment professionals. These tests can give you all kinds of important information, including:
Once your water test is complete, you can use the results to choose the best under sink filtration system for your needs. If you find that you also need to address water hardness issues, don’t worry — under sink filters and water softeners can and should work together. In fact, these solutions complement each other, helping create a better water experience throughout your home.
With an under sink water filter, all you have to do is turn on the tap and enjoy.
*Contaminants may not be present in your water.
**Efficiency is based on 3rd party testing to NSF standards.
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