If you’re worried about contaminants in your drinking water or just don’t think it tastes as good as it should, it might be time to invest in a product that can treat your water.* Filters that sit in pitchers or connect to a faucet or refrigerator are popular options, but there’s another choice that deserves your attention: reverse osmosis.
Traditionally installed under your kitchen sink, reverse osmosis filtration systems work differently than the others – they have much more in-depth filtration capabilities, which is why they’re worth the additional upfront investment.
All the water filters referenced above use activated carbon to reduce contaminants, but the kind of carbon they use is different, and so is the design of each system. Additionally, it’s important to know that standard refrigerator, faucet and pitcher filters rely mainly on basic carbon filtration, while typical RO systems offer multiple stages of advanced filtration (more on that in the next section).
Here’s how carbon filters work: The carbon absorbs contaminants, and the more contact time it has with them, the more it can reduce. That’s why surface area comes into play – the bigger the carbon surface, and the longer the water is in contact with it, the better filtration it can provide.
From this perspective, reverse osmosis systems are the best choice. Not only do they have large carbon filters, but the water is pushed through the filters with pressure, so the carbon they use can be packed tightly in a solid block with only tiny holes.
Pitchers are on the opposite side of the spectrum. They have limited space, so their carbon filters must be smaller. In addition, they rely on gravity, rather than water pressure, to push the water through the carbon. Thirsty users would never want to wait for water to finally flow through a solid block of carbon, so carbon in pitchers is typically in the form of loose granules.
Since RO systems have more surface area of carbon than pitcher filters, the RO has better filtration capability.
Faucet filters and refrigerator filters fall in the middle in terms of filtration efficacy. Filters that mount on faucets are also small, but they can perform better because they have the benefit of water pressure. Fridge carbon filters can be bigger and, as a result, can have higher levels of contaminant reduction than filters in pitchers and on faucets. Yet standard refrigerator filers still don’t measure up to the level of filtration RO systems offer.
While standard refrigerator, faucet and pitcher filters rely solely on carbon filtration, it’s only one of multiple stages of filtration that typical RO systems use to make tap water cleaner, safer and better tasting.
Water running through an RO system typically first goes through a filter that removes sediment, then through a carbon filter before being forced through a tightly woven RO membrane. From there, the water may go through a series of optional specialty filters to reduce contaminants such as viruses, bacteria and more before arriving in the holding tank. Before the water comes out of the faucet, it’s run through one more advanced filter with more activated carbon for a final finish.
With all this science inside, it’s easy to see why RO systems are so powerful at solving a broad spectrum of water quality issues. In fact, high-capacity RO membranes can reduce up to 95% of undesirable substances in your water.
A great way to understand what specific water issues and contaminants a filtration system can address is to research third-party certifications. These certifications mean the system has been tested and verified by a third-party organization for the reduction of those substances.
For example, Culligan RO systems are certified to reduce up to 60 contaminants, including lead, chlorine, viruses, bacteria, lead, arsenic, volatile organic compounds (VOCs) and the toxic synthetic compounds called PFAS.
Filters in refrigerators and mounted on faucets may be third-party certified to reduce a high number of contaminants as well, depending on the filtration technology used. Those relying solely on carbon filtration have fewer capabilities.
Pitcher filters typically reduce the fewest number of impurities. Standard versions typically target issues with taste and odor, such as chlorine, which many municipal water systems use for disinfection and which can cause a bleach-like taste or smell.
If a product’s label doesn’t indicate which impurities it can reduce, you may find the answer in the database of the NSF, the main organization that develops drinking water system standards.
If you’re unclear about which, if any, contaminants are in your water, a local water expert can conduct an in-home water test. Alternatively, you can send a water sample to a certified lab.
In addition to thinking about what may need to be treated in your water, consider what system will be most convenient for you. Will you find it a bother to constantly refill a water pitcher? Also, will you replace the filters on schedule? While you may need to change a pitcher filter each month, you could go one to two years before changing an RO filter and five years before changing the RO membrane.
RO units are comprehensive, installed water treatment systems, so it’s probably not surprising that they have a higher upfront cost than the other options. Still, it’s worth factoring in their robust ability to reduce a broad spectrum of contaminants, their unmatched convenience and the peace of mind they offer those who prioritize the safety and taste of their drinking water.
*Contaminants may not be present in your water.