If you're serious about reducing contaminants in your drinking water, you've probably noticed that water filtration options run a wide spectrum of cost, complexity, and performance. A Brita pitcher costs $30 and needs filter replacements every month. A gravity-fed Berkey runs $300 upfront with much longer filter life. A reverse osmosis system installed under your sink can cost $400 to $800 and removes nearly everything, but uses more water in the process. So which one actually works, and which is right for your situation?
The answer depends on what contaminants you're most concerned about, your budget, and how much maintenance you're willing to do. This guide compares the three most common options based on what the research actually shows.
What you need to know about water contamination
Before choosing a filter, it helps to understand what might be in your tap water. Municipal water systems in the US are required to test for dozens of contaminants and stay below EPA action levels. That said, not all contaminants are equally regulated, and standards have been slow to catch up with emerging compounds.
In 2023, the US Geological Survey tested tap water samples from 716 locations across the country and found detectable levels of at least one PFAS compound (per- and polyfluoroalkyl substances, also called "forever chemicals") in samples from 45% of locations studied.1 PFAS don't break down in the environment or in your body, and research has linked some PFAS to health effects including increased cholesterol, decreased fertility, and altered immune response.2
Lead is another persistent concern, especially in homes built before 1986 when lead service lines were still legal. A 2024 study from Stanford and Johns Hopkins found that about 70% of children under 6 in Chicago have detectable lead in their tap water from aging infrastructure.3 Even low-level lead exposure in children is associated with decreased IQ and attention span.4
These findings don't mean your tap water is dangerous, but they do mean filtration is a reasonable choice for many households, particularly those with children or older lead service lines.
How activated carbon filters work (and what they don't remove)
Activated carbon has been used in water treatment for decades. The carbon is processed to be extremely porous, creating a large surface area that traps dissolved chemicals and odors. When water passes through a carbon filter, contaminants stick to the carbon through a process called adsorption.
Activated carbon is effective at removing chlorine, many pesticides, some volatile organic compounds (VOCs), and some PFAS compounds. The EPA notes that granular activated carbon (GAC) can be 100% effective at removing certain PFAS, but effectiveness depends on the carbon type, depth, flow rate, and the specific PFAS compound.5 Longer-chain PFAS like PFOA and PFOS adsorb well to carbon. Shorter-chain PFAS compounds do not, meaning no activated carbon filter removes all PFAS.
Where activated carbon falls short: it does not remove lead, nitrates, or fluoride through adsorption alone. Some higher-end carbon filters pair activated carbon with other media to address lead, but the base technology has limitations. Carbon filters also don't remove bacteria or viruses, though that's rarely an issue with municipal water.
The most common activated carbon products are pitcher filters like Brita and Pur. These are inexpensive to buy but expensive to maintain over time. A typical pitcher filter costs $30 to $50 upfront and $4 to $7 per replacement filter, with each filter lasting about 40 gallons. For a household using 40 gallons of filtered water per week, that's roughly 4 filters per year.
Gravity-fed filters: the Berkey and how they're tested
Gravity-fed filters like the Berkey work by dropping water down through layers of filtering media inside a gravity chamber. Water slowly percolates through the filters due to gravity alone, with no electricity or pressure required. This simplicity is both an advantage and a limitation.
Berkey filters use what the manufacturer calls Black Berkey Elements, which are made from proprietary media that the company says can remove over 200 contaminants. While Berkey systems are not NSF-certified (a process the company says would cost $320,000 to apply for all configurations), third-party testing has verified that the Black Berkey Elements perform to NSF/ANSI Standard 53 specifications.6 NSF 53 covers health-related contaminants including lead, certain pesticides, and some VOCs. However, Standard 53 does not test for PFAS removal.
This is an important caveat: if PFAS removal is your primary goal, Berkey's standard filters are not the right choice. The company sells upgraded filters for PFAS removal, but these are marketed separately.
On the cost side, a Big Berkey system costs roughly $300 to $350 upfront. Filter elements last about 6,000 gallons each, so for a household using 40 gallons per week, a set of two filters would last roughly 3 years. Over a 10-year period, a Berkey costs roughly $517 total when accounting for replacement filters, compared to $1,712 for Brita over the same timeframe.7
The downside of gravity filtration is speed. A Big Berkey produces about 1 gallon per hour. If you need large volumes of filtered water quickly, this is frustrating. You have to refill it regularly and plan ahead.
Reverse osmosis: highest removal but trade-offs
Reverse osmosis (RO) forces water through a semi-permeable membrane under pressure, removing 92-99% of dissolved solids, minerals, salts, and many contaminants. The membrane's pores are so small that most molecules cannot pass through. This is the most aggressive filtration method available for home use.
RO systems are highly effective at removing PFAS, lead, chlorine, fluoride, and nitrates. EPA testing shows RO can remove more than 99% of PFAS when equipped with appropriate pre-filters and post-filters.8 If you know your water has lead or PFAS and you want the highest confidence in removal, reverse osmosis is the right choice.
The main limitations are water waste and mineral depletion. A typical RO system produces about 1 gallon of filtered water for every 3 to 4 gallons that go down the drain. This is because the membrane rejects contaminants and sends them out as wastewater (called brine) to maintain the membrane's integrity. For every 5 gallons of drinking water, you might discard 12 to 15 gallons.
RO also removes minerals like calcium and magnesium, producing what's called demineralized water. The question of whether long-term consumption of mineral-free water causes problems is debated in the literature. Some studies from Eastern Europe reported health complaints including muscle weakness and cardiovascular symptoms in populations who switched to RO water systems, suggesting possible magnesium or calcium deficiency.9 However, the World Health Organization and other health authorities note that the majority of dietary minerals come from food, and in individuals with a balanced diet, electrolyte balance is maintained by the kidneys regardless of water mineral content.10
If you choose RO, you have two options. A point-of-use (POU) system installed under your kitchen sink filters only drinking and cooking water, typically costing $300 to $800. A whole-house RO system costs $2,000 to $5,000 or more. Most people use POU systems. Filter replacements are needed every 2 to 3 years and cost $80 to $200 annually, depending on water quality.
Comparing what each filter actually removes
Brita (activated carbon pitcher): Removes chlorine, taste and odor, some VOCs, some PFAS (longer-chain only). Does not remove lead, fluoride, nitrates, or bacteria.
Berkey (gravity-fed with standard filters): Removes lead, chlorine, some pesticides, some VOCs, and bacteria. Does not remove PFAS with standard filters; specialized PFAS filters available separately. Does not remove fluoride.
Reverse osmosis: Removes 92-99% of lead, PFAS, chlorine, fluoride, nitrates, most pesticides, minerals, and salts. Most comprehensive removal available. Requires regular membrane replacement.
NSF certification standards explained
You'll see NSF numbers thrown around in water filter marketing, so it helps to know what they mean. NSF International is a third-party certification organization that tests water treatment products against specific standards.
NSF/ANSI 42 covers taste and odor reduction (chlorine, sediment). This is what most pitcher filters claim.
NSF/ANSI 53 covers health-related contaminants (lead, certain pesticides, VOCs). This is what gravity-fed filters and some carbon systems test against.
NSF/ANSI 58 covers reverse osmosis systems and includes testing for lead, chlorine, and some other contaminants.
NSF/ANSI 401 covers emerging contaminants, including some (but not all) PFAS compounds.
A filter with NSF 53 certification tells you it has been independently tested and verified to remove certain contaminants to specific standards. A filter without NSF certification doesn't necessarily mean it doesn't work; it may mean the manufacturer chose not to pay for the certification process. When reviewing filters, check both whether they have certification and what specific contaminants they claim to remove.
Cost and maintenance comparison over time
The cheapest option upfront is Brita, but the cost adds up quickly. Here's a realistic 10-year cost estimate for a household using 40 gallons per week:
Brita pitcher: $30 initial system, roughly $144 per year in filters (12 filters yearly at $12 each), occasional replacement pitcher ($40 every 3 years). Total over 10 years: approximately $1,500 to $1,712.
Berkey: $325 initial system, roughly $100 per year in replacement filters (one pair every 3 years). Total over 10 years: approximately $517.
Reverse osmosis (point-of-use): $500 initial system, roughly $150 per year in filter/membrane replacements. Total over 10 years: approximately $2,000.
If your priority is minimizing long-term cost, Berkey wins by a substantial margin. If your priority is removing the widest range of contaminants including PFAS and lead, reverse osmosis is worth the cost. Brita is the least expensive entry point but becomes expensive to maintain.
Which filter should you choose?
Choose Brita or similar pitcher filters if: You're on a tight budget, you rent (and don't want to install anything), or you're filtering only drinking water in small quantities. Accept that you're mainly removing chlorine taste and odor, not addressing PFAS or lead. Plan to budget for regular filter replacements.
Choose a gravity-fed system like Berkey if: You want a good balance of cost and removal of common contaminants, you don't want to install anything, and you can tolerate waiting 1 to 2 hours for a gallon of filtered water to drip through. Make sure to buy the PFAS-specific filter media if PFAS is a concern in your area (check the USGS PFAS dashboard or ask your local water utility).
Choose reverse osmosis if: Your water has tested positive for lead or PFAS, you want the highest removal rates across the broadest range of contaminants, or you're willing to accept higher long-term cost and water waste for the most thorough filtration. Consider remineralizing the water if you use it as your primary drinking source, or simply ensure your diet includes adequate minerals from food.
Testing your water first
Before you buy anything, consider getting your water tested. Many local water utilities provide free or low-cost water quality reports (available online or by calling). If you have a private well, state health departments often offer affordable testing. A water test tells you what you're actually dealing with, which helps you choose the right filter instead of guessing.
If your water tests positive for lead or PFAS, reverse osmosis becomes more justified. If it's mainly chlorine taste and some sediment, a gravity-fed filter or pitcher is fine. Your actual situation matters more than marketing claims.
The bottom line
There is no single "best" water filter because the choice depends on what's in your water, your budget, and your tolerance for maintenance. Activated carbon (Brita) removes taste and odor effectively but isn't strong on PFAS or lead. Gravity-fed filters like Berkey offer better contaminant removal and much lower long-term cost but take time to produce filtered water. Reverse osmosis offers the broadest removal but uses more water and costs more to maintain. The USGS 2023 finding that nearly half of US tap water contains PFAS, combined with legacy lead contamination in many older homes, suggests that some filtration is worth considering for most households. Start with a water test if possible, then match your filter choice to what you actually need to remove. See our guide on best water filters for home for individual product recommendations and our article on PFAS-free cookware for other ways to reduce exposure.