While the United States has one of the safest public drinking supplies in the world, according to the Centers for Disease Control and Prevention, water can contain many types of contaminants, from minerals to pesticides to fertilizers. The Water Quality Association (WQA) states that you can’t necessarily see, smell, or taste all the microbial and organic contaminants in tap water. So, for health and environmental reasons, some people choose to filter their tap water.

Some water filters remove lead, some remove pesticides, and others simply neutralize the bad taste and odor of chlorine. Water filtration systems also come in a variety of forms, from pitchers to faucet-mounted filters to plumbed-in systems that sit under your kitchen sink. With so many water filters on the market, which one should you choose to optimize your health?

Ecologist James McMahon points out that your first step should be to get a copy of your local water quality report. “That will identify the source of the water and the regulated contaminants. Armed with this information, buy the filter that removes those contaminants,” says McMahon. If you’re looking for a more general, all-purpose water filter, take a look at these seven water filtration systems, certified by the National Sanitation Foundation (NSF) to make your tap water cleaner.

1. PUR

PUR sells water filter pitchers, dispensers, and faucet mounts. The PUR Ultimate Horizontal Faucet Water Filter ($49.99 upfront, but you’ll also have to pay for replacement filters) removes more than 70 contaminants. Each filter lasts for 100 gallons of water (which the typical household uses in three months) and reduces lead by 99 percent, mercury by 96 percent, and pesticides by 92 percent.

Experts debate the merits of PUR versus Brita, two similarly priced water filter products, but the general consensus seems to be that PUR has a slight edge over Brita in terms of efficiency, design, and convenience. And testing done by the University of Arizona’s Laboratory for Emerging Contaminants showed that the PUR CR-6000 pitcher ($15) outperformed Brita and removed a variety of pollutants from tap water, including the herbicide atrazine and pesticide DEET.

2. MAVEA

Mavea sells water filter pitchers as well as a filtration system that fits under your sink. Mavea’s Maxtra filters are certified by the Water Quality Association to reduce chlorine (which can make tap water smell and taste bad), heavy metals such as mercury and copper, pesticides, and chemicals such as benzene.

Mavea’s filters use activated charcoal and ion exchange resin beads to remove pollutants, and they also claim to filter limescale out of hard tap water (this has not been verified by the WQA). All of Mavea’s plastic parts are BPA-free, and the products are designed and made in Germany.

3. ISPRING WATER SYSTEMS

The iSpring RCC7 ($195) uses a five-stage reverse osmosis process to filter water. Situated under the sink, the iSpring filters out over 1000 pollutants including pesticides, pharmaceutical residues, chlorine, lead, copper, and arsenic. Awarded a Gold Seal from the Water Quality Association, the iSpring uses carbon filters, a sediment filter, and a reverse osmosis membrane.

According to Consumer Reports, reverse osmosis water filters do a good job of removing contaminants from tap water, but they can take up a lot of space and usually waste water (filtering one gallon of water can create three to five gallons of excess water that is wasted). Besides filtering out the bad stuff, reverse osmosis filters also remove good, naturally occurring minerals in tap water. And if you’re renting an apartment, keep in mind that installing reverse osmosis filters under your sink may require making minor plumbing modifications, which you might not be allowed to do depending on your lease agreement.

4. CULLIGAN

Culligan offers whole house water filter systems, which filter water from all the faucets in your home, as well as filters that fit directly on your sink or shower head. Culligan’s AC-30 Good Water Machine, for example, fits under your sink and uses three filters to reduce sediment, filter out chlorine taste and smell, and reduce barium and radium via reverse osmosis.

Jennifer Goodwin, the founder and CEO of Higher Health, uses a Culligan reverse osmosis system installed in her kitchen sink. “If people want to optimize their brain function, have a healthy liver, be able to age well, and have energy, then they really have to pay attention to their environment—it’s non-negotiable,” says Goodwin.

She also recommends filtering any water that comes into regular contact with your skin—not just the water you ingest. “Anytime you wash vegetables and fruits, brush your teeth, and take a shower or bath, you should be using filtered water,” says Goodwin.

5. RADIANT LIFE

If you’re willing and able to shell out big bucks for a water filtration system, consider Radiant Life. Katie of Wellness Mama recommends Radiant Life’s 14-Stage Biocompatible Water Purification System, which ranges in price from $1595 to $1695 depending on the size tank you choose.

The 14-stage system, which you install under your sink, purportedly removes 99 percent of toxins such as lead, pharmaceutical residues, nitrates, pesticides, and chlorine. The purifiers use reverse osmosis, carbon filtering, deionization, ultraviolet light, and alkalizing, and one of the final steps in the process adds back natural minerals that were removed during the reverse osmosis stage.

6. MULTIPURE

Multipure makes water filters, such as Aquadome, Aquamini, and Aquaperform, that greatly reduce contaminants such as lead, mercury, asbestos, chlorine, volatile organic compounds, and polychlorinated biphenyls. Multipure’s filters use solid carbon blocks, mechanical filtration, and electrokinetic adsorption to remove contaminates.

For $372.95, you can purchase Multipure’s MP750SI Drinking Water Filter for Inline. This filter doesn’t attach directly to your kitchen faucet (it requires a separate faucet), so if you’re short on kitchen space, consider the Countertop Kit instead.

7. BERKEY

Berkey offers a line of water filters for home, travel, and sports use. By means of microfiltration, adsorption, and ion exchange, Berkey’s filters ($258) remove almost 100 percent of pathogenic bacteria and viruses from tap water, and they greatly reduce the amount of volatile organic compounds and metals such as aluminum, copper, lead, mercury, and nickel.

Briana Ryan, a wellness coach and plant-based chef based in Los Angeles, says she loves her Berkey water filter. “As a chef and wellness coach, having pure water without contaminants, including fluoride, is incredibly important to me. I use an enormous amount of water for cooking and my Berkey water purification system has been one of the best investments I've made,” says Ryan.