Water Filtration near you

The format decides how much water gets treated and how often someone has to do something about it. EPA's own ordering runs roughly from least to most costly, and it is a useful way to think about the choice.

Filter packaging is full of words that mean nothing and a few marks that mean a great deal. EPA groups the standards by what they cover: NSF/ANSI 42 is Drinking Water Treatment Units, Aesthetic Effects, dealing with things like taste and odor; NSF/ANSI 53 is Health Effects; and NSF/ANSI 401 covers emerging compounds and incidental contaminants. EPA's older consumer guidance explains the underlying structure: each standard requires verification of contaminant reduction performance claims, an evaluation of the unit including its materials and structural integrity, and a review of product labels and sales literature.

Lead is the case where the detail has been spelled out for consumers. EPA's tool for identifying point-of-use and pitcher filters certified to reduce lead advises buying filters evaluated by an accredited third-party certification body for drinking water lead reduction to 5 parts per billion or less and for particulate reduction at Class I, and explains what to look for: the certification body's mark together with a statement indicating testing against NSF/ANSI Standard 53 and a claim of lead reduction. The mark may be on the packaging, on the filter itself, or on the smallest container the filter is packaged in, and the specific claims live on the performance data sheet.

Several bodies do this work and each has its own registered mark. EPA names NSF, the Water Quality Association, UL Solutions, CSA Group and IAPMO R and T among the ANSI-accredited certification bodies whose product directories you can search by model. CDC's version of the same advice is one sentence long: look for an NSF certification on the filter's label, and look the product up in the database to see what it is certified to remove. If a product carries no mark at all, EPA's older guidance is to contact the manufacturer directly and ask for proof of its claims.

Filter holes are measured in microns, and EPA offers a memorable reference point: the period at the end of a printed sentence is about 500 microns. Against that, EPA lists Giardia lamblia at 8 to 12 microns, Cryptosporidium parvum at 4 to 6 microns, bacteria such as E. coli and salmonella at 0.2 to 4 microns, and viruses at 0.004 to 0.1 microns, noting that generally only a few filters, such as ultrafilters and reverse osmosis, have holes small enough to assure removal of all viruses, though viruses can be killed with a disinfectant.

CDC describes the same ladder by process: microfiltration at around 0.1 micron pores, ultrafiltration at 0.01, nanofiltration at 0.001 and reverse osmosis at 0.0001. It also makes the point that most home water filters, such as pitcher or refrigerator filters, are not designed to remove germs from water, which is a common and dangerous misunderstanding among people on private wells.

For Cryptosporidium specifically, both agencies converge on a single instruction that is worth writing down. EPA and CDC recommend an absolute one micron filter, or one labeled for cyst removal, and EPA's guidance for immunocompromised households is that filters using reverse osmosis, those labeled as absolute one micron, or those certified by an ANSI-accredited organization to NSF/ANSI Standard 53 for cyst removal provide the greatest assurance. That is the level of specificity that actually protects somebody, and it is why an absolute rating rather than a nominal one matters.

PFAS is the contaminant most Americans have started asking about, and EPA's fact sheet on home filters for it is unusually candid. It advises first contacting your water provider to find out which PFAS, if any, are in your drinking water, and notes that if PFAS have not been measured in your water, or have been measured but are below federal limits, a filter may not be useful to you. Where a filter is warranted, EPA names three technologies that can be effective: granular activated carbon, reverse osmosis, and ion exchange resins.

The certification instruction is specific. EPA says to check the product packaging for certification to NSF/ANSI 53 or NSF/ANSI 58 for PFAS reduction, and if in doubt to check the certification body's product directory or contact the body directly. It then adds a caveat that no marketing will mention: as of April 2024, filter certification standards focus on PFOA and PFOS, and those certifications do not yet indicate that a filter will remove PFAS down to the levels EPA has set as a drinking water standard, with EPA working with standard-setting bodies to update them. Reducing PFAS is still an effective way to limit exposure, but a certified filter is not the same as a guaranteed compliance result.

Lead has its own trap. Boiling does not help, and EPA is explicit that boiling water does not remove lead. Nor does every carbon filter: EPA's list of technologies for removing specific contaminants names distillation, reverse osmosis and some carbon filters for lead, which is why the NSF/ANSI 53 lead claim, verified on the performance data sheet, is the thing to look for rather than the word filter.

A point-of-use filter treats water at a tap, and EPA notes that for most contaminants a point-of-use device is effective for treating only the water that is consumed. For a household whose concern is lead from its own plumbing, or taste, or a specific health-effects contaminant in drinking water, that is usually the efficient answer, and it keeps the cost of cartridges proportional to the water actually drunk.

Whole-house treatment also opens up equipment that does not fit under a sink at all, and EPA describes two kinds. Adsorptive media work by having liquids, solids and dissolved or suspended matter adhere to the surface of, or in the pores of, a solid material, which is the principle carbon filters use. Aerators force water to travel over air jets, removing contaminants that easily turn into gases such as gasoline components and radon, while leaving other contaminants untouched, so water is often filtered again afterward. EPA's own contaminant list pairs radon with activated carbon filtration and aeration, and arsenic with adsorptive media, which is a reminder that the right answer is chosen by contaminant rather than by cartridge.

One piece of labeling confuses almost everybody, and it is worth clearing up before you shop. Some filters carry an EPA registration number, and EPA states plainly that this registration is not intended to guide consumers in selecting a water treatment device and is not an endorsement of the product. EPA registers products containing an antimicrobial or bacteriostatic agent, most commonly silver, used to slow the growth of microbes inside the filter itself. It is a pesticide registration, not a performance claim, and it says nothing about what the filter removes from your water.

The number that matters on a filtration system is rarely the installation. The variables are which contaminants are being targeted and therefore which standards the unit must be certified to, whether it is a point-of-use device at one tap or a point-of-entry unit at the service, the flow rate the household needs and how that sets the housing size, whether a dedicated faucet or a refrigerator line is being added, how much plumbing has to be modified, whether a pre-filter is needed to protect the main cartridge on a sediment-heavy supply, and, dominating the long run, the price and interval of replacement cartridges. Ask for the annual cartridge cost in writing next to the installation figure, because that is where two systems that look equivalent stop being equivalent.

LokalMatch is the introduction and no more than that. Describe your water and which taps you want treated, and the filtration and plumbing companies covering your ZIP code decide whether to respond; the interested ones contact you directly and pay for the request. There is no charge to the homeowner. LokalMatch does not sell filters, does not test water, takes no part in pricing and does not vet, rank or recommend anyone, so confirming the certification, the specific contaminant claims on the performance data sheet and the maintenance terms remains your responsibility.