About 43 million Americans drink from private wells. None of them have a utility doing testing for them. That's the gap.
The Safe Drinking Water Act regulates public water systems. Private wells are explicitly excluded — by design, because Congress decided the federal government wouldn't reach into your home plumbing. Most state governments do the same. The CDC's bottom line: "the quality and safety of drinking water from private domestic wells are not regulated by the federal government nor by most state governments."
That makes well-water households responsible for two things city households aren't: annual testing for what's in the water, and treatment for what shouldn't be. This guide walks through both — what the CDC and EPA recommend testing, what the Pure XP pitcher and Smart Shield under-sink system actually filter, and where you'll still need a state-certified lab. Every removal percentage on this page is from independent third-party lab testing against the NSF/ANSI standard cited alongside it.
The short list
Four contaminants well-water households should filter for.
Public-health authorities focus on a handful of contaminants for private wells. Here's the short list, what each one is, why it matters specifically for well households, and the lab data on what Pure XP and Smart Shield actually filter.
Because no one is testing your water for you.
The CDC's #1 testing priority for private wells · Coliform & E. coli
Why it matters for well water
Bacterial contamination is the most common health risk for private wells, and the one the CDC names first when it tells households what to test for. Coliform bacteria are an indicator that surface water has reached the well — through a compromised casing, septic system, or runoff event. E. coli indicates fecal contamination specifically. The CDC recommends annual testing at minimum, and immediate testing after flooding, well repair, or any visible change in water clarity.
How it gets into your water
A USGS study of 2,100 private wells found that approximately 1 in 5 contained at least one contaminant at levels that could affect health. For wells, the contamination usually enters at the wellhead, through the casing, or via groundwater pulled through agricultural or septic systems. Boiling kills bacteria but doesn't help with chemical contaminants. Filtration handles both.
99.9999%
Smart Shield bacterial reduction. Six 9s — the microbiological gold standard. Tested against E. coli and total coliform.
Source: U.S. Geological Survey, "Domestic (Private) Supply Wells"; CDC Drinking Water — Guidelines for Testing Well Water.
Because pre-1986 plumbing is pre-1986 plumbing — well or city.
Heavy metal · The contaminant your well source isn't responsible for
Why it matters for well water
Lead almost never comes from your well or your aquifer. It comes from your home plumbing — brass fixtures, the solder in older copper pipe joints, and any service-line components your previous owners installed. Houses built before 1986 are most likely to have lead solder. The EPA and CDC agree there is no known safe level of lead exposure for children, and the AAP recommends keeping levels below 1 ppb. Since your well doesn't have a utility doing testing, the only way to know your water is lead-free at the tap is to filter at the tap.
How it gets into your water
Once water leaves your well and enters your home plumbing, it picks up whatever the plumbing materials shed. Older homes, brass faucets, soft (low-mineral) well water, and stagnant water in unused taps all elevate the risk. Boiling concentrates lead. Filtering removes it — if the filter is certified to NSF/ANSI Standard 53.
99.94%
Pure XP lead reduction. Independently lab-tested against NSF/ANSI Standard 53 — the EPA's recommended standard for lead. Smart Shield reduces lead by 99.4%.
Source: U.S. EPA Basic Information about Lead in Drinking Water; CDC Childhood Lead Poisoning Prevention; AAP Lead Exposure Policy.
Because rural wells aren't safer from PFAS — they're often worse.
Forever chemicals · A 2024 study found PFAS above health guidelines in 49% of rural wells sampled
Why it matters for well water
One of the most counterintuitive findings of recent research: private well water has PFAS contamination similar to or higher than public water systems. A 2024 study published in Environmental Science & Technology found PFAS above health guidelines in 49% of rural well samples across four U.S. states. The 2023 USGS estimate of 45% PFAS contamination across U.S. tap water counted private wells alongside public supplies and found similar rates. PFAS reaches groundwater through industrial discharge, firefighting-foam runoff, biosolids spread on agricultural land, and landfill leachate. The EPA finalized a federal PFAS limit of 4 ppt in 2024 — but that rule applies only to public water systems. Wells are unregulated.
How it gets into your water
Through groundwater. PFAS doesn't break down — that's literally the definition of "forever chemicals" — so once it reaches an aquifer, it persists. Private wells in agricultural and industrial regions, or near former military or firefighting-training sites, carry elevated risk.
99.8%
Pure XP PFAS reduction. Independently lab-tested against NSF/ANSI P473 (PFOA & PFOS). Smart Shield reduces PFAS by 96%.
Source: Environmental Science & Technology, "PFAS in Rural U.S. Well Water" (2024); USGS Environment International (2023); EPA PFAS NPDWR (April 2024).
Because plastic plumbing sheds, no matter what your source is.
Plastic fragments · The 2024 PNAS study found ~240,000 fragments per liter of bottled water
Why it matters for well water
Microplastics aren't a city-water-only problem. Plastic supply lines, polyethylene well casings, plastic pressure tanks, and plastic plumbing fittings all shed micro- and nanoplastic fragments into the water that flows through them. A 2024 Columbia and Rutgers study published in PNAS found bottled water averaged ~240,000 plastic fragments per liter — roughly 90% of which were nanoplastics small enough to cross into the bloodstream. The cleanest answer for any household, well or city, is to filter at the tap and skip the bottled water entirely.
How it gets into your water
Through plastic in the supply chain — packaging, plumbing, and degradation of plastic waste in surface and groundwater. For well households specifically, plastic well casings, pressure tanks, and PEX plumbing all contribute, even when the source aquifer is pristine.
99.6%
Pure XP and Smart Shield both reduce microplastics by 99.6%. Independently lab-tested against NSF/ANSI Standard 401 (Emerging Contaminants).
Source: Qian et al., "Rapid single-particle chemical imaging of nanoplastics by SRS microscopy," PNAS, January 2024.
Frequently asked questions
Is private well water regulated by the EPA?
No. The Safe Drinking Water Act regulates public water systems but explicitly excludes private wells. The CDC notes that the quality and safety of private well water is not regulated by the federal government nor by most state governments. Well-water households are responsible for their own testing, treatment, and ongoing monitoring.
How often should I test my well water?
The CDC recommends testing private well water at least once a year for total coliform bacteria, nitrates, total dissolved solids, and pH. Nitrate testing should be timed for April through July, when levels are typically highest in agricultural areas. Test more frequently after flooding, after well repair work, or if anyone in the household is pregnant, nursing, or under one year old.
What's the biggest contamination risk for well water?
Bacterial contamination is the most common health risk for private wells — coliform bacteria and E. coli enter through compromised well casings, surface runoff, or septic systems. The CDC ranks it as the #1 testing priority. A USGS study found that approximately 1 in 5 private wells contain at least one contaminant at levels affecting health.
Can I mix well water with infant formula?
Only if the well water has been tested and confirmed safe. The EPA specifically warns that well water containing more than 10 mg/L of nitrate should NOT be used to mix infant formula, as it can cause methemoglobinemia (blue baby syndrome). If you have not tested your well, or if results are uncertain, the EPA recommends using bottled water or water from a tested public supply for formula prep.
Do I really need both Pure XP and Smart Shield for well water?
Layered protection is the most reliable approach. Smart Shield + Sediment Filter installs under your kitchen sink and provides 99.9999% bacterial reduction, sediment filtration, and ~12 months of filter life — addressing the full water flow you cook and drink with. Pure XP adds a portable, additional layer for drinking water, with NSF certification to Standard 42 and independent testing against NSF/ANSI 53, 401, P231, and P473. Many well-water households use both for complete coverage.
Does Smart Shield remove arsenic or nitrates?
Smart Shield is NSF/ANSI certified to Standards 42, 53, and 401 by IAPMO, with tested removal data for bacteria, lead, PFAS, microplastics, glyphosate, uranium, VOCs, and disinfection byproducts. It is not specifically certified for arsenic or nitrate reduction, which typically require NSF/ANSI Standard 58 reverse osmosis systems. If your well is in a high-arsenic region (the U.S. West and parts of New England) or near agricultural land, get a comprehensive well-water test from a state-certified lab and consider RO filtration in addition to your Smart Shield.
How long does the Smart Shield filter last on well water?
Up to 651 gallons or 12+ months in most households. On well water with significant sediment, the included sediment pre-filter takes the brunt of particle loading, which extends the life of the main filter. Sediment filters are inexpensive and easy to swap as needed.
Where are these filters made?
Pure XP is manufactured in our own facility in Palmetto, Florida. Smart Shield is made in North America. Epic is vertically integrated — manufacturing, quality control, and assembly happen in-house, with filtration media sourced from the U.S. and Japan.
