💧Water Quality
Tap water across most developed countries contains measurable levels of pharmaceuticals, heavy metals, microplastics, chlorine byproducts, and PFAS chemicals. Understanding what is in your water and how to filter it is a meaningful health intervention.
Tap water in most developed countries meets regulatory safety standards — but those standards lag significantly behind the research on emerging contaminants. The Environmental Working Group (EWG) maintains a database of over 300 contaminants detected in US tap water, many of which have no regulatory limits despite evidence of harm at detected concentrations.
The most concerning categories of water contaminants are PFAS (per- and polyfluoroalkyl substances — "forever chemicals"), heavy metals (particularly lead from aging pipe infrastructure), disinfection byproducts (trihalomethanes and haloacetic acids formed when chlorine reacts with organic matter), microplastics, and pharmaceutical residues including hormones and antibiotics.
The good news: effective water filtration exists. Reverse osmosis (RO) systems remove over 99% of most contaminants including PFAS, heavy metals, nitrates, and pharmaceuticals. Activated carbon filters (like Brita) remove chlorine, some pesticides, and improve taste but do not remove PFAS, heavy metals, or nitrates. Understanding what you are filtering for determines what filter you need.
The Science
Health Benefits
- Reverse osmosis removes 95-99% of PFAS, lead, nitrates, arsenic, fluoride, and most pharmaceuticals
- Activated carbon filters (pitcher, faucet, under-sink) remove chlorine, chloramines, some pesticides, and improve taste but leave PFAS and heavy metals
- Whole-house filters protect skin and lungs from chlorine during showering — relevant since shower inhalation and skin absorption can exceed drinking water exposure
The mechanism: Reverse osmosis works by forcing water through a semi-permeable membrane with pore sizes of 0.0001 microns — small enough to remove virtually all dissolved contaminants. The tradeoff is that RO also removes beneficial minerals (calcium, magnesium) — remineralization cartridges or mineral supplementation addresses this. RO systems produce wastewater (typically 3-4 gallons per gallon of filtered water) but under-sink tankless versions have improved significantly.
- PFAS are found in 45% of US tap water samples — significantly higher near military bases, airports, and industrial facilities
- PFAS accumulate in the body over time — reducing exposure meaningfully requires sustained filtration
- Even short-term PFAS reduction measurably reduces blood PFAS levels in studies of filtered water interventions
The mechanism: PFAS (per- and polyfluoroalkyl substances) are called forever chemicals because they do not degrade in the environment or body. They accumulate in blood and organs over decades of exposure. PFAS are associated with thyroid cancer, kidney cancer, ulcerative colitis, thyroid disease, high cholesterol, and immune suppression. Granular activated carbon and reverse osmosis both effectively remove PFAS from drinking water.
- Lead from aging pipes and fixtures remains a significant risk — particularly in homes built before 1986 and cities with older infrastructure
- Arsenic exceeds EPA limits in well water in many agricultural areas — associated with bladder, lung, and skin cancer
- Running cold tap water for 30 seconds before use reduces lead exposure significantly when filters are not available
The mechanism: Lead enters drinking water primarily through corrosion of lead pipes, lead solder, and lead-containing brass fixtures — not from water treatment or source water. The lead in Flint, Michigan was caused by water chemistry changes that made the water more corrosive. Older homes (pre-1986) and cities with aging infrastructure have the highest risk. Water testing is the only way to know if lead is present — visual inspection of pipes is insufficient.
How to Do It
How to Track Progress
Recommended Products & Supplements
Safety & Considerations
- Well water users should test annually — wells are not subject to EPA regulations and can contain bacteria, nitrates, arsenic, radon, and other contaminants at high levels.
- RO systems remove fluoride along with other contaminants — those in areas with suboptimal fluoride levels should discuss dental implications with their dentist.
- Do not rely on Brita-style pitcher filters for PFAS, heavy metal, or nitrate removal — they are only rated for chlorine, some pesticides, and taste improvement.
This guide is for informational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making changes to your health routine.
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