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Water BODY HANDBOOK
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Tap Water Contaminants
Your tap meets federal limits. That is not the same as clean: the limits track what utilities could afford to remove, and the EPA's health goal for lead and PFOA is zero EPA 2024. Half of US taps carry PFAS "forever chemicals," lead leaches from millions of old pipes, and chlorine's byproducts trail two decades of bladder-cancer signal. None of it makes you feel anything, which is why it goes untreated. A $30 pitcher on the right standard removes most of it.
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Three families do the chronic-disease work. PFAS are built on the strongest bond in organic chemistry, so they neither break down nor leave the body cleanly, and sit in your blood for two to five years 1. Lead comes off old pipes and solder, then substitutes for calcium in bone and brain, with no safe dose. Disinfection byproducts form when chlorine hits organic matter after the water leaves the plant; you take them in by drinking and by breathing hot-shower steam.

Three bodies of human data, three diseases. PFOA carries a probable link to kidney cancer, testicular cancer, and thyroid disease; the kidney-cancer risk runs about a third higher at high exposure 2, and it halves a child's antibody response to a vaccine 3. Lead's harm has no floor: the IQ cost per unit is larger at low doses than high 4, and blood lead tracks cardiovascular death down to trace levels 5. Byproducts roughly double bladder-cancer risk at high exposure 6.

The filter aisle is where people go wrong: they buy on price, and a $20 pitcher and a $40 one look identical. The certification number on the box separates them.

Week one buys clarity, not health. The chlorine taste drops out of the glass. The real return is slow and invisible.

  • First year: your blood PFOS and PFOA start falling the day the inflow stops, on a two-to-five-year half-life 1. Lead body burden follows, more slowly.
  • Over a decade: your intake of all three families drops 80โ€“99%, and your attributable risk shrinks with it.
  • With a child in the house the payoff lands sooner: filtering closes one of the two main childhood lead routes while the brain is scaling 4.

Different question, different entry: well water is unregulated and needs its own testing; fluoride is added on purpose and is its own debate; microplastics are detectable but not yet tied to human harm.

The fine print โ€” when to skip it, and what people get wrong

Bottled isn't cleaner: a quarter is municipal tap, it carries its own PFAS and microplastics, and costs a thousand times more. Boiling kills bacteria but concentrates lead, PFAS, and byproducts. "Compliant" is the floor, not the ceiling 8.

References
  1. 1ATSDR (2021). Toxicological Profile for Perfluoroalkyls. link
  2. 2Barry V, Winquist A, Steenland K (2013). Perfluorooctanoic acid (PFOA) exposures and incident cancers among adults living near a chemical plant. Environmental Health Perspectives. link
  3. 3Grandjean P, et al. (2012). Serum vaccine antibody concentrations in children exposed to perfluorinated compounds. JAMA. link
  4. 4Lanphear BP, et al. (2005). Low-level environmental lead exposure and children's intellectual function: an international pooled analysis. Environmental Health Perspectives. link
  5. 5Lanphear BP, Rauch S, Auinger P, Allen RW, Hornung RW (2018). Low-level lead exposure and mortality in US adults: a population-based cohort study. The Lancet Public Health. link
  6. 6Villanueva CM, et al. (2007). Bladder cancer and exposure to water disinfection by-products through ingestion, bathing, showering, and swimming in pools. American Journal of Epidemiology. link
  7. 7EWG (2021). EWG's Tap Water Database. link
  8. 8EPA (2024). PFAS National Primary Drinking Water Regulation. link
Related in the handbook (11)
Related
  • โ€” Tap water can carry Acanthamoeba; that's why rinsing or storing contact lenses in it risks a sight-threatening eye infection.
  • โ€” If your tap water isn't reliably safe, storing it in copper overnight kills many of the bacteria.
  • โ€” Tap water is fine to drink but not to pour up your nose; a rare amoeba makes saline rinses one place tap water can actually kill you.
  • โ€” PFAS show up in some tap water as well as non-stick pans; both are worth checking when you're reducing forever-chemical exposure.
  • โ€” If you drink a couple of litres a day, what is in that tap water matters. Check for lead, PFAS, and disinfection byproducts.
  • โ€” Same defensive move as buying organic for the high-spray dozen โ€” clean up the inputs you can, skip the panic.
  • โ€” Switching to bottled water to avoid tap contaminants just swaps in microplastics; filter the tap instead.
  • โ€” The chlorine a shower filter targets is the same disinfection chemistry behind tap-water worries โ€” just inhaled instead of drunk.
  • โ€” Fluoride is added on purpose, unlike the contaminants here โ€” but both are reasons to actually know what your tap carries.
  • โ€” Pick the filter by matching it to whatever your utility report says is actually in the water.
  • โ€” The reverse-osmosis filter that strips PFAS and lead also strips beneficial minerals โ€” which is why remineralizing follows.
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