Bottled water is sold with imagery of mountains, springs and purity. It is the most expensive way to buy water per litre in human history. It is also less regulated than tap water in most developed countries, frequently contains microplastics shed from the bottle itself, and in some cases contains PFAS, pharmaceuticals and other contaminants at levels exceeding those in municipal tap water. The scientific evidence consistently supports filtered tap water as the better choice by nearly every measure.
The regulatory gap between tap and bottled
In the United States, municipal tap water is regulated by the EPA under the Safe Drinking Water Act. Water utilities must test for over 90 contaminants, test multiple times per day for some, make results publicly available in an annual Consumer Confidence Report, and notify consumers within 24 hours of any violation. Bottled water is regulated by the FDA as a packaged food product. The FDA requires annual testing (compared to multiple times daily for tap), does not require companies to share testing results publicly, and does not require notification of consumers if a violation is found.
Microplastics in bottled water
A landmark 2018 study in Frontiers in Chemistry tested 259 bottled water products from 11 global brands across 9 countries and found microplastic contamination in 93% of samples, at an average of 325 particles per litre. The most common plastic found was polypropylene, consistent with the bottle caps. The particles primarily originate from the bottle and the bottling process itself, not from the source water. Sparkling water in plastic bottles contains higher particle counts than still water, likely due to carbonation pressure affecting the bottle interior. A 2023 study in Nature Water found nanoplastic concentrations in bottled water approximately 100 times higher than previously estimated using new measurement techniques.
PFAS in bottled water
Independent testing by the Environmental Working Group and Consumer Reports found PFAS in several major bottled water brands, including some marketed as natural spring water. PFAS can enter natural spring sources from industrial contamination, agricultural runoff and military base leaching into groundwater. In 2020, Consumer Reports tested 47 bottled waters and found PFAS in several at levels exceeding proposed EPA limits. Source purity claims on bottled water labels do not guarantee PFAS absence.
The cost comparison
Tap water in the US costs approximately 0.004 dollars per litre on average. Bottled water costs 1 to 3 dollars per litre, making it 250 to 750 times more expensive. A Clearly Filtered water pitcher at approximately 85 dollars removes 365 or more contaminants including PFAS, lead, chlorine byproducts and microplastics. At two litres per day of filtered tap water, the per-litre cost including filter replacement is approximately 0.02 dollars, 50 to 150 times cheaper than bottled water. An under-sink reverse osmosis system at approximately 200 dollars brings the per-litre cost to approximately 0.01 dollars over its lifetime.
What to do
Check your tap water quality report
In the US, your municipality's Consumer Confidence Report is publicly available and shows what was detected and at what levels. Search for your water utility name plus water quality report. EWG also maintains a national tap water database at ewg.org/tapwater.
Install a pitcher or under-sink filter
For PFAS removal, you need a Clearly Filtered pitcher, a ZeroWater pitcher, or a reverse osmosis system. Standard Brita filters do not remove PFAS. For lead and chlorine only, a standard carbon filter is sufficient.
Switch to a stainless steel water bottle
Carrying filtered tap water in a stainless steel bottle eliminates bottled water costs and microplastic exposure simultaneously. Klean Kanteen or Hydro Flask are the benchmark options.