No single bottled water brand is universally “the safest,” but purified water that has gone through reverse osmosis consistently tests lowest for contaminants across independent lab analyses. The more important factors are the type of water (purified vs. spring), how it’s stored, and what container it comes in. Understanding these variables gives you more control over water safety than chasing a specific brand name.
How Bottled Water Is Regulated
The FDA oversees bottled water safety in the United States, using standards that mirror what the EPA sets for public tap water. Every time the EPA establishes a new contaminant limit, the FDA either adopts it for bottled water or explains why it isn’t necessary. In some cases, bottled water actually has stricter limits. Lead in tap water is allowed up to 15 parts per billion because it can leach from aging pipes between the utility and your faucet. Bottled water, which never touches lead pipes, has a limit of 5 ppb.
These standards cover bacteria, heavy metals, and chemical contaminants. But regulation sets a floor, not a ceiling. Two brands can both meet FDA requirements while having very different purity profiles, which is why independent testing matters.
Purified Water vs. Spring Water
The label on a bottle tells you a lot about what’s inside. “Purified water” can come from any source, including municipal tap water, but it must go through processes like reverse osmosis, distillation, or deionization that strip out nearly all dissolved solids, chemicals, and microorganisms. The tradeoff is that purification also removes naturally occurring minerals like calcium and magnesium.
Spring water comes from an underground source and flows naturally to the surface. It’s filtered before bottling to remove visible impurities and harmful contaminants, but the treatment is gentler by design. It retains its mineral content, which some people prefer for taste. That lighter filtration, however, means spring water is more likely to carry trace levels of environmental contaminants that seeped into the groundwater.
If your priority is minimizing contaminant exposure, purified water processed through reverse osmosis is the more reliable choice. If you want minerals and prefer the taste of spring water, look for brands that publish third-party test results.
What Independent Testing Has Found
Consumer Reports tested dozens of bottled water brands for PFAS (synthetic “forever chemicals”), heavy metals, and other contaminants. Most noncarbonated products had detectable levels of PFAS, but only two brands, Tourmaline Spring and Deer Park, exceeded 1 part per trillion. Heavy metals were well below federal limits across the board, with one notable exception: Starkey Spring Water, owned by Whole Foods, which had elevated arsenic levels.
The FDA conducted its own testing of 197 bottled water samples spanning purified, artesian, spring, and mineral waters. Ten samples had detectable PFAS levels, but none exceeded the EPA’s maximum contaminant levels. The detectable samples were a mix of domestic purified and spring waters, plus two imported artesian waters. Earlier FDA surveys in 2016 found no detectable PFAS in bottled water at all, suggesting that testing sensitivity has improved and that trace contamination may be more widespread than previously understood.
For context, the EPA finalized enforceable limits for two of the most common PFAS chemicals (PFOA and PFOS) at 4 parts per trillion in 2024, with a health goal of zero. That 4 ppt threshold is extremely low, which tells you how seriously regulators view even tiny exposures.
The Microplastics Problem
A study highlighted by the National Institutes of Health found that a liter of bottled water contains roughly 240,000 tiny plastic particles on average. About 90% of those were nanoplastics, fragments so small they can potentially cross cell membranes. That number is 10 to 100 times higher than earlier estimates, which had focused only on larger microplastic pieces.
The plastic comes primarily from the bottle itself. PET (the plastic most water bottles are made from) sheds particles over time, and the process accelerates with heat and prolonged storage. Research on sunlight exposure found that storing bottled water in direct sunlight increased microplastic contamination by about 2.5%, compared to 1.5% for bottles stored in the dark. Both increased over time regardless of light conditions.
If microplastics concern you, glass-bottled water eliminates the container as a source. Brands like Mountain Valley Spring Water and some European mineral waters (Gerolsteiner, San Pellegrino in larger formats) are available in glass. You can also fill your own glass or stainless steel bottle with filtered tap water.
How Storage Affects Safety
A sealed bottle of water doesn’t spoil in the traditional sense, but its container slowly degrades into the water. Temperature is the biggest accelerator. At room temperature (around 72°F), antimony leaching from PET plastic stays minimal for months. But at 158°F, the kind of heat a bottle reaches sitting in a hot car on a summer day, antimony concentrations jumped to 6 ppb in just 12 days in one study. At 176°F, it took only 2.3 days to reach that level, and after a week the concentration hit 14.4 ppb.
Phthalates, another class of chemicals used in plastic manufacturing, follow a similar pattern. At 77°F, detectable levels appeared after about 25 days. At 113°F, concentrations nearly doubled over the same period. Even at room temperature, one study found that chemical compounds extracted from PET bottles increased significantly after nine to ten months of storage.
The practical takeaway: store bottled water in a cool, dark place, and don’t drink from bottles that have been sitting in a hot car or in direct sunlight for extended periods. Use water relatively soon after purchasing it rather than stockpiling it for months.
What to Look for When Choosing a Brand
Rather than memorizing a single “safest” brand, focus on a few reliable indicators:
- Look for “purified” on the label. Reverse osmosis or distillation removes the widest range of contaminants, including PFAS, heavy metals, and dissolved chemicals. Brands like Aquafina (Pepsi) and Dasani (Coca-Cola) use reverse osmosis on municipal water. Smartwater uses vapor distillation.
- Check for third-party testing. Some brands publish independent lab results on their websites. Transparency about what’s in the water is a strong signal that the company takes purity seriously.
- Consider the container. Glass bottles eliminate plastic leaching and microplastic shedding entirely. If you buy plastic, avoid bottles that have been exposed to heat.
- Be cautious with “natural” or “raw” water. Marketing that emphasizes an untreated, natural source sounds appealing but means less filtration and greater potential for contaminants.
How Bottled Water Compares to Filtered Tap
In most of the United States, tap water meets or exceeds the safety of bottled water. Municipal water systems test far more frequently than bottled water producers and must report results publicly. A quality home filter, whether a pitcher-style carbon filter for chlorine and taste or a countertop reverse osmosis system for heavy metals and PFAS, can bring tap water to the same purity level as premium bottled water at a fraction of the cost.
Bottled water makes sense for emergencies, travel, or areas with compromised municipal systems. But for everyday drinking at home, a good filter paired with a reusable glass or steel bottle sidesteps both the contaminant concerns and the microplastic issue that come with single-use plastic bottles.