Is it safe to store drinking water in polyethylene terephthalate (PET) bottles stored in warm kitchen cupboards?
No. Storing water in PET bottles at warmer temperatures increases the migration of harmful chemicals into your water, according to a 2026 study in the Journal of Food Science and Technology.
What's actually in it
Polyethylene terephthalate (PET) bottles are not as stable as they seem. When these plastic containers are exposed to heat, they release phthalates: a class of chemicals used to make plastics flexible and durable. These compounds are not meant to be consumed, yet they move from the plastic walls of the bottle directly into your drinking water.
What the research says
A 2026 study in the Journal of Food Science and Technology examined how temperature changes affect the safety of PET bottles. The researchers found that as the temperature rises, the amount of phthalates leaching into the water increases significantly. Storing these bottles in a warm kitchen cupboard creates an environment that accelerates this chemical transfer.
This peer-reviewed research highlights that the longer your water sits in a warm environment, the more you are exposed to these substances. Because these chemicals can migrate into your drink, keeping plastic water bottles in warm storage areas is not a safe practice for your household.
The research at a glance
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