Can plastic food containers make tap water disinfection byproducts more toxic?

What's actually in it

Tap water is treated with chlorine or chloramine to kill bacteria. That treatment creates disinfection byproducts (DBPs) like trihalomethanes and haloacetic acids. These byproducts are present at low levels in most tap water and are generally considered a small risk on their own.

Plastic food containers, meanwhile, release micro- and nanoplastics into whatever liquid they hold. When you store tap water in a plastic pitcher or container, the DBPs in the water meet the plastic particles from the container.

What the research says

A 2025 study in Food Chem tested what happens when micro- and nanoplastics from plastic containers combine with disinfection byproducts. The researchers exposed human cells to DBPs alone, plastic particles alone, and the combination of both.

The combination was highly more toxic than either one alone. Cells exposed to both DBPs and plastic particles showed more DNA damage, more oxidative stress, and lower survival rates. The plastic particles appeared to act as carriers, concentrating the DBPs on their surface and delivering a bigger dose directly to cells.

This "cocktail effect" is something regulators don't typically account for. Safety limits for DBPs in tap water assume the chemicals act alone. They don't consider that storing water in plastic might make those same chemicals more dangerous.

Storing tap water in glass or stainless steel containers avoids adding microplastics to the mix. If you use a plastic water pitcher, replace it regularly and don't let water sit in it for days. A simple activated carbon filter can also reduce DBP levels before the water touches plastic.