When water is depleted, the system is vulnerable to chemical contamination.

Drinking water contamination can also come from the air and from damage to water system infrastructure. Heat can partially melt plastic pipes and water meters, releasing chemicals; smoke can be sucked into water systems; and breaks in the water infrastructure can introduce contamination.

A host of cancer-causing chemicals have been found in damaged water systems after wildfires. Sometimes these chemicals, such as benzene, can cause someone to become immediately ill if they drink or use the water. Symptoms can include nausea, headaches and rashes.

These chemicals stick to the infrastructure surfaces and can even penetrate some plastic pipes and gaskets. Removing them can take days to months. Some plastics can adsorb chemicals like a sponge and release them into clean drinking water slowly, making that water unsafe for long periods of time.