For uses such as in shampoos, conditioners and detergents, which naturally enter wastewater, the aquatic compartment is of key importance. However volatile methylsiloxanes (VMS) are rapidly lost into the air and polydimethylsiloxanes (PDMS) do not dissolve in water. Therefore, it is very rare to detect either of them in rivers or lakes.

Nevertheless, studies on the effects of PDMS in the environment have been conducted using relatively high concentrations. No significant effects on fish or other aquatic life have been seen.

In fact, silicones can be used to protect wildlife. A major such use was the treatment with PDMS of otters caught in a large oil spill in Arctic waters. After using detergents to remove the oil, a PDMS coating gave their fur the necessary protection against the freezing waters until their natural waterproofing system could recover. They would not otherwise have survived.