Most aerial retardants are primarily water (85%), fertilizer (10%), and coloring (usually 5% iron oxide). In most circumstances, they can be removed with plain water, but if dried, may require the use of a power washer. The iron oxide can penetrate some materials and be difficult to remove, requiring additional solvents.
Gel retardants applied from the ground are also primarily water combined with detergents and can be removed with plain water. Some gels, however, have coloring agents which can be difficult to remove and may require professional assistance.
Although modern retardants are not considered toxic, it is a good idea to avoid making puddles when cleaning so that pets and wildlife do not ingest this material. Pets should be shampooed to remove any material on them, although the main effect is just temporary drying of the skin.
Most retardants, particularly aerial sprays, are designed to biodegrade and fade over time, so they gradually disappear from the landscape.
For a more complete discussion of this topic, go to Removing Forest Fire or Wildfire Retardants.
