A sedimentation area designed to remove pollutants from runoff before being discharged into a stream or pond. Catch basins are used during the times of heavy rainfall such as stormwater to accumulate contaminated water and store the unwanted pollutants, sediments, and debris. They are routinely used in mixed sewers watersheds as filtering captured large particles. Catch basins are seen as pretreatment for more advanced water treatment solutions and performs according to the design of the catch basin, including regular maintenance to reserve available storage in the sump to hold particles.