Think of a pool skimmer in a residential swimming pool like you would a gutter in a larger public swimming pool: it helps clean by skimming water and capturing floating debris — leaves, flower petals, dirt, twigs, dead insects and oil (sunblock) — before the waste can sink to the pool’s bottom.
Most skimmers on in-ground pools are built into its upper sides, where the suction draws debris and traps it. Most pool skimmers are accessed via the pool deck area through a trap door or hatch. The skimmer is also in a convenient location to attach a suction line for a pool vacuum.