rinse, wash
滌 centers on cleaning with water: rinsing or washing something to remove dirt or impurities.
滌 combines 氵 (water) with 條, which likely contributes the sound and the idea of a long, flowing action, suggesting washing or rinsing with water.
Water 氵 flows over a long, branch-like shape 條, like rinsing something under a stream until it is clean.
For デキ, imagine a deck being washed with water: deck -> デキ, and the water 氵 rinses the deck clean.
washing; cleansing; cleaning; irrigation