Backwashing

Part of speech: noun

Definitions

1. The method of forcing liquid backward through a filter serves to clear it of debris while ensuring proper function and cleanliness within the filtration system
2. The process of pushing liquid in the opposite direction through a filter to remove trapped particles and maintain filter efficiency
3. A technique that involves flowing fluid backward through a filtering medium to dislodge accumulated impurities and restore filtering capability

Etymology: "Backwashing" is about as plain as English compounds get: "back" joined to "washing," with nothing hidden in the joint. "Back" comes from Old English "bæc," and "washing" is the gerund of "wash," which descends from Old English "wascan." Put together, the word describes washing or flowing in the reverse direction. The sense of reversal is what gives the term its use. Water pushed back through a filter bed dislodges the trapped particles that have built up on it, which is why the process matters in water treatment and in swimming pool and industrial filtration. The forward flow filters; the backward flow cleans the filter itself. Because the parts are so transparent, the word needs little explanation beyond its two components. Its meaning follows directly from the literal sense of each: the water goes back the way it came, carrying away what it had caught.

Synonyms: reverse flow, reflux