Q: I was at a rent meeting where the term “catchment area” was used to describe a neighborhood. I thought it should be “cachement area,” along the lines of “cache,” the geeky word for memory storage. But when I tried to email someone about the meeting, the spell-checker suggested changing “cachement” to “catchment.” What’s the story?
A: Your email spell-checker is right this time. The correct word is “catchment,” not “cachement.”
I wouldn’t be surprised, however, if the “cache” version catches on in this digital age. In fact, I got nearly 7,000 hits when I googled it, though that’s piddling compared with the nearly 5.5 million hits for “catchment.”
The term “catchment area” usually refers to a natural drainage area that “catches” or collects rainwater draining into a river or other body of water. It’s also called a “catchment basin.”
The shorter term “catch basin” usually refers to a receptacle that collects surface drainage or runoff. If you look under one of those grates that you see alongside roads, you’ll often find a catch basin.
The word “catchment,” in its drainage sense, entered English in the mid-19th century. The first published reference in the Oxford English Dictionary is from an 1847 book on hydraulic engineering: “A great portion of the catchment basin is very little raised above the level of the lake.”
But back to the rent meeting you attended and the usage you found so puzzling. Why is a neighborhood called a “catchment area”?
It turns out that in the mid-20th century the expression came to be used figuratively for a geographical region served by a specific school, hospital, or other institution.
In other words, the institution would “catch” students, patients, or whatever from its “catchment area.”
The first citation in the OED for this usage is from a 1959 article in the Times of London that describes the area served by the Leeds prison as a “catchment area” for the institution.
Of course one can catch lovers of whodunits as well as the crooks who’ve done it. A 1960 citation from a library journal defines “catchment area” as “the area from which readers may be expected to be drawn.”