In this instance, I think their use of the French term is possibly a bit woolly, I feel sure what they are referring to is the usual kind of (e.g.) cast-iron grating commonly placed below outdoor taps, in order to take waste water into the sewer system (eaux usées).

In other contexts this can also be referred to as a 'regard', though there are other, more usual, words for it.

You might also call it a 'trap', though strictly speaking, that refers to the anti-odour siphon mechanism, and not purely to the drain itself; however, a 'floor trap' is a common term for this kind of drain, as let into service area floors etc.


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Note added at 2 hrs 23 mins (2005-09-28 16:53:31 GMT)
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Philippe has reminded me of the more usual word: 'avaloir'

But a non-plumbing expert (and this IS catering, right?) is quite likely to use the term inaccurately...

It may be a drain with a removable lid, rather than a grating as such, which could explain the usage...