"Basin" is the first translation word given in Lewis and Short. And a labrum can be moveable, as Cicero Epistulae ad Familiares 220.127.116.11 makes clear (to Terentia):
TULLIUS S. D. TERENTIAE SUAE
In Tusculanum nos venturos putamus aut Nonis aut 18.104.22.168 postridie. ibi ut sint omnia parata. plures enim fortasse
nobiscum erunt et, ut arbitror, diutius ibi commorabimur.
labrum si in balineo non est, ut sit; item cetera quae sunt ad
victum et ad valetudinem necessaria. 5 Vale.
I love his letters.
This is basically:
We think we'll get to our place in Tusculum on the Nones or the day after. Make sure everything's ready there. After all, there might be some more people with us and I reckon we'll stay there pretty long. If there isn't a basin in the bath, there should be. Same goes for whatever else we'll need to eat and be well.
Excellent rendering. The labrum usually referred to the place where the bathers splashed their neck and face after bathing in the cal(i)darium. It might not be clear to students that a sentence such as 'Labrum implemus et nos lavamus' for a Roman would not normally refer to an individual bathtub in which a person bathes. Cf. Fagan, Bathing in Public in the Roman World (Michigan, 199).