Grünbein has a repeated use of bathtubs and drains for metaphors in his poems. From his first collection:

Bathtubs

What adorable objects bathtubs are, enameled
.........and sleek and altogether
..............unapproachable with their

heroic curves of wrought-iron
.........old ladies still frisky
..............after the menopause.

Typical chattels (when did
.........one of these ever get up
..............and go) and nevertheless

continually replenished, all the dirt
.........dissolved and swilled
..............into the sewage system

is forced through that narrow
.........stopper hole in the base. Real sui-
..............cide machines on their

stumpy legs, warm-water-beds
.........with just enough room for a sing-
..............le copulating couple

in so many apartments, something like
.........an oasis of nostalgic
..............bubbles.

And from a more recent collection, in a poem titled "In Front of an Old X-Ray":

The bodies are gone. A posthumous tidiness reigns
In the empty apartment, spring-cleaned from the mirrors
To the stains in the bath. At the bottom of the tub
Curls one single hair, last surviving trace of a species
That cleans up after itself and washes after mating.
How peaceful are the windowsills with their dead flies--
But even here terror likes to call.

And from "Europe After the Last Rains":

A river, but what's a river when the city sinks
before its waves, reflecting back the blaze.
A murky sky, all ablink with dead fishes,
an emergency exit, the door with seven seals--
a plug for the nearest open sea?