Knuckles of rain
rapping on the grooves
of the tin roof

Water coursing its way
through rooftop valleys
along gutters
down pipes
into plastic tanks

Knuckles of fingers
tapping those tanks
listening
searching for the hollow
measuring

Easier, safer
than leaning a buckled ladder
over uneven bracken slopes
unscrewing the filters
peering in
guessing

The first tank, 1983,
was corrugated iron.
Rust took its toll and now
the classic grooves
lay on their side
shelter for the firewood