De or het plombering?

The correct Dutch article is:

de plombering

Rule Words ending in -ing: almost always de. See the rule

How to use plombering

the plomberingde plombering
this plomberingdeze plombering
that plomberingdie plombering
our plomberingonze plombering
your plomberingjouw plombering
every plomberingelke plombering
which plombering?welke plombering?
a big plombering / the big plomberingeen grote plombering, de grote plombering