De or het vochtophoping?

The correct Dutch article is:

de vochtophoping

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

How to use vochtophoping

the vochtophopingde vochtophoping
this vochtophopingdeze vochtophoping
that vochtophopingdie vochtophoping
our vochtophopingonze vochtophoping
your vochtophopingjouw vochtophoping
every vochtophopingelke vochtophoping
which vochtophoping?welke vochtophoping?
a big vochtophoping / the big vochtophopingeen grote vochtophoping, de grote vochtophoping