Is the sink useful

Hint 1 of 5:

You could wash off the muddy coin if you had hot water.

Hint 2 of 5:

EXAMINE PLUMBING to see why the hot water doesn't work.

Hint 3 of 5:

FIX PLUMBING then OPEN DRAIN and CLOSE DRAIN to remove cold water.

Hint 4 of 5:

Got anything that is dirty ( you could wash it to kill time ).

Hint 5 of 5:

TURN ON HOT WATER then CLEAN COIN then LOOK AT COIN.