Wiktionary
mop water
alt. 1 The dirty water which is left over after one mops. 2 (context figuratively English) Any water which is reminiscent of such dirty water. n. 1 The dirty water which is left over after one mops. 2 (context figuratively English) Any water which is reminiscent of such dirty water.
Usage examples of "mop water".
And he batted around the ward bigger than ever, spilled a bucket of mop water under the Nurses’.
He flicked drops of dirty mop water into culture dishes, waxed the guinea pig's protein pellets, unplugged incubators, and altered figures on charts.