My mom called me today because her UC unit stopped dispensing water (installed it 2 months ago and it's gorgeous and such a pleasure to use). Turned out she had flooded the counter accidentally and a tiny amount of water found its way under the sink, which activated the leak stopper. It's a tiny paper plug that unfolds (unflowers? when wet. And wouldn't ya know, they included two extra replacements. Problem solved in about 4 minutes. Handyman was admiring the design greatly and wanted info on the manufacturer. :D