Concealed Overflows

(1)  A dishwashing sink and a food preparation sink shall not have concealed overflows.

Article Ontario Regulation 332/12 Building Code,   O. Reg. 332/12: BUILDING CODE ( © Queen’s Printer for Ontario, 2021.

Note : What is a concealed overflow. A sink overflow is a hidden channel running along the underside of the sink basin. It’s typically unseen from both below and above, but you may have seen it as the two small holes close to the rim of your sink