Check exposed pipes in your home under the sink, connected to appliances, or in the ceiling of an unfinished basement, and look for light gray-coloured flexible pipes. Typically it will be stamped with “poly B potable,” “CSA-B 137.8.” or “PB2110.” Keep in mind that not all plastic piping is Poly B, you might have PEX plastic piping which is typically white or translucent.