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