from a reader – and response – which suggests that we should refrain from using plastics as water containers – and at least in the context of pet water bowls – stick to glass.

via Wikimedia Commons
Dr. Fox does not address stainless steel, or fabric-based bowls; we’ll attempt to follow up with him.
Two-Bit Dog – Dr. Fox’s website. The Washington Post – an excellent paper with a generally excellent website – doesn’t provide a link to Dr. Fox’s columns.
See also “Microwave Safe – Not!” from the the always-excellent PumpHandle, cross-posted by revere at Effect Measure.