 Where do you look for the watermark? Plumbing and drainage products must be certified with license details listed in the Watermark Product Database, located on the Watermark website. This database allows you to search for licenses and products by Watermark license number, brand name, model name, model ID, licensee name, or product description. So, to make sure that it's safe and fit for purpose, always look for the Watermark. Thank you.