Why do you need commercial plumbing. Residencial plumbing is diffrent the commercial plumbing in many ways. It is more important in commercail plumbing to have your pipes checked and maintained regularly, so as to avoid major plumbing problems later on. You should always make it a point to keep your drains clean and pressrue test the water line on a regular basis. The owner of the business or building contactor should always keep the phone numbers of commercial plumbing services for the installation, repair, and replacment needs including: sewers and drains, faucets, showers and tubs, sinks, toilets waterlines, disposers, dishwashers, pipe work and septic tanks.