Chances are that you yourself have multiple insurance policies but however prepared as you may be, when you call for a plumber, you need to make sure that they are properly insured as well. Accidents are rare, but should an accident happen to you, you need to make sure that you won't be ruined financially. Plumbing insurance is a special type of insurance that protects plumbers and the clients they do business with.
One thing plumbing insurance protects against is theft. When you allow strangers to enter your home, you want to be sure your possessions are safe. While a plumber working in your home is unlikely to steal anything, it is still comforting reminder when there are strangers working in your home.
Another major part of plumbing insurance is coverage for damage from accidents. Whenever plumbing is involved, there is a risk of water damage. Plumbers are only human, so as capable as they might be, they still can make a mistake, which could result in water spraying everywhere. Water damage restoration isn't cheap as it often requires removing floors and drywall, drying the area, and replacing and repainting what was damaged. As long as the plumber is insured, you won't have to worry about either you or the plumber going broke trying to pay for damages.
Plumbing insurance also covers injuries sustained by the plumber or by the plumbing project. When working in cramped spaces with welding guns, injuries aren't that unlikely. Everything from bumps and bruises to major gashes and burns can occur during a simple plumbing project. Also, if the plumbing job somehow results in you or a family member getting injured, any resulting medical bills will also be covered. Health care isn't cheap, even with minor injuries, so this coverage is important.
The last thing you want is a dispute between you and your plumber about who is liable in a certain situation. Your best course of action is simply to make sure you go with an insured plumber to begin with. The insurance not only protects both parties for accidents that might occur, but it is also an indicator that the plumber is legitimate and reputable.