It's amazing the range of issues that are pro-plumber may run into in attending to a residential or commercial fix. To try to minimize some of these problems, some easy maintenance tips apply, and one that pros can always be mindful of is to make sure that all of the water lines or turned off before beginning work. When you first walk in the door to a plumbing repair job, it's important to think about the full spectrum of work that you will be doing to any appliances or lines in the home or space. It's not just a question of turning off the water when you know that the direct line will be spraying out all over your work area, it's also a question of making sure that all of the water lines are turned off in order to anticipate the unexpected.
Hazardous problems can sneak up on even the most seasoned plumbers because not all things are the same. An expert plumber may explain a elementary problem such as removing the temperature house off of the faucet. Now, on the face of it, that job doesn't seem to be very hard, and it would not necessarily require the water to be disconnected. But if, when pressure is applied, the cheap PVC breaks, you may have water splashing all over an area that was not intended to support this kind of situation. That's why it's a good idea to look at shutting down all of the water lines related to an area of the home were commercial space before starting to unhook anything.
More problems include finding all of the points of pressure of a system. You may think that you are unscrewing the correct valve apparatus, but if they plumber chooses unwisely, he or she may be allowing a water filled line to erupt into a living space. This situation can be made worse if the living spaces not set up to deal with a sudden water flow, which may damage materials such as carpet or upholstered furniture.
Plumbers have to be knowledgeable about pressure and its affects on water and pipes. Even a change in a line at the point of entry, such as a sink or toilet line, can cause a change of pressure elsewhere in that line, and send water spraying out of some point in a pipe or line. Also, turning off the lines of water will not cause a bunch of problems that make the water come with contact with things it cannot support.
In summary, the first step of solving most problems is shutting off the water so a plumber can complete his work. For the absent-minded, a checklist is a great idea, and even today's high-tech tools, such as cell phones, PalmPilots and the like, can store some handy lists that a professional can use upon entering a job site to remind themselves of what needs to be done first before getting into the nuts and bolts of the job.