If a plumber needs to do major repairs to your house, the work could call for a permit. You'll want this since a permit provides added assurance that the work is done correctly. Having this added measure in place means an inspector will check the work your contractor or plumber does to ensure he or she did the job correctly. If you ever plan on putting your house or commercial building on the market, a real estate agent and prospective buyers will also want to check any large work you did to make sure it was done properly.
Our old water heater let go late at night and I started calling for help the next morning. Ben with Bayz called back within 30 minutes and offered to come out in an hour to look over. He came by right on time, provided an estimate for replacement (the heater had to go), and confirmed that the new heater could be installed today. I gave the go-ahead and Ben immediately began work to fully drain and then remove the old heater. He was personable and happy to explain what he was doing - and why - and after about an hour's work he let me know that he was going to pick up the new heater and would return in about an hour - which he did. Two hours after he returned I had a brand new fully functional water heater. I highly recommend Bayz as they provided professional service when promised and offered helpful suggestions/ideas when asked.
The word "plumber" dates from the Roman Empire. The Latin for lead is plumbum. Roman roofs used lead in conduits and drain pipes and some were also covered with lead, lead was also used for piping and for making baths. In medieval times anyone who worked with lead was referred to as a plumber as can be seen from an extract of workmen fixing a roof in Westminster Palace and were referred to as plumbers "To Gilbert de Westminster, plumber, working about the roof of the pantry of the little hall, covering it with lead, and about various defects in the roof of the little hall". Thus a person with expertise in working with lead was first known as a Plumbarius which was later shortened to plumber.