Pro Plumbers

Present-day water-supply systems use a network of high-pressure pumps, and pipes in buildings are now made of copper,[25] brass, plastic (particularly cross-linked polyethylene called PEX, which is estimated to be used in 60% of single-family homes[26]), or other nontoxic material. Due to its toxicity, most cities moved away from lead water-supply piping by the 1920s in the United States,[27] although lead pipes were approved by national plumbing codes into the 1980s,[28] and lead was used in plumbing solder for drinking water until it was banned in 1986.[27] Drain and vent lines are made of plastic, steel, cast-iron, or lead.[29][30]
Bacteria have been shown to live in "premises plumbing systems". The latter refers to the "pipes and fixtures within a building that transport water to taps after it is delivered by the utility".[34] Community water systems have been known for centuries to spread waterborne diseases like typhoid and cholera, however "opportunistic premises plumbing pathogens" have been recognized only more recently; Legionella pneumophila discovered in 1976, Mycobacterium avium, and Pseudomonas aeruginosa are the most commonly tracked bacteria, which people with depressed immunity can inhale or ingest and may become infected with.[35] These opportunistic pathogens can grow for example in faucets, shower heads, water heaters and along pipe walls. Reasons that favor their growth are "high surface-to-volume ratio, intermittent stagnation, low disinfectant residual, and warming cycles". A high surface-to-volume ratio, i.e. a relatively large surface area allows the bacteria to form a biofilm, which protects them from disinfection.[35]
My Mom is in her eightys. I called a plumber in Aug 2012, replaced the McDonnell/Miller LWCO low water cut off 47/2 $675.. Same plumber was called Jan 8,2013 back. He trouble shoot the problem and replaced the same unit, yet I still have the problem. After the heat come on for about 15 mins/ goes off.the pipes connecting to the MM LOCO the vibrating starts, shakes, and makes a loud noise. The boiler is steam, I know it's old. Do I call the same plumber or call someone differently?

Wooden pipes were used in London and elsewhere during the 16th and 17th centuries. The pipes were hollowed-out logs, which were tapered at the end with a small hole in which the water would pass through.[16] The multiple pipes were then sealed together with hot animal fat. They were often used in Montreal and Boston in the 1800s, and built-up wooden tubes were widely used in the USA during the 20th century. These pipes, used in place of corrugated iron or reinforced concrete pipes, were made of sections cut from short lengths of wood. Locking of adjacent rings with hardwood dowel pins produced a flexible structure. About 100,000 feet of these wooden pipes were installed during WW2 in drainage culverts, storm sewers and conduits, under highways and at army camps, naval stations, airfields and ordnance plants.
Wall thickness does not affect pipe or tubing size.[20] 1/2" L copper has the same outer diameter as 1/2" K or M copper. The same applies to pipe schedules. As a result, a slight increase in pressure losses is realized due to a decrease in flowpath as wall thickness is increased. In other words, 1 foot of 1/2" L copper has slightly less volume than 1 foot of 1/2 M copper.[citation needed]

The word "plumber" dates from the Roman Empire.[3] The Latin for lead is plumbum. Roman roofs used lead in conduits and drain pipes[4] and some were also covered with lead, lead was also used for piping and for making baths.[5] 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".[6] Thus a person with expertise in working with lead was first known as a Plumbarius which was later shortened to plumber.