During the 19th and early 20th century lead was used very widely in the major cities of the U.S. for water pipes because of its durability and malleability. Unfortunately, it was also the major source of lead-related health problems in the years before the health hazards of ingesting lead were fully understood. These hazards included stillbirth and high rates of infant mortality(1). Lead pipes were superceded by galvanized steel and copper. After World War II, copper became the predominant material selected for domestic water service and distribution in residential construction. Copper pipe still has over 80% market share for new indoor plumbing(2) with galvanized pipe and plastics being alternatives.
Some old homes and the service lines from the water mains to the homes still have lead pipes. For example, Providence Water in Rhode Island announced in May 2007 that some 25,000 of its total of 74,000 water connections are made of lead and will be replaced over a 15-year period(3). According to the Federal government(4), “Lead is unusual among drinking water contaminants in that it seldom occurs naturally in water supplies like rivers and lakes. Lead enters drinking water primarily as a result of the corrosion, or wearing away, of materials containing lead in the water distribution system and household plumbing. These materials include lead-based solder used to join copper pipe, brass and chrome plated brass faucets, and in some cases, pipes made of lead that connect your house to the water main (service lines).” In 1986, Congress banned the use of lead solder containing greater than 0.2% lead, and restricted the lead content of faucets, pipes and other plumbing materials to 8.0%.” This so-called “lead-free” brass can still legally contain up to 8% lead, and plumbing systems installed prior to 1986 can contain high levels of lead from both plumbing components and lead solder. The presence of lead in water from the tap is indicative of serious pipe corrosion that must be corrected for health reasons.
Galvanizing involves the application of molten zinc to pre-formed steel pipes to provide a corrosion resistant coating. However many galvanized pipes in old buildings were manufactured using zinc that probably contained high levels of lead, which is a common impurity in the zinc. It was not until 1986 that the Wheatland Tube Company became the first galvanized pipe manufacturer to be certified to ANSI/NSF Standard 61 for its hot dip galvanized pipe. Galvanized pipes are still common in older homes and many commercial buildings. Galvanized pipes will corrode over time, as indicated by the following corrosion symptoms:
- high levels of zinc or iron in tap water
- a “metallic“ taste of the water
- poor water flow due to blockage from mineral buildup
- discolored water (brown, red or yellow water)
Copper is widely used for plumbing pipes because of its excellent corrosion resistance and safety. It is also very easy to work with, as it is malleable and easily joined by fittings or soldering. Copper plumbing pipe comes in three types:
- “Type K” has the thickest walls
- “Type L” walls are less thick than K, but thicker than M
- “Type M” has the thinnest walls. Also, Type M is a hard tube, not easily bendable and is only supplied in straight lengths. It is most commonly used as the lowest cost tube in new buildings.
Despite its success as a plumbing material, copper pipe has sometimes failed well before its design lifetime, mainly because of pinhole leaks. This subject has been extensively studied for many years. Dr. Marc Edwards of the Virginia Polytechnic Institute and State University (Virginia Tech) believes and has testified during hearings of the U.S. House of Representatives and at City Council Hearings of the District of Columbia government that pinhole leaks in copper pipes are a major national problem.
1. W. Troesken, National Bureau of Economic Research, NBER Working Paper No. W9549, 2003 2. Copper Development Association 3. Providence Water, Press Release May 24 2007 4. Code of Federal Regulations (CFR Chapter 1, Part 141,143)