|The Romans' network of pipes was used to transport clean water to public bath houses and to also recall the used water.|
By Greg Harkness
Water is crucial to our survival. Without it, crops won't grow, animals can't survive and people would perish from dehydration. Contaminated water, however, can be just as harmful.
In a survey conducted earlier this year in India's third largest city, Bengaluru, half of respondents claimed they had a friend or family member who became infected with a water-borne illness within the last 12 months. As a result, nearly 90 percent of all sicknesses severely affecting the health of India's residents are a result of toxic chemicals including lead found in the water supply.
India's Advisor to the Quality Council of India (QCI), Dr. Thuppil Venkatesth attested that India is on the verge of becoming the world capital of lead poisoning because of the dangers surrounding the country's water distribution system.
But contaminated water isn't an issue reserved for heavily-populated countries.
In Europe, Ireland has also faced similar problems, with more than 30,000 households estimated to be at risk of lead poisoning from drinking water supplied through lead pipes. While the European country's Environmental Protection Agency (EPA) has ordered the last known four kilometers of lead pipe in public water mains to be replaced, it has warned that other lead mains dating as far back as Victorian eras may unknowingly exist.
Ireland continues, nonetheless, to take firm measures to reduce the possibility of poisoning and estimates that only 2 percent of its remaining water mains are at lead levels exceeding the country's current restrictions.
The History of Lead
Around 50 A.D., ancient Romans developed piping systems using a network of aqueducts, which earned them credit for the development of modern plumbing. Their network of pipes was used to transport clean water to public bath houses and to also recall the used water.
In building their water network, the Romans used lead because of the material's high malleability and relatively low melting point. Not only was the resource ideal for metal working and crafting, but it was highly resistant to corrosion and provided strength and durability at a more reasonable cost than other resources at that time.
For centuries, the sturdy material was used for water applications. Over time however, it was discovered that the natural resource was poisoning people.
According to the New York Department of Health, lead is extremely harmful to humans' neurological, gastrointestinal and reproductive systems. Specific side effects may include seizures, peripheral neuropathy, nausea, colic, dyspepsia, miscarriages/stillbirths, anemia, and hypertension.
When it comes to children, being exposed to lead carries even more dangerous side effects that can influence their growth, behavior and ability to learn because they are still in a developmental stage.
As understanding of the dangers of lead increased, the use of the heavy metal was eventually phased out and replaced by alternatives such as copper, bronze, iron, and brass.
Protecting the Public
In 1974, the U.S. Congress passed the Safe Drinking Water Act (SDWA) to protect public health by regulating the management of drinking water throughout the country. The law gave power to the government to set national standards for drinking water, including how it would be managed and accessed. Additionally, it gave the government the responsibility to mandate acceptable and unacceptable levels of natural and man-made contaminants.
As time, technology and resources have progressed, so have the restrictions, leading to the amendment of the SDWA laws in 1986 and again in 1996. The 1986 revision added Section 1417 to the SWDA, which mandated that all pipes, solder, pipe fittings, and plumbing fixtures be lead-free when the water flowing throughout the system would be intended for human consumption.
Section 1417 advanced to define "lead-free" for pipe and fittings to be no more than 8.0 percent lead by weight and solders and flux to be no more than 0.20 percent lead by weight. Additionally, plumbing fittings and fixtures were limited to no more than 4.0 percent measured by dry weight. In 1996, revisions were made to Section 1417 requiring that water systems issue a public report on their water quality each year.
While the federal government maintained the responsibility of dictating the highest levels of allowable lead content through the SDWA and its subsequent amendments, California elected to pass a state law in 2006 requiring even stricter standards to be enforced. Shortly thereafter, the same standards were adopted by Vermont in 2008 and Maryland in 2010, with all three states allowing two to four years for compliance after the initial signing of the laws.
The standards set forth by the states required that wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures have a weight average of no more than 0.25 percent lead, with the 0.20 percent lead content limit for solder and flux remaining unchanged.
In 2011, the decision was made by the federal government to implement the states' tighter standard across the board with the signing of the Reduction of Lead in Drinking Water Act.
On January 4, 2014, the new act, which serves as an addendum to the rules established by SDWA, will require that all products in contact with drinking water have a 0.25 percent maximum lead content by weight, as opposed to the 8 percent standard of previous regulations.
Though it's tough to estimate how much of the current plumbing infrastructure will be affected by the new regulations, the Plumbing Manufacturers Institute believes that nearly all homes built prior to the 1980s still have lead solder connecting copper pipes.
Seeking an Alternative
In order to meet the new standard, manufacturers of products used for the transportation and distribution of drinking water are working with material suppliers to secure new lead-free alternatives. Depending on the product, solutions meeting the new standards may include low-lead brass alternatives, stainless steel, plastic polymers, and composite materials.
|Sensus' iPERL® residential meter. The tube manages water flow to a home and is connected to two graphite electrodes that measure water usage.|
One of the most common types of materials used for pipe fittings, valves and water meter housings is traditional brass alloys. These tools are generally made from a combination of lead, copper and zinc materials, and often contain 2 to 4 percent lead content by weight. Further, in order to meet the new federal restrictions, brass manufacturers are looking to reconfigure the mix of materials used in order to lower the percentage of lead contained in brass alloys.
Some have already accomplished this by substituting lead with bismuth or silicon to create a lead-free alternative. The new material, however, is more difficult to cast, harder to machine and results in faster tool wear. Properties of lead-free brass alloys provide a similar performance to their lead-containing counterparts.
Stainless steel is another alternative available to manufacturers. Its higher finished-part cost has typically limited its use, but with the new standards, the material and production costs of stainless steel compared to lead-free brass are now closer aligned. Stainless steel is considered a solid solution for many manufacturers because it allows engineers to design parts with similar design principles as brass.
Engineering thermoplastics is another lead-free alternative being considered to meet this standard. The plumbing industry has a long history of designing parts such as fittings, valves and meters in thermoplastic material because of its resistance to corrosion and mineral buildup. With no heavy metals, engineering thermoplastics have high levels of thermal insulation and offer more design freedom than metal parts.
With the new legislation, parts manufacturers are looking at these and other material options to meet the new standards. Sensus is one such company.
Early in their design, Sensus USA Inc., a global leader in utility infrastructure systems and resource conservation, began evaluating 12 different materials to replace metal in the prototype flow tube of its iPERL® residential meter. The tube manages water flow to a home and is connected to two graphite electrodes that measure water usage.
Sensus sought an alternative solution that would meet or exceed the new restrictions, all while maintaining the integrity of their product. After conducting a series of tests for strength and durability on both metal and thermoplastic options, the company selected Xtel® PPS alloys manufactured by Chevron Phillips Chemical Company LP for the project.
Xtel® PPS alloys are glass-reinforced polyphenylene sulfide thermoplastics that resist rust and corrosion and can withstand extreme temperatures. They also have low moisture absorption and high creep resistance, meaning the plastic can maintain structural stability against high water pressure, even over an extended period of time.
By using Xtel® PPS alloys, Sensus achieved zero percent lead content in the flow tube - the primary device that interacts with the drinking water - and thus exceeded the regulatory requirement. The company also found that the new meter designed with Xtel® PPS alloys was able to withstand operating pressures nearly twice as high as its predecessor.
As the Reduction of Lead in Drinking Water Act goes into effect in January, many other part manufacturers will be looking for lead-free replacement materials, including non-metal alternatives.
Chevron Phillips Chemical offers a variety of non-metal alternatives, including engineering thermoplastics for various applications and lead-free certified high density polyethylene (HDPE) water pipe available through the company's Performance Pipe division. To learn more, visit www.cpchem.com.
About the Author: Greg Harkness is business development manager for Chevron Phillips Chemical's Engineering Polymers business and specializes in new application development. Harkness has more than 29 years in the industry and specializes in work with Ryton® PPS and Xtel® PPS alloys.