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EPA’s Research Helps to Control Corrosion and Reduce Release of Metals Into Our Drinking Water Distribution Systems

What is Corrosion, Scaling and Metal Mobility?

Corrosion is the degradation of metal. In water distribution pipelines, valves, and fixtures, it can decrease the quality our drinking water. Corrosion product solids can be:

  • iron,
  • copper, and
  • lead carbonates and oxides.

Scaling is the buildup of scale (hard mineral coatings) and corrosion deposits on or in the distribution system piping and storage reservoirs. These deposits are made up of solids and sediments. The sediments consist of corrosion by-products and seperated solids, such as

  • manganese oxides,
  • aluminum hydroxide,
  • calcium carbonate, and
  • solids that carry over from water treatment plants.

Metal Mobility is the ability of metals to move freely and easily.

Why is EPA researching this area?

Corrosion is a big problem for our drinking water distribution systems. It is caused by oxidation or chemical action. EPA has estimated that $138 billion will be needed over the next 20 years to maintain and replace existing drinking water systems. $77 billion of this will be dedicated to repairing and rehabilitating pipelines.

Also, contamination entering our distribution systems is responsible for a significant percentage of waterborne disease outbreaks reported in recent years. EPA’s research into corrosion and its related reactions lead to using safer materials in the production of plumbing fixtures and the development of the best corrosion control treatments.

Corrosion by-products that form on the surface of pipes and fixtures affect the solubility of lead, copper, and iron. This ultimately affects their levels at the consumer’s tap. Other types of scales (hard mineral coatings) can form flow barriers on metal pipe surfaces, which can reduce the release of metal into distribution systems water. Corrosion by-products and other solids that accumulate in a distribution system can adsorb trace contaminants, such as arsenic. The contaminants are then subject to potential re-release into the water, causing increased levels at the consumer’s tap.

What has EPA done in corrosion research?

EPA research has produced several corrosion control strategies that use various combinations of

  • materials selection,
  • materials removal,
  • metal solubility, and
  • chemical water treatment.

Chemical water treatment programs consist of either manipulating the general water chemistry or adding a chemical to the water to produce a less corrosive water quality.

Products

Research Products Listed by Goal

EPA goals aim to reduce contamination within drinking water distribution systems and to preserve the structural integrity of drinking water distribution systems. The program uses:

  • field,
  • bench-scale,
  • pilot studies, and
  • a variety of solids and water analysis tools

to understand the nature of:

  • various types of corrosion,
  • corrosion by-products, and
  • scales in relation to metal contaminant release.

The research supports current rules and regulations, and provides the scientific basis for making new rules.

Goal: Provide the Office of Water, states, local authorities, and utilities with data and tools for characterizing and managing chemical and microbial contaminants in distribution systems.

  • Collect and interpret data to assess the stability of arsenic in water distribution systems
  • Report the effect of oxidizing conditions on metal releases, corrosion rate, and scale properties of distribution system materials
  • Report the characterization and prediction of scale formation (including aluminum) in distribution systems
  • Report the detection of opportunistic pathogens (Escherichia coli, Aeromonas, and Mycobacterium) in biofilms, using molecular detection techniques
  • Collect and interpret data on treatment conditions that might enhance the solubilization of arsenic-containing iron oxides within the distribution system
  • Report on corrosion chemistry relationships and treatment approaches
  • Report on the association of arsenic with iron particles, corrosion by-products, and sediment in drinking water distribution systems

Goal: Provide the Office of Water and other stakeholders with new data and tools for monitoring, designing, managing, and understanding the risks associated with contamination of distribution systems.

  • Report on the link between the distribution system and Mycobacterium avium complex found in clinical cases
  • Report on studies evaluating distribution system variables associated with microbial health effects
  • Conduct comparison studies of Mycobacterium disease isolates and distribution system isolates
  • Report on biofilm and regrowth issues associated with nontuberculous mycobacteria
  • Report on the characterization and prediction of disinfection by-products (DBPs) in distribution systems
  • Report on the performance and net cost targets for remote, on-line structural integrity monitoring for drinking water distribution systems
  • Create a synthesis document: a state-of-the-science report on management and control of water quality in distribution systems (Note: A synthesis document more effectively communicates research results to clients.)

Research Products Listed by Product Type

Data and Databases

  • Data to assess the stability of arsenic in water distribution systems
  • Data on the treatment conditions that might enhance the solubilization of arsenic-containing iron oxides within the distribution system

Reports, Documents, Manuals, and Reviews

  • Report on the effect of oxidizing conditions on metal releases, corrosion rates, and scale properties of distribution system materials
  • Report on the characterization and prediction of scale formation (including aluminum) in distribution systems
  • Report on corrosion chemistry relationships and treatment approaches
  • Report on the association of arsenic with iron particles, corrosion by-products, and sediment in drinking water distribution systems
  • Interim report on management and control of water quality in distribution systems
  • Report on the link between the distribution system and Mycobacterium avium complex found in clinical cases
  • Report on studies evaluating distribution system variables associated with microbial health effects
  • Report on biofilm and regrowth issues associated with nontuberculous mycobacteria
  • Report on the characterization and prediction of DBPs in distribution systems
  • Report on the performance and net cost targets for remote, on-line structural integrity monitoring for drinking water distribution systems
  • Synthesis document: a state-of-the-science report on management and control of water quality in distribution systems (Note: A synthesis document more effectively communicates research results to clients.)

Additional Studies

Comparison of Mycobacterium disease isolates and distribution system isolates

Who may I contact if I have additional questions?

Darren Lytle
(513) 569-7432

Michael Schock
(513) 569-7412

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