Metals

  • Metal components are durable, cost-effective, and do not pose health threats to users.

Key indicators

  • Metal components in contact with water meet Title 21 CFR Part 174.5 and 174.6.
  • All materials in contact with drinking water comply with NSF Standards 42 and 53 and any other technology-specific NSF standard (e.g., 44, 55, 58, 62).
  • Some metal components resist corrosion and discoloration from water, disinfectants, and galvanic action.
  • Untreated water qualities (such as pH, temperature, hardness, and water chemistry) can affect the bioavailability, and thus toxicity, of metals such as copper.
  • Metals employed as bactericides/chelates (e.g., colloidal silver, iron oxide, copper, or brass) remain subject to toxicity limits.
  • Metal components are able to withstand frequent cleaning.

Notes and exceptions

  • Metal components have strong appeal to some Indian consumer segments and are associated with value and durability.
  • Other Indian consumers state that metal devices appear “old-fashioned.”
  • Consumer appeal needs to be balanced against increased costs when metals are used.
  • Metals may be less durable than plastics when exposed to oxidants.

Supporting evidence

For the most up-to-date information, access the guidelines online:
http://www.path.org/hwts-design-guidelines/