HWTS Design Guidelines
- Metal components are durable, cost-effective, and do not pose health threats to users.
- 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.
For the most up-to-date information, access the guidelines online: