21 CFR 211.48 - Plumbing

What it says

Potable water must supply pharmaceutical water systems, drains must be of adequate size and, where connected directly to a sewer, provided with an air break or mechanical device to prevent back-siphonage, and water used in manufacturing must be suitable for its intended use with appropriate specifications for chemical and microbiological quality.

Paraphrased for plain-language clarity. Always verify against the current published regulation text.

What it means in practice

• Pharmaceutical water quality requirements scale with intended use - water for injection carries a materially higher purity and microbiological standard than water used for equipment cleaning or as a starting material for potable-grade uses.
• Back-siphonage prevention is a specific, physical design requirement protecting the water system from contamination originating in the drain or sewer connection, not just a general cleanliness expectation.
• Pharmaceutical water systems require their own ongoing monitoring and periodic system review, similar in principle to other utility qualification, since water quality can drift over time even after a successful initial qualification.

What FDA inspectors look for

• Whether water system monitoring data, chemical and microbiological, is trended over time and reviewed for drift, not just checked against a pass or fail limit at each individual sampling point.
• Whether the water system's actual qualified grade matches the grade required for its specific downstream use throughout the facility.
• Whether periodic system review and requalification of the water system occurs on a defined schedule, accounting for seasonal or usage-pattern variation.

Related regulations