Users can easily confirm that the device is functioning properly.
>80% of user-testers correctly interpret product status indicators.
Safe water container is not contaminated by typical malfunctions (clogged filter element or element is incorrectly inserted).
Notes and exceptions
Failure indicators should be obvious and unambiguous.
In the absence of failure indicators, the device should prevent untreated water from contaminating the safe water container.
Qualitative and quantitative risk assessments (e.g., failure mode and effects analysis, risk priority numbers, and fault tree analysis) can be conducted to understand the likelihood and the impact of misuse.
For the most up-to-date information, access the guidelines online: http://www.path.org/hwts-design-guidelines/