Users are clearly informed when device components require replacement.
Indicator anticipates end of life so users have time to procure replacement elements.
>80% of user-testers correctly interpret end-of-life indicators.
End users demonstrate motivation to replace expired components before total failure.
Notes and exceptions
Indicator strategies include:
If a safe storage container is included in the device design, flow-cutoff indicators should reduce flow, but not cut it off completely. This will enable users to keep the benefit of safe storage even if the filter element is no longer improving the water quality.
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/