• Device minimizes user intervention during operation and is easy to operate for primary users.

Key indicators

  • Simplest operating sequence is fill, wait, dispense.
  • Users are not required to learn multi-step procedures to produce safe water.
  • The operating sequence can be depicted graphically and requires little or no user assistance.
  • User actions required to operate the device fit their mental models of how devices should operate.

Notes and exceptions

  • Avoid introducing design features such as lids or taps that require unfamiliar user actions such as twist-push fittings or pinch valves on water outlets.