• Best: the upper container should match the volume of a typical water collection vessel (±12 L) so that the user can fill the upper container as quickly as they wish with minimal spillage or mess.
  • Threshold: the user should be able to fill the upper container with two pours.

Key indicators

  • Upper container capacity matches size of water collection vessel.
  • Filler opening >25 cm diameter.
  • Concave container lid to minimize spills.
  • Lid design affords a surface where components can be placed during cleaning, as well as a place to store cups or drinking vessels.
  • Pre-filter mesh size does not restrict inflow.
  • Height the transfer vessel must be lifted to in order to fill the device does not exceed shoulder height of average user.
  • The device should support the weight of a typical full water collection vessel since users may rest it on the rim during filling.

Notes and exceptions

  • Permeability of pre-filter, filler opening size, and device lid design will affect ease of filling.
  • Devices that are inconvenient, messy, or difficult to fill reduce consumer appeal.
  • The volume of the untreated water container should correspond to the volume of common local vessels used to store or transfer water (in India: ±12 L).
  • Product lids are necessary to reduce physical contamination from dirt, dust, insects, and vermin.
  • Lid design should minimize the splashing or spilling of untreated water and risk of cross-contamination with the safe water container or tap.

Water being poured into a storage container.

Repeatedly lifting the storage vessel to fill the device is tiring. The device should be easy to fill quickly and without messes. Photo: PATH.