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