About this device
A WAPI showing before (left) and after (right) position of the wax.
Keywords Water pasteurization, soybean wax, water, milk, pasteurization, indicator, reusable, thermometer, temperature, Soybean wax, clear plastic tube, string, wire
Uses Indicating when pasteurization temperature is reached
Authors McArdle
Status Implemented
Made? Yes
Replicated? True
Published 2008/01/19
Affiliations Appropedia user
SDGs SDG06 Clean water and sanitation
SDG09 Industry innovation and infrastructure
SDG11 Sustainable cities and communities
License data
Hardware CC BY-SA 4.0
Instructions data
Translation data

The WAPI (Water Pasteurization Indicator) is a reusable, inexpensive thermometer employing a plug of soybean wax which melts at 68˚C, just above the 65˚C or 149˚F pasteurization temperature for water or milk, at which point all disease-causing organisms (bacteria, viruses, and parasites) are killed.

Since the water is not heated all the way to boiling, and merely reaches the pasteurization temperature, time is saved and less fuel is consumed.

Construction and use[edit | edit source]

The hydrogenated soybean oil called Myverol 18-06 K (a food-grade emulsifier powdered wax) is encased in a small clear plastic tube, weighted with a metal washer. Fishing line or wire suspends the WAPI toward the bottom of the water container (where the water is coolest). The WAPI is oriented with the wax plug at its top, but after melting the wax flows to the bottom part. Then the user can remove the WAPI by the string or wire without contaminating the clean water with the fingers.

External links[edit | edit source]