| Locally-manufactured ceramic water filters are one effective technology for household drinking water treatment. During manufacturing, silver nanoparticles or silver nitrate are applied to increase bacterial inactivation. There is currently no recommended method to test silver application or residual concentrations during manufacturing. We identified six commercially-available silver test strips, kits, and meters, and evaluated them by: 1) measuring in quintuplicate 6 samples from 100-1,000 mg/L (application range) and 6 samples from 0.0-1.0 mg/L (residual range) of silver nanoparticles and silver nitrate to determine accuracy and precision; 2) conducting volunteer testing to assess ease-of-use; and, 3) comparing costs. We found no method was appropriate for testing silver nanoparticles. For silver nitrate, accuracy ranged from 3-100% error, most methods were precise, volunteers found test strip methods easiest but meters most reliable, and cost for 100 tests were 36-1,600 USD. No currently available method met criteria for recommending to filter manufacturers. We recommend development of field-appropriate methods that can measure application and residual concentrations and test silver nanoparticles. |
