Households around the world access water through an intermittent piped water supply; however, delivery of water in these systems is often unpredictable, creating a burden for households waiting to collect water and utilities managing its distribution. We present NextDrop, a system that allows water operators to report information through existing networks of mobile phones and use that information to relay water delivery times to households. NextDrop has been deployed for six months in Hubli, a mid-sized city in India. We describe the NextDrop system, evaluate the accuracy of data collection, and present data collected through NextDrop. The experience of NextDrop shows that crowd-sourced observations can be used to monitor the operation of a complex infrastructure system in a low-resource setting.