Sroto: Water Source Check

When several households in a neighborhood share a few wells, pumps, and ponds, and people begin feeling unwell, the central question is which source may be connected to the issue.

Sroto helps a neighborhood investigate that question together through structured community reporting and statistical analysis.

Two Roles:

1. Household:
• Join a neighborhood by scanning a setup code or opening a setup file
• Record which water sources your household used each week and in what proportions
• Note whether water was boiled before drinking
• Note whether anyone in your household was unwell that week
• Display your weekly report code on screen for the neighborhood collector to scan in person
• Scan the village result code to see the community comparison on your own phone

2. Collector:
• Set up the list of neighborhood water sources and display the village setup code
• Scan weekly report codes from households in person or open report files
• Record weekly reports for households that do not have a smartphone
• Compute Bayesian inference on device across all collected reports
• Display the village result code and share an aggregate visual result card

Key Characteristics:
• Proportional usage: Handles households drawing water from multiple sources in varied amounts
• Boiling consideration: Accounts for the protective impact of boiling water
• Time factors: Considers the timing of when people began feeling unwell
• Balanced evidence: Accounts for households that drank from a source and remained well
• Measured confidence: Clearly communicates when collected data is insufficient to draw a conclusion
• Local security: Designed to prevent duplicate influence from repeated scans of the same report

Important Boundaries:
• Sroto never diagnoses medical conditions or names medical conditions
• Sroto never asserts that a water source is definitely safe or unsafe
• Sroto does not identify individual people or households in results
• Always arrange for water testing by public health authorities
• Always seek prompt evaluation from a healthcare worker for anyone who is unwell

All computations occur directly on device. Sroto operates without network access, using optical screen codes or shared files for in person community collaboration.

The name Sroto (স্রোত) means "current" or "stream" in Bengali.