Methodology & Data Sources

Where the Data Comes From

All the core data on this site comes directly from the Brihanmumbai Municipal Corporation (BMC). Specifically, the BMC's Hydraulic Engineer's Department, located at the Bhandup Complex, publishes a comprehensive daily water stock report. This report is typically released every morning around 6:00 AM IST and reflects the water levels recorded early that same morning.

What We Track

For each of the seven lakes, the daily report provides several key fields that we mirror:

• Stored ML: The current usable volume of water in Million Litres.
• Level (m): The current height of the water surface.
• Rainfall: Both the past 24-hour rainfall and the total rainfall accumulated this monsoon season.
• Remarks: Any notes from the engineers, such as when a lake starts overflowing.

How We Calculate Derived Numbers

While the BMC provides raw numbers, we calculate a few derived metrics to make the dashboard easier to read at a glance:

• Percentage Full: We divide the total currently stored water by the total maximum capacity of all seven lakes (14,47,363 ML).
• Day-on-Day Change: We subtract yesterday's total stored volume and percentage from today's report to show whether levels are rising or falling.
• Days of Water Left: We take the current total stock and divide it by Mumbai's estimated average daily demand of ~3,950 MLD. This is a rough, straight-line estimate. It assumes demand stays constant and does not account for evaporation or ongoing monsoon inflows that constantly add to the supply.
• Yearly Comparison: We compare today's percentage against the same calendar date from previous years, pulling from our historical archive of BMC reports.

Limitations

We strive to present the data exactly as the BMC publishes it, without editorializing the numbers. However, because we mirror human-generated reports, occasional transcription discrepancies or delayed reports from the BMC can happen.

If a daily report is delayed, our site will clearly label the data as pending and show the most recent available date. The official word on water levels, shortages, or cuts is always the BMC's. This dashboard is built for public convenience, but it is not a substitute for official municipal announcements.