Blog · CityWatch
A silent pump is not a running pump: why “no data” must show up on the map.
The most dangerous status in a city control room is the one nobody displays: the sensor that has stopped talking and is assumed to be fine.
The status nobody shows
Most city dashboards have two colours for a pump: running or not running. In practice there is a third state that matters more than either. The pump has not reported anything for an hour. Perhaps it is running. Perhaps the power failed, the panel tripped or the telemetry unit lost its connection. On a dashboard with two colours, that pump is usually drawn as running, because that was its last known state.
The same happens with rain gauges and channel level sensors. A gauge that stops sending readings during heavy rain looks exactly like a gauge reporting no rain. The quiet sensor and the dry sensor are indistinguishable unless the system is designed to tell them apart.
Why silence is worse than a fault
A pump marked offline gets attention. Someone is sent, a standby set is moved, the ward is warned. A pump that is silently assumed to be running gets nothing, until the water rises in the low-lying ward it was meant to protect. The early warning depends on the same inputs: if the rain rate or the channel trend is missing, the alert threshold is never crossed, and the warning window passes without anyone noticing that the system was blind.
| What the map shows | What the control room does | Risk |
|---|---|---|
| Running | Nothing; it is handled | Low, if the data is fresh |
| Offline | Sends a crew or a standby | Visible and managed |
| No telemetry, shown as running | Nothing | High, and invisible |
| No telemetry, shown as no telemetry | Calls the operator, sends a check | Visible and managed |
Our rule: never assume
In CityWatch pumps are shown as running, offline or "no telemetry", never assumed. Silent sensors are flagged at the point the data streams in, before they reach the alert rules or the map. It is a small design choice with a large effect: it turns an invisible risk into a visible task.
The same principle runs through the rest of the tower. A complaint becomes a ticket with an owner, not a note in a register. A desilting claim needs a geotagged before-and-after photo for that drain segment. A pump run is a reading, not a statement. The common idea is that the system should say "we do not know" out loud whenever that is true.
What a city can do before the next monsoon
Most of this does not need new equipment. It needs a different attitude to the data already flowing in.
- Add a third colour. Every pump and gauge on the map should be able to show "no telemetry", with the time of its last reading.
- Set a freshness rule. Decide how long a sensor can be silent before it is flagged, and make that shorter during heavy rain.
- Give silence an owner. A flagged sensor should create a task, like a complaint does, so someone checks it.
- Count blind spots. Before the season, list the wards where a single silent gauge would leave the alert rules blind.
- Review it after every storm. In the replay, mark every period when a sensor was silent and ask what the alert would have said with it.
Our monsoon preparedness checklist includes sensor checks alongside the drains and pumps themselves, and our guide to how an urban flood early warning system works explains why the alert depends on rain rate and channel trend together.
Honest data builds trust
It can feel uncomfortable to show a commissioner a map with grey "no telemetry" markers on it. It looks less finished than a map that is all green. But a map that is all green while a pump is down is the one that does real damage, to the ward and to the control room's credibility. We would rather show the gap and close it. More in the CityWatch guides.
Questions
What does no telemetry mean for a pump?
The pump has stopped sending data. It may be running or it may have failed; the control room does not know, and should treat it as a task to check rather than assume it is running.
Why does a silent rain gauge matter for flood warnings?
A gauge that stops reporting looks like a gauge recording no rain, so the alert threshold may never be crossed. Silent sensors should be flagged before they reach the alert rules.
How can a city reduce sensor blind spots?
Show a no-telemetry state on the map, set a freshness rule, give each flagged sensor an owner, and list wards that depend on a single gauge.
See it on your own data. CityWatch — Warn before the street floods. Book a 30-minute working session with an engineer.