Safe Urban Bathing in Berlin
Urban rivers are dynamic systems. Water quality can change within minutes, especially after rainfall. Our platform provides a real-time assessment of bathing conditions by combining continuous sensor measurements with hydrological data and intelligent interpretation. The goal is simple: make complex water quality processes visible and understandable, and translate them into a clear bathing recommendation. [Work in progress - last modification 06.05.2026]
How the System Works
Instead of relying on a single parameter, the system evaluates patterns across multiple signals. Different processes leave different signatures in the water:
- Rainfall changes flow and transport conditions
- Combined sewer overflows introduce microbial contamination
- Urban runoff alters turbidity and organic matter
By continuously measuring and combining these signals, the system can detect:
- when an event occurs
- whether it is hygienically relevant
- and how it evolves over time
What You See and How to Read
The interface is structured as a sequence of time-synchronized Grafana panels with live data. This allows you to follow system behavior directly across panels. The text below acts as a guide.
To access the hygienic relevance the systems check if rainfall gets strong and what the current flow conditions are. If now water quality signals react (Panels 2, 3.1, 3.2) microbial indicators might rise or remain stable (Panels 2)
Only by combining these observations can the system distinguish between harmless fluctuations and events that affect bathing safety. The system internally compares upstream and downstream measurements and accounts for flow-dependent travel time, even though this is not shown as a dedicated panel.
Above: Map 1 – Hydrological conditions and distribution of measurement points
The map above and the graph here display the flow in Spree & Landwehrkanal, the flow time in the Vorstadt and Mitte and rainfall in the part of Berlin that influences the Spree. To get a spatial overview also the positions of the we4water sensor stations and the senate sampling points are marked.
These hydrological boundary conditions are showing the current system state and potential triggers. They give insides about the last rainfall, if it is likely to influence the quality and how fast water (and potential pollution) is moving through this part of Berlin.
Hygienic sensor parameters - Proteus probe
This panel displays turbidity, fluorescence signals, estimated E. coli, estimated coliform bacteria, and water temperature. Discrete laboratory samples (E. coli and coliform bacteria) are shown as individual data points when available.
These parameters form the core signal set for real-time hygienic assessment. They are the most relevant sensor signals for bathing safety. They visualize whether the water carries signs of fresh contamination, ow strong and how dynamic the hygienic signal is and how sensor-based estimates relate to the available laboratory reference points.
Interpretation note: The underlying sensor system (Proteus; currently measuring but not yet online) detects microbial activity in a non-specific way. Therefore the calibration is performed for both E. coli and coliform bacteria. Coliform bacteria often provide a more stable and robust signal due to higher concentrations. This is the key layer for assessing bathing suitability in real time.
Quality assurance note: Laboratory samples of the Berlin Senate are available at monthly frequency and with time delay. They are therefore used primarily for calibration and validation over longer periods.
Panel 3.1 – Nutrients, Ionic Signals and suspended solids (last 7 days, live)
This panel displays ammonium and nitrate concentrations as well as conductivity and suspendes solids. These parameters help identify wastewater influence and system disturbance.
[Coming soon: 3.2 Grafana panel with parameters: UV absorption, TOC/DOC proxies, Chlorophyl-a ]
Panel 3.2 – Organic Matter Signals (last 7 days, live)
This panel shows UV absorption and organic matter proxies (TOC/DOC), which indicate organic load and potential contamination sources. Additionally Chlorophyl-a is displayed to show how big the algea fraction of the organic matter is and if potential algea blooms might become relevant.
This diagram provides insight into what kind of input is affecting the river: Is it consistent with a wastewater influence? How strongly is the water composition changing? Is an event rather caused by rainfall runoff, a combined sewer overflow or other background variation?
As soon as all required sensors are online the data is continuously evaluated and translated into a simple result:
🟢 Green — Suitable for bathing
No relevant anomalies detected. Conditions are stable.
🟡 Yellow — Limited suitability
The system detects changing conditions. Caution is advised.
🔴 Red — Not suitable for bathing
Strong indication of contamination, typically linked to rainfall events and wastewater inputs.
The end of the German Democratic Republic era lead to big changes in the industrial environment of Berlin. The implementation of newer environmental laws, closing of industrial facilities and other developments has significantly improved the water quality in Berlin since 1985. Its only since a few years the old barge operators in the historic say that they see the first time in their lives the bottom of their Spree.
Why This Approach Matters
Traditional water quality monitoring relies on infrequent sampling. This means short-term pollution events often go unnoticed. Our system closes this gap by:
using continuous sensor data directly visualized in Grafana panels integrating hydrological context into the same view validating signals using independent laboratory measurements (Panel 2.2) and interpreting combined signal patterns
This enables: early detection of pollution events/ transparent quality assurance through data comparison/ better understanding of urban water dynamics/ and safer, more transparent use of rivers for bathing
It is a continuously evolving data system as more data becomes available: models improve, signals become more reliable and the interpretation becomes more precise
Partners
TU Berlin, AGroLab Potsdam, Landeslabor Berlin Brandenburg, greentech.berlin e.V., Fluss Bad Berlin e.V., Spreevision.de
Get Involved
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