WaterWatch — Thames Water CSO Discharge Monitor

WaterWatch

Status About Contact Dashboard Account View map →

Now live — Thames Water region · updated every 15 min

Live data on

When a sewer overflows into your river, you deserve to know about it. WaterWatch puts real‑time discharge data from every Thames Water CSO site into plain sight — when it started, how long it ran, and exactly where on the map.

View the live map →Get alerts Open dashboard

Scroll

Quick views

Jump straight into the live tools — dashboard, rankings, map, and status.

📊

Network dashboard

Live discharges, offline monitors and network trend in one place.

🏆

Site rankings

See the worst CSO sites by spill hours and events.

🗺️

Live map

Every monitored site plotted with live discharge status.

✅

System status

Independent status page for API, portal, alerts and data quality.

New2025 annual discharge data is now available · View rankings →

·Read our latest blog post · How we measure improvement →

—

Sites discharging now

—

Network uptime

—

Monitors offline

Thames CSO sites monitored

Why we exist

Environmental data that belongs to everyone.

Discharge records from every Thames Water CSO site are publicly available — reported through an official EDM sensor network, updated every 15 minutes. WaterWatch makes that data actually usable.

Real-time alerts. Site histories. River-level context. Weekly summaries. Every number comes from the source, presented clearly. Independent, transparent, and free for everyone.

Our story →Read the blog →

“The rivers belong to everyone. So does the information about what's going into them.”

WaterWatch

The platform

Track every discharge.

Every CSO site in the Thames Water network — mapped, measured, and updated every 15 minutes from official EDM sensor data. Free and independent.

🗺️

Live discharge map

Every active overflow plotted in real time from Thames Water EDM sensors, refreshed every 15 minutes.

📊

Per-site discharge history

Full event records for any site — start time, duration, and cumulative spill hours by month and year.

🔔

Instant email alerts

Get notified the moment a discharge starts or stops at a site you follow. Free, no spam.

📥

CSV data export

Download raw discharge data for any site or date range for your own research.

Live discharges, offline monitors and year-on-year trends across the entire network in one view.

Every Thames Water CSO site ranked by total spill hours and event count. Sort by year or river.

Clear colour-coded signal for every site: improving, worsening, or flat — backed by actual data.

Get the numbers — worst sites, most-impacted rivers, total spill hours, and rainfall context.

Explore →

Live

🌧️

River & rainfall context

Live EA river levels and rainfall readings paired with every discharge event.

Explore →

How it works

From sensor to your inbox in minutes.

01

🏭

Sensor records it

EDM sensors at each CSO site record when discharge starts and stops, reporting to the official network every 15 minutes.

02

⚡

We ingest it

WaterWatch pulls the latest readings continuously and detects the moment a site transitions to discharging.

03

🗺️

Map updates live

The discharge map reflects the current state of every monitored site in real time — no refresh needed.

04

🔔

You get notified

If you're subscribed to a site, we fire an alert the moment we detect it starts or stops discharging.

From the blog

Transparency in practice

All posts →

Methodology16 Mar 2026 · 10 min read

How we determine if a CSO site is improving

Reducing spill hours year-on-year sounds straightforward. It isn't. Rainfall, sensor gaps, and three-year baselines all complicate the picture. Here's our honest framework for reading improvement signals.

Read →

Transparency15 Mar 2026 · 8 min read

Why you can trust what WaterWatch tells you

Every number on WaterWatch comes from Thames Water's own EDM sensor network. We don't estimate, extrapolate, or fill gaps. Here's exactly how our pipeline works — and where its limits honestly lie.

Read →

Built by people who give a damn

WaterWatch is an independent project. No investor pressure, no corporate agenda — just a belief that environmental data should be genuinely accessible.

Newsletter

Stay informed. We're live.

Subscribe to the WaterWatch newsletter and get spill roundups, platform updates, and the numbers behind Thames Water's overflow network — straight to your inbox.

Free forever · No spam · Unsubscribe any time