WaterWatch Blog

Data, transparency, and the odd rant
about sewage.

Methodology deep-dives, data journalism, and the occasional opinion piece from the team building WaterWatch. No spin. No paywall. Just the data.

Published
Methodology

We built an AI to predict sewage spills. Here's exactly how it works.

WaterWatch doesn't just track spills that already happened. It now models the conditions that make them likely. Antecedent wetness, catchment runoff, per-site logistic regression, and a metric that tells you how many millimetres of rain stand between a site and its next discharge.

DW
Daniel Walls
Founder, WaterWatch
3 Apr 2026·12 min readRead article
Methodology

Spills are bad. But how bad? How we measure the real impact on your river.

Counting spill hours tells you how often a CSO discharged. It doesn't tell you whether the river actually noticed. We cross-referenced 77,000 discharge episodes against EA water quality samples — here's what we found, and how we turned it into a 0–100 impact score.

DW
Daniel Walls
Founder, WaterWatch
3 Apr 2026·10 min readRead article
Transparency

The role of ads in WaterWatch

A 17-year-old's completely honest, only slightly embarrassing explanation of why WaterWatch has ads, where they live, and why this particular page has quite a lot of them. AWS credits expire. Servers don't pay for themselves. Here's the deal.

DW
Daniel Walls
Founder, WaterWatch
31 Mar 2026·6 min readRead article
Methodology

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.

DW
Daniel Walls
Founder, WaterWatch
16 Mar 2026·10 min readRead article
Transparency

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.

DW
Daniel Walls
Founder, WaterWatch
15 Mar 2026·8 min readRead article
Coming soon
Data
How Event Duration Monitoring actually works
Coming soon
Policy
What the Storm Overflow Discharge Reduction Plan means in practice
Coming soon
Methodology
Reading a CSO site page: a guide for journalists and researchers
Coming soon
Analysis
Yorkshire Water, Southern Water and beyond: expanding the map
Coming soon