New Environment Agency data shows a sharp drop in storm overflow spills across England in 2025. Campaigners say the headline number is misleading — and the underlying data backs them up: just 0.5% of England's storm overflows saw a completed capital improvement last year. The real AMP8 storm overflow spend is only now reaching the market. Here's where it's landing, and who's already been appointed to deliver it.
On 26 March 2026, the Environment Agency published its annual Event Duration Monitoring (EDM) return — the statutory dataset that records every storm overflow discharge across England. The headline was a good one for water companies: 291,492 spill events in 2025, down 35% on 2024, with total spill duration down 48% and the average number of spills per overflow falling from 31.8 to 20.5. For the first time, every single storm overflow in England now has a monitor fitted, giving the most complete national picture yet of what's actually happening in the network.
It's the kind of number that gets repeated as evidence AMP8 investment is working. It isn't — not yet. Almost all of the improvement is weather, not infrastructure, and the same dataset shows exactly how little capital delivery has actually landed so far. For suppliers and contractors watching this sector for where the real work — and the real money — is going, that gap matters more than the headline figure.
2025 was significantly drier than 2024 across large parts of England, and storm overflows are only permitted to discharge during genuine rainfall or snowmelt events — fewer wet weeks mechanically means fewer spills. EA Chair Alan Lovell was candid about this in the agency's own release: "while these numbers are heavily influenced by rainfall levels in 2025, substantial reductions in spill duration and events are a clear win for people and the environment." Individual company figures make the weather link explicit — Anglian Water's East of England spill duration fell more than 80% year-on-year, and even South West Water, which saw significantly higher rainfall than the rest of England, still managed a 17% cut through operational improvements alone.
The Rivers Trust published its own analysis of the same EDM dataset five days later, and it's a useful corrective for anyone reading the headline number as evidence AMP8 is delivering. Their finding: just 79 overflows — 0.5% of all overflows in England — saw a completed regulation-led (capital) improvement in 2025. The vast majority of 2025's activity was investigations, not construction: the total number of storm overflows under investigation rose 65% year-on-year to 15,742, driven partly by tighter thresholds introduced under the 2025 Storm Overflow Assessment Framework — but only 37% of those investigations were actually completed during the year.
The EDM return separates "operational" improvements (staffing, maintenance, screen cleaning, emergency response procedures) from "regulation-led" or capital improvements (actual infrastructure — storage, treatment, network upgrades). Severn Trent and Wessex Water led the sector on completed operational improvements, at 31% and 33% of their overflows respectively — genuinely useful, but not the multi-billion-pound capital works AMP8 bills are funding. Thames Water and Northumbrian Water reported zero capital improvements — ongoing or complete — anywhere in their networks in 2025.
The Rivers Trust's own conclusion is blunt: AMP8 capital investment in storm overflows "has yet to start" in any meaningful sense. Actual construction is expected to begin moving through 2026, but even on the most optimistic current schedule, only 29 storm overflow improvements across the whole of England and Wales have an expected completion date within the first quarter of 2026. In other words: the spill numbers looked better in 2025 almost entirely because it rained less — not because the £10bn+ of AMP8 storm overflow investment has started showing up in the rivers yet.
A growing number of public tools — the Environment Agency's own EDM Data Portal, the Water UK-backed National Storm Overflow Hub, and independent sites like Sewage Map, WaterWatch and Top of the Poops — now let anyone check spill activity at a named river, beach or postcode in near real time. They're genuinely useful for transparency. None of them show who is actually being appointed to fix the problem, or when. That's the gap the rest of this article closes.
If capital delivery is only just starting, the frameworks and alliance appointments being made right now are the clearest signal of where 2026–2030 storm overflow spend will actually land — and which contractors are already positioned to win the sub-contract and supply chain work beneath them.
None of this is a reason to discount 2025's spill reduction — fewer discharges is a genuinely better outcome for rivers, whatever caused it. But for suppliers reading the sector's investment signals, the practical takeaway is that the capital delivery window is only just opening, not closing.
Anglian Water's £1.8bn Major Projects Framework standstill period runs to 26 August 2026, with contracts signable from 27 August — meaning the two winning D&C partners will start mobilising sub-contractor and specialist supply chains almost immediately on £400m+ of live coastal storm-spill schemes. If you're a specialist civils, MEICA or process technology contractor without a direct route into Anglian's programme, this is the moment to be talking to whichever partners are named.
Both Anglian's framework and Yorkshire's Storm Overflow Alliance explicitly reference building a wider supply chain ecosystem beneath the named Tier 1 partners — not just delivering everything in-house. Alliance and framework models like these are usually where smaller specialist firms get their entry point into AMP8 work, rather than through direct water company tenders.
Naming a small panel of preferred suppliers for a single product category — as Severn Trent has done with precast storm tanks — is a repeatable procurement model. Expect other water companies to run similar exercises for storage, screening and process equipment as AMP8 capital delivery ramps up through 2026 and 2027.
Water companies that reported zero capital improvements in 2025 — Thames Water and Northumbrian Water among them — are under real pressure to show construction progress, not just monitoring and investigation activity, in the next reporting cycle. That pressure tends to translate into faster procurement decisions once schemes are ready to go to market.
Water Industry Hub tracks framework awards, alliance appointments and procurement pipeline notices across every major UK water operator — and sends the ones that matter direct to Silver members every week. Don't wait for the standstill period to end before you start the conversation.
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