London’s Super Sewer Hits Full Capacity: Tideway’s Annual Report Highlights Major Milestones

Bazalgette Finance PLC annual report: Tideway reaches full capacity in a milestone year

This RNS is, on the face of it, a routine annual report publication notice. But the substance matters. Bazalgette Finance plc has published the annual report and financial statements for the year ended 31 March 2026, alongside reports for Bazalgette Holdings Limited and Bazalgette Tunnel Limited, which trades as Tideway.

The big takeaway is that London’s Thames Tideway Tunnel, better known as the super sewer, has now begun operating at full capacity. For investors, that is the real story here. It signals a shift from building a massive piece of infrastructure to running it over the long term.

Key numbers from the Tideway annual report RNS

Metric	Figure	Why it matters
Reporting period	Year ended 31 March 2026	Sets the latest annual reporting point
Tunnel length	25km	Shows the scale of the asset now in operation
First connection made	August 2024	Marks when the system started intercepting sewage
Storm sewage intercepted	More than 20 million tonnes	Evidence the asset is doing its job in the real world
Customer bill impact	Within the £20-£25 range	Suggests cost discipline remains intact
Public spaces created	13	Highlights the wider regeneration legacy
New CEO	Matt Parr, from May 2026	Leadership is changing as the project enters a new phase

Why Tideway operating at full capacity matters for Bazalgette Finance investors

For any big infrastructure project, construction is usually the risky bit. Costs can drift, deadlines can slip, and the final asset still has to prove it works. So when Tideway says the system is now operating at full capacity, that is a meaningful reduction in project risk.

In plain English, this is the point where the tunnel stops being mostly a promise and becomes a working asset. That tends to be a healthier position for any financing structure sitting behind it, because the operational story is usually steadier than the construction story.

That said, the company is careful not to say the job is completely done. Matt Parr says the focus remains on safely completing the remaining work and ensuring the tunnel performs reliably. That tells you this is a major milestone, not the final full stop.

London super sewer performance: more than 20 million tonnes of sewage intercepted

This is the standout operating statistic in the RNS. Since the first connection in August 2024, the 25km tunnel system has intercepted more than 20 million tonnes of storm sewage that would otherwise have entered the River Thames.

That matters because it shows immediate practical use, not just engineering progress. Investors and the public can see a direct environmental outcome from the project, which is exactly what Tideway was built to deliver.

There is also a reputational angle here. Projects like this are expensive and highly visible, so they need to demonstrate public value. Preventing sewage pollution on this scale is a strong defence against criticism that the scheme is all cost and no benefit.

Tideway costs and Thames Water bill-payers: a positive sign on budget discipline

One of the more reassuring lines in the RNS is that the cost to Thames Water bill-payers remains within the £20-£25 range outlined at the outset of the project, in 2014/15 prices. That is a clear positive.

Why? Because investors hate nasty surprises, and regulated infrastructure projects live or die on confidence in cost control. If the customer impact is still within the original range, it supports the idea that Tideway has remained financially disciplined while delivering a very large and complicated build.

There is a limit to how much we can infer from the RNS alone, though. It does not disclose a fresh total project cost figure here, and it does not provide detailed financial metrics in the announcement itself. So the message is positive, but not complete.

Matt Parr becomes CEO as Tideway moves from construction to long-term operation

This annual report is also the first under new Chief Executive Officer Matt Parr, who succeeded Andy Mitchell in May 2026 after more than a decade leading the project. Leadership changes can sometimes unsettle investors, but in this case the timing makes sense.

The project is transitioning from build mode to operating mode. Those are different jobs. One is about delivery and construction management; the other is about reliability, safety, maintenance and long-term performance.

That does not remove risk entirely. Any handover at this stage needs careful execution, especially for an asset of national importance. But it looks more like an orderly baton pass than a sudden reset, which is the better outcome.

Tideway’s wider legacy: 13 new public spaces and environmental improvements

The RNS also highlights the broader legacy of the programme, including 13 new public spaces along the River Thames and new habitat areas. This is not the kind of line that usually drives a financing case on its own, but it does matter.

Large infrastructure schemes increasingly need to show they leave something behind beyond the core engineering. Public spaces, environmental improvements and skills development all strengthen the project’s social licence to operate. For an asset tied closely to public policy and public bills, that is useful.

What the Bazalgette Finance RNS does not disclose

Here is the important caveat. This RNS is not a full trading update. It tells investors that the annual reports have been published and pulls out a handful of milestone highlights, but it does not give the full financial picture in the announcement text.

So if you are looking for revenue, profit, debt, cash flow, financing costs, covenant details or distributions, those are not disclosed in the RNS itself. You would need to go into the published annual report and financial statements for that level of detail.

That is worth stressing because the name of the issuer is Bazalgette Finance plc. For anyone following the credit quality or funding structure, the operational progress is encouraging, but the hard financial detail still sits in the accounts rather than this short notice.

Bazalgette Finance PLC verdict: a quietly strong update with one obvious next step

My read is that this is a good-news RNS, even if it is dressed up as a routine document publication. The Thames Tideway Tunnel has hit full capacity, more than 20 million tonnes of sewage have been intercepted, and the bill impact remains within the original £20-£25 range in 2014/15 prices. That is a solid set of milestones.

The biggest positive is de-risking. Tideway is moving out of the heaviest construction phase and into long-term operation, which is usually where infrastructure stories become steadier and easier to assess. The biggest negative is simply that the RNS itself is light on financial detail, so investors still need to read the annual report before making a fuller judgement.

Put simply, the project appears to be doing what it was built to do, and doing it without blowing the customer cost range flagged at the outset. For Bazalgette Finance plc, that is the kind of progress you want to see.