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Thames Water: Performance Report
Rank #14 of 19 UK water companies · GWSS 62.7/100 (Average) · Leakage 143 l/p/d · Interruptions 00:09:35/property · CRI 2.04 (Ofwat APR 2024-25 / DWI 2024)
How does Thames Water perform compared to other UK water companies?
In Ofwat APR 2024-25 / DWI 2024, Thames Water ranks #14 of 19 UK water companies with a Gera Water Service Score (GWSS) of 62.7/100 — Average, 8.1 points below the national median of 70.8/100. Key metrics: leakage 143 l/p/d, supply interruptions 00:09:35/property, Compliance Risk Index 2.04 (Ofwat APR / DWI 2024, OGL v3.0).
Leakage score
25/100
143 l/p/d
E&W avg: 109
▲ above avg · weight 40%
Interruptions score
94.3/100
00:09:35
E&W avg: 22 mins
▼ below avg · weight 30%
Water quality score
81.3/100
CRI 2.04
E&W avg: 3.72
▼ below avg · weight 30%
Thames Water performance figures (Ofwat APR 2024-25 / DWI 2024)
| Measure | Value | vs England & Wales |
|---|---|---|
| Gera Water Service Score (GWSS) | 62.7/100 | Average (grade C) |
| Overall rank | #14 of 19 | vs national median GWSS 70.8/100 |
| Leakage | 143 l/p/d | ▲ above E&W avg 109 l/p/d |
| Supply interruptions | 00:09:35 | ▼ below E&W avg 22 mins |
| CRI (water quality) | 2.04 | ▼ below E&W avg CRI 3.72 |
| Region | London & South | Ofwat regulatory area |
Thames Water CRI trend (2021–2024)
Compliance Risk Index (lower = better). Source: Drinking Water Inspectorate (DWI) via DiscoverWater.co.uk.
| Year | CRI | vs E&W avg (3.72) |
|---|---|---|
| 2024 | 2.04 | ▼ below avg |
| 2023 | 10.96 | ▲ above avg |
| 2022 | 1.43 | ▼ below avg |
| 2021 | 2.04 | ▼ below avg |
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Frequently asked questions
- What is Thames Water's GWSS score?
- Thames Water scores 62.7/100 on the Gera Water Service Score (GWSS) in 2024-25 — Average (grade C), ranking #14 of 19 UK water companies. The score combines leakage (143 l/p/d, weight 40%), supply interruptions (9 mins, weight 30%), and water quality CRI (2.04, weight 30%) from Ofwat APR 2024-25 and DWI data.
- How much water does Thames Water leak?
- Thames Water lost 143 litres of water per property per day through leaks in 2024-25, above the England and Wales average of 109 l/p/d. Source: Ofwat Annual Performance Report 2024-25, via DiscoverWater.co.uk (OGL v3.0).
- How often does Thames Water cause supply interruptions?
- In 2024-25, Thames Water customers experienced an average of 00:09:35 of lost water supply per property from interruptions lasting 3+ hours — better than the national average of 22 mins. Source: Ofwat APR 2024-25 via DiscoverWater.co.uk.
- What is Thames Water's Compliance Risk Index (CRI)?
- Thames Water's CRI in 2024 was 2.04, below the England and Wales average of 3.72. The CRI measures overall performance against national drinking water quality standards (lower = fewer compliance failures). Source: Drinking Water Inspectorate (DWI), Jan–Dec 2024, via DiscoverWater.co.uk.
- How has Thames Water's water quality changed over the past 4 years?
- Thames Water's CRI (Compliance Risk Index) over the past 4 years: 2024: 2.04, 2023: 10.96, 2022: 1.43, 2021: 2.04. Lower CRI = fewer quality compliance failures. Source: Drinking Water Inspectorate (DWI), via DiscoverWater.co.uk.
Contains public sector information published by Ofwat / Drinking Water Inspectorate and licensed under the Open Government Licence v3.0. Source: Ofwat APR 2024-25 + DWI CRI 2024 (via DiscoverWater.co.uk) (Ofwat APR 2024-25 / DWI 2024, published June 2026 (Ofwat APR 2024-25)).