Spill Control for Utilities and Water Industry — Operational Compliance
Utility companies — water, electricity, gas, and telecommunications — operate some of the UK's most complex chemical storage and handling environments. This guide covers the specific spill control obligations for water treatment works, electricity substations, gas networks, and utility infrastructure, including relevant regulatory frameworks and practical compliance measures.
Water Treatment Works — Chemical Dosing
Water treatment works use significant quantities of chemicals for purification and disinfection. Key chemicals and their secondary containment requirements:
| Chemical | Use | COSHH Classification | Containment Requirement |
|---|---|---|---|
| Sodium hypochlorite (12.5%) | Disinfection | H314, H400, H410 | HDPE/PP bund, corrosion resistant |
| Ferric sulphate | Coagulation | H302, H318 | 110% sump, impermeable bund |
| Aluminium sulphate | Coagulation/flocculation | H318 | Secondary containment, drain sealed |
| Chlorine gas (cylinders) | Disinfection (older works) | H270, H314, H400 — COMAH Schedule 1 | Specialist containment room, scrubber |
Electricity Substations — Transformer Oil
Large power transformers contain 10,000–100,000 litres of dielectric mineral oil. A transformer oil release is a significant environmental incident — the oil is classified as WGK 2 (clearly hazardous to water) and can contaminate groundwater rapidly. Requirements: secondary containment sized for 110% of transformer oil volume; interceptor drain systems; oil-only spill kits positioned adjacent to all large transformers; monthly bund inspection records. Legacy transformers pre-1987 may contain PCB-containing oils — specialist disposal contractors required.
Gas Network — Odourant Storage
Natural gas is odourised with mercaptan compounds (typically THT — tetrahydrothiophene). Mercaptan is toxic, flammable (H225), and has an extremely low odour threshold (detectable at 0.0005 ppm). Storage: DSEAR-compliant secondary containment, explosive atmosphere classified area around storage tanks, specialist chemical spill kits for mercaptan response (neutralisation with oxidising agent required).
Regulatory Framework for Utilities
Utility sites operate under multiple overlapping frameworks: COSHH 2002 for workplace chemical exposure; EPR 2016 for environmental permitting; WRA 1991 for water pollution; DSEAR 2002 for flammable/explosive substances; COMAH 2015 if threshold quantities are exceeded (common for chlorine gas and sodium hypochlorite at water works).
Last reviewed: April 2026 | Need expert advice? Call 01744 520 110