Ofwat WIRI guidance for reporting and assessing incidents

Ofwat's Guidance for reporting and assessing Water Industry Regulation Incidents (WIRI) matters because it shapes how water and wastewater companies identify, evidence, classify, and report incidents that could impact customers, the environment, and service reliability. If you manage spill response, pollution prevention, or environmental compliance in a water utility or contractor setting, understanding WIRI helps you answer a critical operational question: what do we need to do right now, and what proof will we need later, if an incident occurs?

Question: What is WIRI and why should my team care?

Solution: Treat WIRI as a practical incident reporting and assessment framework used in the UK water industry. It influences how incidents are evaluated and how performance and outcomes are scrutinised. In real terms, WIRI pushes sites to:

• Detect incidents early and reduce severity through fast containment.
• Record clear facts and actions taken, including timelines.
• Demonstrate reasonable steps to prevent pollution and service harm.
• Show robust governance around environmental incidents and near misses.

For spill control and compliance teams, that means your spill kits, drain protection, bunding, and response procedures are not just operational tools - they are evidence of preparedness and competent response.

Question: What types of incidents could fall under WIRI?

Solution: WIRI commonly relates to incidents that may impact customers, service, water quality, wastewater operations, and the environment. While your internal teams will apply the detailed definitions, a spill management view is that WIRI risk often increases when there is:

• Loss of containment of oils, fuels, treatment chemicals, sewage, or trade effluent.
• Pollution risk to surface water or groundwater, especially via gullies, drains, and outfalls.
• Operational failures at pumping stations, treatment works, tank farms, chemical dosing areas, or generator/plant refuelling locations.
• Repeat events or near misses indicating weak control measures.

If your site has tanks, IBCs, drums, transfer hoses, sumps, interceptors, or any chemical delivery and decanting activity, the practical assumption should be: if it can reach a drain, it can become a reportable incident if controls fail.

Question: What should we do immediately when an incident happens to support WIRI reporting?

Solution: Use a simple, repeatable spill response workflow that protects people, contains the release, protects drainage, and captures evidence. A WIRI-ready response typically includes:

1. Make safe - stop work, isolate ignition sources if flammable, use appropriate PPE, and assess hazards (for example chlorine-based chemicals or hydrocarbons).
2. Stop the source - close valves, uprighting containers, isolate pumps, or deploy temporary leak control as competent to do so.
3. Contain fast - deploy absorbent socks, booms, and pads to prevent spread across hardstanding and to keep liquid away from thresholds, kerbs, and gullies.
4. Protect drains - use drain covers, drain mats, pipe blockers, or sand/absorbent barriers where suitable to prevent entry into the drainage system.
5. Recover and clean - use suitable absorbents for oils, chemicals, or general purpose fluids, then containerise waste for compliant disposal.
6. Record the timeline - time discovered, time contained, time drain protected, who attended, what products used, and what volumes were estimated.

This approach supports both good environmental outcomes and robust incident documentation. For spill response equipment and utility-specific applications, see spill management for water utilities.

Question: What evidence do we need to keep for WIRI assessment?

Solution: Plan to collect evidence that demonstrates (a) what happened, (b) what was at risk, (c) what you did, and (d) what you will do to prevent recurrence. Useful evidence typically includes:

• Photographs of the source, the extent of spread, nearby drains, and deployed controls (drain covers, booms, bunds).
• Volume estimates (best estimate), product identity (SDS), and location details.
• Drainage pathway notes: is it foul, surface, combined, or to an interceptor? Where does it discharge?
• Response actions: containment time, equipment used, contractor call-out if required.
• Waste documentation: packaging of used absorbents and disposal route.
• Corrective actions: repairs, procedural changes, training, inspections.

Sites that already use formal spill kits, drip trays, and bunding can show that controls were in place before the incident, not improvised after it.

Question: How do spill kits and drain protection reduce WIRI severity?

Solution: WIRI severity can be influenced by the scale of impact and the effectiveness of mitigation. Spill control equipment reduces harm by shortening the time between discovery and containment. Practical examples:

• Chemical dosing area: a hose coupling fails during transfer. A nearby chemical spill kit and a bunded area limit spread, while drain protection prevents entry to surface water drains.
• Generator refuelling: diesel splash and drip losses are captured using a drip tray and oil absorbents, reducing the risk of hydrocarbons reaching a gully.
• Pumping station: oily water escapes from maintenance activity. Absorbent booms contain the fluid at the threshold and protect the drainage route.

If you need to standardise spill response across multiple sites, ensure spill kits are matched to the fluids present (oil-only vs chemical vs general purpose), the likely spill size, and the proximity to drains and watercourses.

Question: What prevention controls should we review to strengthen compliance?

Solution: Prevention is a core part of demonstrating competent environmental management. WIRI-relevant controls commonly include:

• Bunding and secondary containment for tanks, IBCs, and chemical storage areas, sized and maintained for realistic failure scenarios.
• Drip trays for decanting, dosing, and maintenance tasks where small, frequent losses occur.
• Drain protection (covers, blockers, shut-off devices) for high-risk areas and delivery points.
• Inspections and housekeeping to reduce corrosion, overfills, and hose failures.
• Training and drills so staff can deploy spill kits and drain covers quickly and safely.

Even where the initial release is small, poor drainage awareness and delayed response can escalate environmental impact and reporting consequences.

Question: How do we choose the right equipment for a WIRI-ready site?

Solution: Build an equipment plan around credible scenarios and site layout. A strong minimum approach is:

• Spill kits located at chemical stores, refuelling points, pump rooms, and areas with drains.
• Drain protection positioned where staff can deploy it in seconds, not minutes.
• Absorbents matched to fluids: oil-only for hydrocarbons; chemical absorbents for acids/alkalis; general purpose for water-based fluids.
• Clear signage and simple instructions inside kit lids to reduce decision time during an incident.

For water sector spill response planning and product selection considerations, refer to Serpro guidance for water utilities.

Question: Where can I read the official WIRI guidance?

Solution: Use the official source for definitions, thresholds, and reporting expectations: Ofwat publishes regulatory guidance and updates, including WIRI-related materials. Always check the latest version and align your internal procedures, incident forms, and escalation routes accordingly.

Question: What is a practical next step for improving readiness?

Solution: Run a short site-based spill and drain pathway review:

• Walk the site and map which gullies and drains connect to surface water, foul, combined, or an interceptor.
• Identify top 5 credible spill points (chemical deliveries, IBC/tank valves, refuelling, dosing skids, maintenance bays).
• Place spill kits and drain covers at those points and verify access is always clear.
• Test response time with a drill and update your incident record template to capture WIRI-relevant evidence.

This connects spill management controls directly to incident reporting quality, environmental protection, and operational resilience.

Related information: Spill management and spill kits for water utilities.

Citations: Ofwat - UK water sector economic regulator.