Pest Control Risk Assessment: Site Survey, Infestation Severity Scoring, Treatment Plan and Follow-Up Schedule

Summary

A risk assessment is not a form-filling exercise — it is the professional process that determines whether a treatment is safe to carry out, what products are appropriate, who might be at risk, and what follow-up is needed. In the pest control sector, this takes two distinct forms: a site survey and infestation severity assessment (what pest, how bad, where) and a COSHH assessment (what chemicals, what hazards, what controls). Both are required for professional work.

The site survey is the diagnostic phase. Pest controllers use it to confirm species, locate harbourage and entry points, assess infestation severity, and identify environmental constraints — vulnerable people on site, food preparation areas, proximity to drains, water courses, or sensitive habitats. Done properly, a site survey prevents treatment failures (treating symptoms not the source), protects the operative from legal liability, and gives the customer a clear written treatment plan.

Infestation severity scoring is less standardised than in some industries, but most professional frameworks use a three- or five-point scale to communicate urgency and guide treatment intensity. The British Pest Control Association (BPCA) and the National Pest Technicians Association (NPTA) both publish guidance on structured survey approaches. For commercial contracts (food businesses, healthcare, housing associations), a documented survey and treatment plan is a contractual requirement — and the customer may use it as evidence in regulatory inspections by the Food Standards Agency or local authority environmental health officers.

Key Facts

• COSHH Regulations 2002 — mandatory requirement for a written risk assessment before using any substance hazardous to health, including pesticides
• Health and Safety at Work etc. Act 1974 (Section 2) — general duty to ensure the safety of employees; risk assessment is the primary tool
• Management of Health and Safety at Work Regulations 1999 — requires a "suitable and sufficient" risk assessment for all work activities
• Control of Pesticides Regulations 1986 (as amended) — pesticides must be used "safely, effectively and humanely"
• BASIS PROMPT — the UK professional qualification scheme for pesticide users; most professional products require the holder or a supervised operative to hold this
• Site survey minimum scope — species identification, activity level, harbourage locations, entry points, environmental constraints
• Infestation severity: 3-point scale — Low (incidental, isolated signs), Medium (established, regular activity), High (severe, structural harbourage, health risk)
• Vulnerable people — children, elderly, immunocompromised, pregnant women, asthmatics; product selection and access restrictions must reflect their presence
• Food premises — higher scrutiny; only food-safe products approved for use in food areas may be used; Food Safety Act 1990 and Food Hygiene Regulations 2006 impose strict requirements on food business operators
• COSHH record retention — 5 years minimum for most hazardous substances
• Follow-up visit frequency — typically 7–14 days for rodents; 24–72 hours for wasps; 4–6 weeks for cockroaches (depending on treatment type)
• Treatment plan document — must name the pest, products to be used, application method, target areas, PPE, restrictions on access, and follow-up schedule
• Drainage survey — essential for rodent infestations in older properties; broken drains are a primary entry route for rats

Quick Reference Table

Detailed Guidance

Site Survey: The Diagnostic Phase

A site survey should be carried out before any treatment begins — even for a straightforward domestic wasp job. The survey has three goals: confirm the pest, assess severity, and identify constraints.

Species confirmation: Never assume. A customer reporting "mice" may have rats, squirrels, or even a bird nesting in the loft. Misidentification leads to wrong bait, wrong trap type, and wasted visits. Use droppings size, run width, gnaw marks, and behaviour to confirm species.

Activity mapping: Walk the full perimeter and interior. Mark on a site plan (even a sketch) where activity is found — runs, burrows, gnaw damage, droppings, smear marks, dead insects. This map becomes part of the treatment plan and the baseline for follow-up comparisons.

Harbourage and entry points: Identify where the pest is living and how it is getting in. For rodents, probe the perimeter of the building for gaps at DPC level, service entry points, and broken air bricks. For insects, look at roof voids, wall cavities, and damp timber. Entry points identified during the survey should be listed in proofing recommendations — treatment without proofing is a temporary fix only.

Environmental constraints: Record everything that affects product selection or application:

• Food preparation areas (restrict product options)
• Water courses or drains within 10 metres (affects rodenticide placement under CRRU Stewardship)
• Presence of children, elderly, pets, or vulnerable people
• Other non-target animals (bird feeders, livestock nearby)
• Heating systems (affects insecticide residue times)
• Confined spaces (see fumigation regulations)

COSHH Assessment: Product Hazards and Controls

Every pesticide product has a Safety Data Sheet (SDS) — formerly called a Material Safety Data Sheet (MSDS). The COSHH assessment is based on the SDS and the site-specific application context.

What to record in the COSHH assessment:

1. Product name and active ingredient
2. Hazard classification (from SDS Section 2)
3. Exposure route (inhalation, skin contact, ingestion)
4. Workplace Exposure Limit (WEL) if applicable (from HSE EH40)
5. Control measures — PPE, ventilation, restricted access
6. Emergency procedures (from SDS Section 4 and 6)
7. Disposal route (from SDS Section 13)

PPE selection: Match PPE to the SDS. A product requiring respiratory protection means a half-face respirator with appropriate filter cartridge — a dust mask is not sufficient. Keep PPE inspection records.

Access restrictions: After applying pesticide in a room, determine when people can safely re-enter. This varies by product. Check the SDS and product label; many professional rodenticides and insecticides require 2–4 hours before re-entry, some longer. Communicate this clearly to the customer in writing.

Writing the Treatment Plan

The treatment plan is the output of the survey and COSHH assessment. It should be a written document given to the customer before work begins (or at least on the same day). Minimum contents:

• Property address and date of survey
• Pest species confirmed
• Severity score (low/medium/high) and basis for that score
• Products to be used (name, active ingredient, formulation)
• Locations where products will be applied (keyed to a site sketch)
• Restrictions — access to treated areas, time period
• PPE to be used by the operative
• Environmental constraints and how they are managed
• Proofing recommendations (if any)
• Follow-up visit dates and what will be checked
• Operative name and qualification/certification number

For commercial contracts, the treatment plan is usually a formal document with the customer's signature. For domestic one-off jobs, a clear written job sheet serves the same legal purpose.

Infestation Severity Scoring

There is no universally mandated scoring system in UK pest control, but a consistent internal system is important for three reasons: it supports treatment decisions, provides before/after comparison on follow-up visits, and demonstrates professional methodology if a complaint arises.

A practical three-tier system:

Low severity — Pest is present but activity is limited. Fewer than 5 rodent droppings in a given area, a single wasp nest, one cockroach sighting in a kitchen corner. Treatment is targeted and proportionate. A single visit with monitoring may be sufficient.

Medium severity — Active, established infestation. Rat runs with fresh smear marks, regular rodent sightings, multiple cockroach life stages present (indicates breeding). Requires a multi-visit programme, with treatment at each visit and proofing recommendations made.

High severity — Structural harbourage, large populations, health risk. Rats breaching internal walls, cockroach populations in multiple rooms, bed bug infestation across multiple rooms in a HMO. Requires intensive treatment, often daily or twice-weekly visits initially, and may require escalation to the local authority environmental health team.

Follow-Up Schedule Planning

Follow-up is not optional — it is the only way to confirm the treatment has worked and to identify re-infestation early. The schedule depends on pest type and severity:

Document follow-up findings: pest activity score at each visit, bait consumption recorded (for rodenticides, quantity placed and quantity remaining), any live activity confirmed, any new entry points identified.

Reporting Obligations

For certain infestations and certain settings, there are additional reporting obligations:

• Food businesses: if pests are identified in a food preparation area, the food business operator has a duty under the Food Safety Act 1990. The pest controller's report may be used by an Environmental Health Officer (EHO) during an inspection. Issue a clear written report immediately, even if the infestation is minor.
• Registered housing: housing associations and local authorities contracting pest control services typically require monthly service reports and an annual audit document.
• Notifiable pests: the brown rat is not notifiable in England, but local authorities have powers under the Prevention of Damage by Pests Act 1949 to require landowners to control rat infestations. If you find a severe infestation in a property where the owner is unresponsive, this legislation provides the escalation route.
• SGAR reporting: second-generation anticoagulant rodenticide use must comply with CRRU Stewardship reporting requirements. See rodenticide second generation anticoagulants.

Frequently Asked Questions

Is a risk assessment required for every job, even a simple one-off?

Yes. Under COSHH and the Health and Safety at Work Act, the requirement applies whenever a hazardous substance is used at work. A "simple" wasp job still involves a professional insecticide. The depth of the assessment can be proportionate to the risk — a brief written job sheet covering the product, hazards, controls, and PPE is sufficient for low-risk domestic work. What is not acceptable is no record at all.

Who needs a BASIS PROMPT certificate?

Anyone who uses professional-use pesticide products as part of their work must either hold a BASIS PROMPT certificate of competence (or equivalent recognised qualification, such as RSPH/NPTC Level 2) or be under the direct supervision of someone who does. Using professional rodenticides, insecticides, or fumigants without qualification is illegal and invalidates public liability insurance.

How do I score an infestation I've never seen before?

Use the observable indicators: number and freshness of droppings, presence of smear marks or active runs, sightings during the day (diurnal activity often indicates high population pressure), evidence of breeding (young rodents, cockroach egg cases), structural damage. If in doubt, score medium rather than low — it is safer to over-treat and scale back on follow-up than to under-treat and return to a worsening infestation.

Does the customer need to sign the treatment plan?

For commercial contracts, a signed treatment plan is strongly recommended and often contractually required. For domestic one-off jobs, getting a signature is good practice but not legally mandated. What is mandatory is that the customer receives clear written information about the products used, access restrictions, and follow-up requirements — the Health and Safety (Information for Employees) Regulations 1989 and product label requirements underpin this.

What happens if a follow-up visit finds no improvement?

Re-assess the survey findings. Common causes of treatment failure: product resistance (common in rats and some cockroach strains), untreated harbourage, new infestation source identified, product degraded due to environmental conditions (e.g. moisture deactivating dust). Document the findings, revise the treatment plan, and if required, change product or method. If resistance is suspected (particularly for rats with SGARs), switch active ingredient class and report to the Rodenticide Resistance Action Group (RRAG).

Regulations & Standards

• Control of Substances Hazardous to Health (COSHH) Regulations 2002 — mandatory risk assessment before using any pesticide

• Health and Safety at Work etc. Act 1974 — general duty of care; underpins all risk assessment requirements

• Management of Health and Safety at Work Regulations 1999 — requires "suitable and sufficient" risk assessment

• Control of Pesticides Regulations 1986 (as amended) — pesticides must be used safely, effectively, and humanely

• Food Safety Act 1990 and Food Hygiene (England) Regulations 2006 — food business operators' duty to control pests

• Prevention of Damage by Pests Act 1949 — local authority powers to require rat control

• HSE EH40 (Workplace Exposure Limits) — reference document for WELs used in COSHH assessments

• HSE — COSHH: A brief guide to the Regulations — accessible summary of COSHH requirements

• British Pest Control Association (BPCA) — Guidance and Code of Practice — industry standards and best practice

• National Pest Technicians Association (NPTA) — training, qualifications, and survey guidance

• HSE — Pesticides: safe use — professional use, certificates of competence, regulations

• BASIS PROMPT — pesticide users' certificate of competence scheme

• wasp and bee nest removal — species identification and legal requirements before treatment

• rodenticide second generation anticoagulants — SGAR stewardship and use conditions

• pest control in domestic properties — tenant/landlord responsibilities and domestic treatment constraints

• fumigation regulations — confined space and certification requirements for fumigation work