First 30 minutes — operational priority
The forensic response sits behind the operational and medical response. In the first 30 minutes:
- Patient care and emergency services as the immediate priority
- Make the area safe — barriers, signage, redirect users
- Lifeguards and witnesses on scene; pool not yet closed if not necessary
- Internal incident report initiated
Once the operational situation is stable, the forensic capture begins.
First 2 hours — evidence preservation
- Photograph the immediate area extensively — wide shots, close-ups, multiple angles
- Capture the surround as found, before any cleaning or alteration
- Photograph any visible contamination (sun cream, body oil, pool chemicals, hair, soap residue)
- Photograph the lighting, the signage, the drain locations
- Photograph anyone present at the scene if witnesses (with consent)
- Note the date, time, weather (for outdoor pools), recent plant chemistry state
- If possible, photograph the patient's clothing and footwear (with consent) — particularly the sole/skin contact surface
First 24 hours — witness statements
Witness recollection degrades fast. Within 24 hours:
- Take written statements from staff witnesses (lifeguards, reception, cleaning staff)
- Capture contact details for guest/member witnesses
- Record what each witness saw, where they were, what the patient was doing immediately before the slip
- Record the activity of cleaning, plant operation, signage and supervision in the moments before the incident
Statements taken in the first 24 hours are evidentially much stronger than statements taken weeks later.
Days 2–7 — UKAS pendulum testing
This is the window for forensic pendulum and Rz testing while the surround is most likely to still reflect incident-time conditions. Instructing testing within this window is the difference between strong evidence and weakened reconstructive evidence.
For matters likely to lead to claim or litigation, instructing UKAS-accredited testing within 7 days of the incident is the gold standard. Within 2 weeks is still strong; beyond a month is qualified.
Pool plant chemistry log
For the days surrounding the incident, the pool plant chemistry log should be retained:
- Free chlorine residual readings
- pH readings
- Calcium hardness (less time-critical but worth capturing)
- Salt level (if salt-cell pool)
- Any shock dosing in the preceding week
- Any pH excursions or correction events
- Plant maintenance activities (filter backwash, chemical refill, equipment service)
This data feeds into both the technical investigation and the formal incident record.
Chain of custody for retained samples
If any portion of the surround is removed (for inspection, treatment, replacement), retain offcuts as evidence with documented chain of custody:
- Date and location of removal
- Photograph of the removed section in situ before removal
- Identification of the contractor who carried out the removal
- Storage location of the retained sample
- Subsequent handling (laboratory testing, expert inspection, transfer to legal team)
Retained samples can be Rz-tested even where the in-situ surround has subsequently been replaced. Without chain of custody documentation, the sample's evidential value is much reduced.
What not to do
- Do not deep-clean the area immediately after the incident — the contamination state at incident time is evidence
- Do not apply anti-slip treatment to the area before testing — this destroys baseline evidence
- Do not replace surround tile in the area before retained samples are secured
- Do not let the pool plant log fall behind during the investigation period
- Do not delete or overwrite CCTV from the period covering the incident