Water Hygiene and Legionella RAMS Guide for UK Contractors

Key Topics in a Water Hygiene RAMS

Flushing and disinfection

New or altered water systems must be flushed to remove debris and biofilm before being put into use. Where Legionella risk has been identified, chlorination disinfection to 50 mg/l free chlorine for 1 hour (or as specified in BS 8558 / L8) is required before flushing out and commissioning. The RAMS must describe the flushing and disinfection procedure, the competence of the person carrying it out, and how results are recorded.

Temperature monitoring

Hot water must be stored at 60°C or above and distributed at 55°C or above. Cold water must be stored and distributed below 20°C. The RAMS must describe how temperatures are verified during commissioning and the monitoring regime going forward. Temperature records must be retained.

Dead legs

Dead legs — sections of pipework with no or low flow — are primary Legionella risk points. The RAMS must identify dead legs created or retained during the works and describe how they are managed: removal is preferred; where retained, a flushing schedule must be established and documented.

Water sampling

Pre-occupation microbiological sampling may be required, particularly after extensive pipework work or system shutdown. The RAMS must state whether sampling is required, who carries it out, the laboratory used, and the action threshold for positive results.

Competence and records

Water hygiene work must be carried out by, or under the supervision of, a competent person — one with sufficient knowledge of L8 ACOP, BS 8558, and the specific system type. The RAMS must name the competent person, state their qualification (e.g. City & Guilds Water Hygiene, IOSH, or equivalent), and confirm that records will be retained in the logbook.