Why stagnation matters
When water stops moving, hot water cools, cold water warms and biofilm develops. Within weeks, conditions can suit legionella growth.
A recommissioning checklist
- Check hot water plant is at 60°C and circulating
- Flush all outlets systematically, starting nearest the source
- Check temperatures at sentinel outlets
- Inspect cold water tanks
- Clean and descale shower heads
- Consider disinfection and sampling if the system was not maintained during closure
- Record everything you did
Keeping it safe during closure
The best approach is to keep the system running during quiet periods, with weekly flushing of outlets and normal temperature control.
Frequently asked questions
How long can water stand before it is a risk?
HSG274 treats outlets used less than once a week as little used. Anything that stands longer should be flushed before use.
Disclaimer: This guide is general information about UK requirements and is not legal advice. Always check the current legislation and guidance for your premises.