- Requirement of contract - often prior to hand over a new building or following modification of existing pipe work the client will ask
for disinfection of the relevant services and supply of a chlorination certificate.
- Following a period of non use - the HSE recommend that all hot and cold water services should be flushed weekly. Where this is not followed or
possible the water may stagnate and deteriorate which in some cases can lead to colonisation of pathogens such as legionella.
- After contamination of a water system - this maybe after widespread detection of legionella bacteria or post
contamination event (such as dead animal in water tank).