and ensuring return temperatures in recirculating systems do not fall below
Guidance includes avoiding "dead legs" where water can stagnate and ensuring pipework layouts prevent contamination.
BS 8558 sets mandatory protocols for when a system must be flushed or disinfected: BS 8558:2015 - TC | 30 Sep 2015 - BSI Knowledge
Understanding BS 8558: Guidance for Hot Water Systems and Hygiene