Hi

I would like advice on the control measure regarding legionella.

The system is in a single storey shop occupied 6 days a week for 10 hours a day with 6 member of staff which 5 of them work part time. The usage is high with all taps used throughout the day as it is a food shop. The general public has no access to any of the outlets. The systems consists as follow:

The cold water system is served straight from the mains (no storage tanks) and connected to two cold taps, one manual mixer tap and a toilet. There cold water system is also connected to an electric hot water heater with capacity of 50ltrs which has two pressure release valves and 1ltr expansion vessel. The hot hater heater is connected to two hot taps and one manual mixer tap.

After reading HSE guidance I believe the system is a low risk system, however the premises being a commercial building I beleive the following control measures required?

Monthly temperature checks on outlets and flow of hot water heater, annual purging of hot water heater and monthly / 6 monthly flushing and purge to drain of the expansion vessel.

Are these controls appropraite or excessive considering the type of premises.

Yup.  Sounds pretty low risk.  Controls sounds fine assuming you're content there are no deadlegs etc.

Pick a couple of sentinels - a hot and a cold tap and make those your monthly checks.  Document what you've just described as your written scheme and assessment.  Likely no need for a schematic either although it wouldn't hurt to draw out a simple one.  You'll need to periodically review your assessment of risk e.g. if taps fall out of use from some reason.

No need for sampling unless you've got a good reason to (e.g. water is black and slimy. ;) )