Controlling Legionella in a Large London Hotel

Controlling Legionella with Geosil50, the ONLY GB BPR authorised silver stabilised hydrogen peroxide biocide

Controlling legionella become a major issue for the facilities manager of a large hotel group in central London. The hotel contacted us following confirmed positive legionella samples isolated from a number of outlets.

This post shows how Geosil50, the leading silver stabilised hydrogen peroxide, provided the solution to this problem.

The hotel in question has over 400 guest bedrooms & suites, with extensive facilities for meetings, functions and other events.

The building is served by a single incoming water main

This main feeds a water softener and a split cold water storage cistern. The cold water storage cistern is on the lower basement level. One compartment of the cistern is fed with softened water and the second with raw mains supplied water. Water from these compartments feeds the booster pump set which supplies water to the two cold water storage tanks in the hotel’s roof plant room.

These supply the hotel’s cold water down services, the calorifiers and the plate heat exchangers in the basement, which in turn supply the domestic hot water.

The hotel population reflects a similar cross section to that of the general public and so the Legionellosis risk associated with people using the hotel is comparable to that found in the general population.

With the hotel open to residents, conference/seminar delegates and the general public with many hundreds of people entering and leaving the premises every day it was imperative that urgent action be taken to get the bacteria levels under control and the system fit for use.

The HSE Approved Code of Practice (ACOP) L8 for the control of legionella in water systems, is for Duty Holders, i.e. those in control of premises and those with health & safety responsibilities for others, to help them comply with their legal duties in respect to legionella.

HSE Technical Guidance HSG274 again refers specifically to the control of legionella in hot and cold water systems, and is for Duty Holders, i.e. those in control of premises and those with health & safety responsibilities for others, to help them comply with their legal duties.

In the event of a breach of health and safety law, it is vital to show that the law has been complied with by following the advice provided by HSE, as detailed in ACOP L8 & HSG274.If it is shown that a Duty Holder did not follow the advice given, he or she would have to show that they had complied with the law in some other way or a Court would find them at fault.

The Approved Code of Practice (ACOP)L8 in PDF format can be downloaded here HSE ACOP L8HSG274 Parts 2 & 3 in PDF format can be downloaded here HSG274 Part 2 & here HSG274 Part 3

Following the protocol laid out in HSG 274 and the Geosil50 method statement, the property’s cold water storage tanks were dosed with a contact time of three hours.

Minimising disruption to the hotel and in accordance with The British Standards document PD 855468:2015 – Guide to Flushing & Disinfection of Domestic Water Services, guests were informed of the disinfection process and appropriate labelling put in place.

Geosil50 was flushed through to the infected outlet and the identified sentinel points in the building.  Re-sampling of the system was performed 48 hours later and the results returned non-detectable levels of legionella.

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