Legionella testing is asked for in London more often than it is needed, usually because a managing agent or an insurer has used the word. The duty is to assess and control the risk of legionella in a water system. Sampling is one check on whether control is working, not the duty itself, and buying a test while the control scheme is missing answers nothing.
The duty is assessment and control
The responsible person has to assess the risk from legionella in the water system and put in place measures to control it, written down as a scheme with who does what and how often. Temperature control, flushing of infrequently used outlets, and keeping the system free of deposits and stagnation carry most of that in an ordinary building. The record of it done is the evidence.
When sampling is actually indicated
Where temperature control cannot be relied on, where the system uses a control method that needs monitoring, after work on the system, in higher risk systems such as cooling towers and spa pools, and where an outbreak or a case is being investigated. Sampling by a laboratory accredited for it gives a result about the moment the sample was taken and nothing more.
What the London stock adds
Tall buildings with long pipe runs, tanks and pumped risers, a large stock of converted period buildings with pipework of unknown age and route, and many buildings in multiple occupation where nobody has obviously taken the responsible person role. Dead legs left behind by conversion are the recurring finding, because they hold water nobody moves.
Cooling towers and evaporative equipment
Wet cooling towers and evaporative condensers are a higher risk category with their own duties, including notifying the local authority of the device. They cannot rely on temperature control, so treatment and monitoring carry the risk, and here routine sampling is part of the regime rather than a substitute for it.
Legionella testing Manchester and legionella testing UK wide: the duty does not move
The duty is the same in every part of Great Britain, because it comes from the general health and safety duty and the approved code of practice rather than from anything local. What differs between two cities is the building stock and therefore the risk: older converted stock with long dead legs and stored cold water carries more risk than a new build on a mains fed system, and a city with a lot of converted mills or hotels will see more cooling towers and spa pools on the register. So a quote from a contractor in one city and another in a different one should be read as two readings of the same duty against different buildings, not as two local rules.
A legionella survey is a different purchase from a sample
The word survey is used for two things and only one of them is the statutory expectation. The risk assessment is a walk of the whole system, a schematic of what is there, the identification of dead legs, stored water, temperature failures and susceptible people, and a written scheme of control. A sample is a bottle of water and a laboratory result for one point on one day. The assessment is what the regulator asks for; the sampling is what the assessment tells you to do where the control scheme cannot be relied on. Buying the second without the first is buying a number with nothing to compare it to.
Legionella testing frequency, where testing is indicated at all
Sampling has no universal interval because it is not the control. On a hot and cold water system the control is temperature and turnover, monitored monthly to quarterly depending on the point, and sampling is indicated where those cannot be relied on, where the system has been out of use, where there are susceptible people, or to verify after remedial work. On a cooling tower or evaporative condenser it is routine and usually monthly, because the system aerosolises water by design. What the frequency should follow is the written scheme of control, and if yours does not say, that is the gap rather than the sampling.
Questions people ask about legionella testing London
Do I have to test for legionella in a London office?
Not as a routine rule. The duty is to assess and control the risk. Sampling is indicated where control cannot be demonstrated by other means, or where the system is a higher risk type.
Who has to do it in a block of flats?
The person in control of the premises for the common water systems, usually the landlord or managing agent. Inside a let flat, a landlord still has duties for the system they provide.
Does a certificate prove compliance?
No. A laboratory result describes one sample at one moment. What evidences compliance is the risk assessment, the written control scheme and the record of it being carried out.
When is water testing legionella sampling actually needed?
Where the risk assessment calls for it: a cooling tower, a system that has been out of use, a system where control has been lost, or an outbreak investigation. In a controlled system routine sampling tells you less than the temperature records do.
Is water testing for legionella ever routine?
On a cooling tower, yes, on a stated schedule. On an ordinary hot and cold system it is not: the routine work is temperature monitoring and flushing, and sampling is what you reach for when control has been lost or an investigation asks for it.
Does legionella awareness training matter if a contractor does the testing?
Yes, and it is the part most often missing. The duty holder has to understand the system well enough to know whether the control scheme is being followed, because the people who actually cause a failure are on site every day: the flat nobody flushed, the shower head nobody descaled, the tap taken out of use and left connected. Awareness training for the person keeping the logbook, and a named deputy for holidays, is what turns a contractor's visit into a control scheme rather than a folder of results.