Control of legionella (and other) bacteria in metal working fluids (MWFs)

Legionella bacteria are commonly found in water supplies at low concentrations and if conditions (eg temperature and nutrients) are right, these microorganisms will grow. Water mix metal working fluids (MWFs) are mostly water and their industrial use may produce aerosols. Inhaling an aerosol contaminated with Legionella bacteria can cause Legionnaires’ disease. HSE guidance L8 “Legionnaires’ disease. The control of legionella bacteria in water systems” recommends that the MWF storage and distribution system of lathe and machine tool coolant systems should be cleaned and disinfected every six months or more frequently if recommended by machine tool or fluid suppliers.

However, the Health and Safety Laboratory has carried out research, Survival of Legionella pneumophila in metalworking fluids, which shows there is a minimal risk of Legionella bacteria contaminating such a system, if the system is properly managed.

HSE’s guidance on managing bacterial contamination of metalworking fluids suggests a risk-based approach, based on monitoring fluid condition and bacterial contamination:

If you can demonstrate that metalworking fluids are managed in accordance with the COSHH essentials sheet Managing sumps and bacterial contamination ( and HSE’s guidance on managing bacterial contamination in metalworking fluids an additional assessment of the risk of Legionnaires’ disease is normally unnecessary. However, further assessment and precautions will be necessary to cover any special circumstances, such as deep cleaning of sumps and machinery with jet washers, where the potential for exposure to airborne hazardous bacteria is much greater. This is due to the disturbance of microbial slime known as biofilm – where Legionella may survive. Avoid water jetting where possible, as it tends to create fine water droplets or mists.

If water jetting is necessary carry out a risk assessment, to include respiratory and other risks such as those arising from the use of high pressure and electricity, see,

More guidance on metalworking fluids can be found on the HSE web page:

For more information on controlling the risk of Legionnaires’ disease, see Legionella and Legionnaires’ disease:, or contact us on 07896 016380 or at, ad we’ll be happy to help

Contains public sector information licensed under the Open Government Licence v3.0.


Pressure systems – company fined for safety failings resulting in workers death

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Company fined for safety failings resulting in workers death

A Midlands based construction equipment hire company has been fined £800,000 after a worker’s death.

Warwick Crown Court heard how the 49-year-old had only been working for the company for 16 days when the fatal incident happened. The court heard how he was testing a hydraulic cylinder when it cracked under pressure causing a piece of metal to strike him violently in the head.

An investigation by the Health and Safety Executive (HSE) found the company had failed to have adequate supervision in place for this task and they failed to inform the worker of the safe working pressure for the cylinder he was testing.

The investigation also found that the company also failed to have protective screens in place to prevent projectiles injuring staff. They also did not exclude other people from the test area.

The company pleaded guilty of breaching regulation 12 (1) of the Provision & Use of Work Equipment Regulations 1998 and regulation 3 (1) of the Management of Health and Safety at Work Regulations 1999.

The company also pleaded guilty to breaching section 3(1) of the Health and Safety at Work Act 1974.

Speaking after the case HSE inspector Neil Ward said: “This was a tragic incident that should never have occurred.

“It is a company’s obligation to provide a safe system of work for leak testing. This will include protecting people from flying fragments and high pressure oil leaks as well as providing thorough training in how to carry out the work safely.”

Pressure systems

Pressure systems can range from steam-generating commercial coffee machines to large boilers. When using pressure systems every employer or self-employed person has a duty to provide a safe workplace and safe work equipment. Designers, manufacturers, suppliers, installers, users and owners have additional health and safety duties.

About pressure systems

The main regulations covering pressure equipment and pressure systems are the Pressure Equipment Regulations 1999 (PER) and the Pressure Systems Safety Regulations 2000 (PSSR).

Examples of pressure systems and equipment are:

  • boilers and steam heating systems
  • pressurised process plant and piping
  • compressed air systems (fixed and portable)
  • pressure cookers, autoclaves and retorts
  • heat exchangers and refrigeration plant
  • valves, steam traps and filters
  • pipework and hoses
  • pressure gauges and level indicators

Principal causes of pressure-related incidents are:

  • poor equipment and/or system design
  • poor installation
  • poor maintenance of equipment
  • inadequate repairs or modifications
  • an unsafe system of work
  • operator error, poor training/supervision

The main hazards from pressure are:

  • impact from the blast of an explosion or release of compressed liquid or gas
  • impact from parts of equipment that fail or any flying debris
  • contact with the released liquid or gas, such as steam
  • fire resulting from the escape of flammable liquids or gases

Are you a user of pressure systems?

A pressure system is one that contains or is likely to contain a relevant fluid over 0.5 bar.

The main legislation covering the duties of a user of pressure equipment is the Pressure Systems Safety Regulations 2000 (PSSR).

HSE has produced a number of freely downloadable publications that provide general advice on the duties of the user of pressure equipment. See leaflet INDG261 Pressure systems: A brief guide to safety ( for more detail but, in general terms, the user must:

  • Provide safe and suitable equipment

eg are the right materials being used in the manufacturing process and are modifications/repairs being carried out properly?

  • Know the operating conditions

including the characteristics of the relevant fluid in the system and the safe operating limits of the equipment.

  • Fit suitable protective devices and ensure they function properly

eg devices such as safety valves, bursting discs and electronic appliances, and ensure they are adjusted to their correct settings and in good working order at all times.

  • Carry out suitable maintenance

including a whole-system maintenance programme that considers factors such as age, uses and the environment in which it is operated.

  • Make provision for appropriate training

so that anybody who operates, installs, maintains, repairs, inspects or tests pressure equipment has the necessary skills and knowledge to carry out their job safely. Refresher training should be included.

  • Have the equipment examined

as required under PSSR, including production of a written scheme of examination (WSE), to be used by a competent person to carry out the examination – details in the PSSR Approved Code of Practice (L122).

  • Choose a competent person

ensuring they have the necessary knowledge, skills and, importantly, independence to undertake their role and responsibilities effectively.

For more information, visit the HSE web page: or contact us on 07896 016380 or at, and we’ll be happy to help.

Contains public sector information published by the Health and Safety Executive and licensed under the Open Government Licence