Use of Water System Disinfection and Other Methods to Counter Legionella

Legionella bacteria are typically found in water. Such bacteria when in high concentration can cause Legionnaire’s disease. This is a form of pneumonia that is potentially fatal and contracted commonly by inhaling water droplets containing Legionella bacteria.

Almost anyone can contract this disease, but the more susceptible group include smokers, those with weak immune systems and the elderly.

Factors That Encourage Growth of Legionella

A variety of external and internal factors can lead to a Legionella issue in your building like:

  • Main breaks of water
  • Construction
  • Biofilm
  • Changes in the quality of municipal water
  • Sediment and scale
  • Fluctuations in water temperature
  • Fluctuations in pH
  • Insufficient levels of disinfectant
  • Stagnation of water
  • Change in water pressure

Steps to Contain Contamination

A variety of measures are helpful in preventing the growth of Legionella and water system disinfection:

  • Control temperature of the water

Legionella bacteria grow most within the temperatures between 77-degree F and 108-degree F. Keep water apart from such temperature levels, keeping cold the hot water and hot, the cold water in the system.

  • Right amount of disinfectants

When there is a waning of disinfectant levels in water systems of buildings, it can lead to the growth of Legionella. The water supply of the building may require long term disinfectants supplemented to the water to limit the growth of Legionella. Many companies offer water system disinfection services for preventing the growth of biofilm.

  • Prevent stagnation

When there is a barrier to the flow of water, it stagnates and builds up the content of biofilm. It is vital to understand the flow of water fully in the building to identify areas of potential risk where there may be stagnation of water and encouragement to the growth of Legionella bacteria.

  • Operating and maintaining equipment

Operating and maintaining the equipment of your building will be effective to prevent biofilm from contaminating your water system that offers conditions and habitat for the growth of Legionella.

  • Monitoring external impacting factors

While monitoring the growth of Legionella, some vital factors include main breaks of water, construction, and changes in quality of water supply by the municipality. Such changes must be monitored, and it must be ascertained how such changes can impact the complete water system of the building.

Some of the devices within the facility or building can cause the spread of water droplets that are contaminated. The devices that must be monitored include water heaters, cold and hot water storage tanks, expansion tanks, water hammer arrestors, water filters, aerators, manual and electric faucets, restrictors of faucet water flow, hoses & shower heads, fittings, valves & pipes, centrally installed humidifiers, air washers & misters, humidifiers with the non-stream aerosol generation, less frequently used equipment such as eyewash stations, hot tubs, ice machines, decorative fountains, medical devices and cooling towers.

Modes of Preventing Outbreaks

Systems and Tanks

  • Systems should be designed with no dead legs and must have short pipes.
  • Tanks should be connected in series to get rid of stagnant water.
  • Experts recommend the use of non-metallic tanks like rubber or fibreglass.
  • Coldwater must circulate below 20 degree C, and hot water must be stored above 60-degree C.
  • An annual inspection of Calorifiers and storage tanks to remove all sludge, scale and sediment and sterilizing prior to returning to use.
  • Routine disinfecting and de-scaling of showerheads.

Cooling towers

  • Colling towers must be positioned maximum away from ventilation inlets and air-conditioning and from windows that stay open.
  • Cooling systems must have a routine water treatment program to monitor, measure and control corrosion and scale.
  • There must be alternate use of complementary biocides for week-based shock treatment. For limiting the concentration of salts, there must be constant blowdown.
  • Every six months, one should conduct checks for Legionella.
  • Disinfection via water system disinfection is typically by chlorination such that a level of a minimum of 20 ppm of free residual chlorine can be maintained for a given period in cooling towers and higher levels for storage tanks.

Water treatment

  • Water treatment services must be conducted by only suitably trained personnel, making use of suitable safety equipment. This comprises of donning protective clothing and arranging for the use of first aid facilities. One must take care not to damage equipment which may be impacted by the process of chlorination.
  • Effluents emerging from maintenance and cleaning should be neutralized by a hose and directed to a foul sewer. This is only after gaining permission to discharge to the sewer from the suitable authorities.

These are all tips for preventing and dealing with Legionella bacteria.

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