Chemical Assistance – Cleaning and Disinfection

Using a disinfectant

Cleaning and Disinfection

When carrying out cleaning and disinfection tasks it is important that you use the correct materials and chemicals for each task so that cleaning is effective and to minimise the chances of cross-contamination occurring.


Chemicals (for example washing-up liquid) used to remove grease, dirt and food. Detergents help clean away grease or oils and dirt but do not kill bacteria.


Chemicals that kill bacteria but do not clean. Once surfaces or equipment are cleaned of grease and dirt you can use a disinfectant to kill bacteria. If you use a disinfectant you should use a food-safe variety. Some will need to be rinsed off thoroughly after use.


Sanitisers act as both a detergent and a disinfectant. You should choose a food-safe sanitiser that can be used directly on food surfaces and equipment.

Contact time and dilution rates

With any chemical it is important that you always follow manufacturer’s instructions – especially where dilution is required when making up solutions.

Some cleaning chemicals are concentrated, so you need to add water to dilute them before they can be used. You should follow the manufacturer’s instructions on how much water to use with the chemical. This is known as the ‘dilution rate’. If you add too much or too little water, then the cleaning chemical might not work effectively or may be so concentrated that it presents a chemical hazard. Chemical suppliers may provide dosing aids and applicators to assist with dilutions. To eliminate the risk of errors it is recommended that you use chemicals that have already been prepared by the manufacturer and are ready to use undiluted.

The instructions may also give details of a contact time. The contact time tells you how long a cleaning chemical needs to be left on the item you are cleaning. If you do not allow enough contact time before rinsing or wiping the solution may not be effective at killing bacteria. Chose a brand with a lower contact time for practicality.

There are other precautions that can be applied to cleaning equipment and materials, for example:

  • You should never transfer chemicals from their designated spray bottles or containers;
  • Each chemical container should be labelled clearly to prevent them from being used incorrectly;
  • All chemicals should be stored well away from food to avoid the potential for contamination; and
  • It is also necessary to store cleaning equipment such as mops and buckets away from food. You will need to designate a separate area for this purpose.

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