Control of Legionella in Domestic Hot and Cold Water Systems P900

The P900 – Control of Legionella in Domestic Hot and Cold Water Systems gives you the basic understanding of the subject so that you can either progress in a specific career or take a BOHS proficiency qualification.

Who is it for?

P900 - Control of Legionella in Domestic Hot and Cold Water Systems gives you a foundation level of knowledge on the health risks of legionella, and how to test and monitor for it in domestic hot and cold water systems. It gives you the pre-requisite knowledge required to progress onto Level 4 Proficiency qualifications for legionella, to become water system technicians and operators. 

This course is suitable for anyone who:  

  • Is training to become a water systems operative or technician 
  • Requires a foundation level of understanding to take a Level 4 Proficiency qualification (e.g. P901) 


The level of a course or qualification indicates the relative complexity and depth of knowledge and skills required to complete the course or qualification. This is a level 3 qualification in the BOHS qualifications framework.

How is it delivered?

The P900 course runs typically over one day and includes at least six hours of teaching. 

The course can be delivered more flexibly, such as an evening or part-day course, but should still include six hours of teaching. 

Modules / Learning objectives

Overall objective 

To provide you with a foundation level of knowledge on identifying and controlling legionella risk, to undertake the testing and monitoring of hot and cold water systems in domestic buildings.  


  1. Legionella and health risks  
  2. Legislation and guidance  
  3. Types of domestic hot and cold water systems  
  4. Precautionary measures for legionella control  
  5. Sampling, testing and monitoring regimes  
  6. Maintenance, disinfection and cleaning  
  7. Record keeping 


You must pass a 30-minute multiple-choice examination within 12 months. 


BOHS provides: 

  • Further information can be found in the course specification, under the ‘Downloadable Resources' information box above.
  • BOHS Online Exam information and FAQs - Click here 

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