Cleanse water mains

Business Sectors (Suites): Water Supply Distribution
Developed by: Energy & Utility Skills
Approved on: 01 Dec 2018


This Standard is about cleansing water mains and pipe work by systematic flushing, water scouring, air scouring or foam swabbing.  This includes making sure the system is configured so that cleansing can be carried out properly, selecting and using the right equipment, cleansing the water mains, disposing of discharged water and making sure water quality meets service level requirements.  This Standard is for anyone who cleanses water mains and pipe work by systematic flushing, water scouring, air scouring or foam swabbing.   

Performance criteria

You must be able to:

  1. ensure an appropriate impact assessment of proposed cleansing activities has been carried out
  2. use information from reliable sources to identify cleansing activities to be carried out
  3. check that cleansing method selected is appropriate for the circumstances
  4. confirm customers have been notified about cleansing activities in accordance with organisational requirements and procedures
  5. confirm system is configured to enable cleansing activities to be carried out
  6. record accurate, relevant information in accordance with organisational requirements
  7. follow safe working and hygiene practices according to relevant procedures, regulatory and statutory requirements
  8. select equipment that is appropriate with the cleansing method to be used
  9. confirm equipment is in the required operational condition and is correctly installed in accordance with the manufacturer's specification and organisational requirements
  10. carry out cleansing procedures in accordance with organisational requirements
  11. dispose of discharged water in a safe manner, and to minimise the effect on the environment, according to organisational requirements
  12. use appropriate tests to confirm the effectiveness of cleansing operations on water quality
  13. resolve problems which occur in line with organisational procedures
  14. inform relevant people of cleansing details in accordance with organisational requirements

Knowledge and Understanding

You need to know and understand:

  1. the reasons for cleansing and the need to cleanse mains
  2. why it may be inappropriate to cleanse mains
  3. organisational procedures for selecting cleansing methods
  4. limitations of cleansing and cleansing methods
  5. preparation procedures and calculations which may need to be carried out including flow velocities
  6. typical and unusual problems which might occur during system preparation
  7. correct and safe use of equipment
  8. the purpose of cleansing and correct and safe cleansing procedures
  9. safe disposal of water
  10. the damage which can be caused by incorrect disposal of water
  11. testing procedures
  12. water quality parameters
  13. typical problems and how to resolve them
  14. who to inform when cleansing has taken place
  15. the cleansing information that needs to be provided
  16. required records of cleansing operations, times and duration of any flow changes
  17. safety and hygiene practices and related regulatory and statutory requirements related to working in the public highway, use of tools and equipment and personal hygiene


Scope Performance

Scope Knowledge





Links To Other NOS

External Links

Version Number


Indicative Review Date

01 Dec 2021





Originating Organisation

Energy & Utility Skills

Original URN


Relevant Occupations

Engineer, Water Inspector, Water Network Controller

SOC Code



Scouring, cleansing, flow velocities, hygiene, water