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Rehabilitating Stagnant Water Systems

28 Apr 2020 9:21 AM | Anonymous


 Rehabilitating Stagnant Water Systems

Post SA Lockdown COVID 19

Dear valued members 

As soon as the South African Lockdown COVID-19 period ends, people will start heading back to their work premises that have for weeks now been unoccupied or sparsely used as a result of the lockdown.

We point out that that water not drawn through a plumbing system within a building over an extended period of time will become stagnant.

Stagnation of water within building pipes and other water systems may contain excessive amounts of heavy metals. As a result this may support the accelerated growth of many microorganisms and pathogens, such as Legionella Pneumophila that can cause great harm to building occupants. Just as with the COVID-19, those that are at the greatest risk of becoming ill from such pathogens are the elderly and those who are immunocompromised.

Plumbing systems will therefore have to be prepared for regular use again and IOPSA urges all its members to please place high importance on protecting the public’s health and safety. Therefore, attention should be given to the rehabilitation of such water systems within 5-7 days before the building is re-occupied. Please note that this period may vary from the periods given by local authorities and this would also need to be taken into consideration.

Below are some guidelines and best practices to be considered to rehabilitate a stagnant water line for regular use again:

Flushing of all water systems

  • ·        All water systems in buildings will need to be thoroughly flushed prior to being put back into service.
  • ·        Flushing includes the opening of all water outlet taps, mixers, showers including toilets and urinals.
  • ·        Flushing the system will purge the stagnant water and improve water quality.
  • ·        Remember to flush all drinking water fountains. Water coolers need to be emptied, cleaned as per the manufacturer’s requirements, and refilled with fresh potable water.
  • ·        All hot water storage heaters (geyser) including point of use geysers would need to be adequate flushed and heated to a minimum of 60 degrees Celsius for at least 1 hour wherever possible.


The flushing of the water system will depend and differ from building to building. Factors such as building reticulation design and distance from service connection will be one of many factors to consider when trying to determine the time per terminal point to be flushed.

Taking the above into account, IOPSA cannot give an exact time to allow such purging of stagnant water from each point.
The licenced plumber will have to evaluate each case on merit and also take into account means to try reduce unnecessary water wastage such as the testing of water quality

IOPSA encourages good health practices and we urge our members and their staff attending to such rehabilitation of stagnant water systems to please take care and wear the correct PPE. Remember to open taps slowly to avoid splashing and before flushing toilets to close the toilet lids to prevent aerosols filling or splashing from the toilet.

Other building water systems

All other water systems in a building, such as water re-use systems (storage tanks), water features such as fountains, and irrigation systems will need to be flushed. Please remember to follow the manufacturer recommendations for disinfecting such water systems. Please refer to SANS 10252-1 ref 6.5.2 and 9.3.2 for more guidance.

Floor drains and grease traps

In respect of buildings that have floor drains - be sure to clean and flush the drain and to make sure that the trap is fully restored in order to keep sewer gases from entering the building.

Grease traps and gulleys need to be cleared, cleaned, and flushed.

Additional considerations

Removal and cleaning of end-point devices such as faucet aerators, drinking fountain, water filtration systems, point of use water heaters and filtration systems would be a good practice.
(Please consult the manufacturer on specific procedures to be followed)

We recommend that should the occupants need to drink water that they either use bottled water or boil the water first and allow it to cool down before consuming it. This should be implemented for at least the first week of re-occupying the building to allow the water lines to be sufficiently flushed.

IOPSA Management and staff take this opportunity to thank each and every IOPSA member for their role and contribution to the plumbing industry and especially to the health and safety of our nation.

Steve van Zyl
National Technical Manager

This document may be amended as we identify new or better remedial procedures and recommendations that can be made in protecting our potable water.

To download the formal statement click here



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