As we are Returning to Normal Service
With many community facilities/businesses being closed during the COVID-19 4-week self-isolation period this provides the opportunity for drinking-water quality issues to occur upon return to normal service activities. These issues are most likely to arise when water is used for the first time given the water may have been sitting idle in your pipes and stagnated or deteriorated.
The water quality issues that result from water sitting stagnant are:
  • Poor tasting (may taste metallic or earthy)
  • Odorous (smells bad)
  • Looks brown or dirty
  • May have grown biofilm (small naturally grown vegetative matter).
These issues alone don’t mean the water is unsafe, it just may not be pleasant.
There are two overall groups the above issues particularly apply to:
Community facilities/commercial buildings/small businesses;
Group A – are provided with a municipal water supply (i.e. via your local Council)

Group B – have your own standalone water supply (roof water or private bore/spring)

The types of community facilities/businesses that fall into either category include:
  • Educational facilities – Schools, Colleges, Early Childhood Centres, Te Kōhanga Reo, Universities/Polytechnics
  • Commercial premises (single to multi-story sized premises)
  • Marae and Papakāinga
  • Community facilities – halls, kindergartens, religious centres, churches
The following actions are recommended to be undertaken PRIOR to returning to normal activities/services.
The following actions are recommended to prevent water quality issues arising:
Group A
If you fall into this group the Ministry of Health recommends you undertake the following actions:
  • Sufficiently flush all of your taps/faucets so that the water is clear or appears normal
    • Please note flushing may take longer if you have a large premises or there are still water quality issues after flushing has been completed.
  • When flushing your taps it is recommended you use an outdoor tap which is at the furthest point from the road and any faucets (or fountains) that you drink from.
IMPORTANT: Prior to undertaking any flushing please contact your local Council as they may need to advise of an appropriate day and time to flush your system so that this does not create demand issues for the whole supply.
Group B
If you fall in to this group the Ministry of Health recommends you undertake the following actions:
  • Check your water tanks for the following;
    • Check your water tank has enough water to ensure you have adequate capacity/volume to operate upon return to normal service activities
    • Check for any observable physical matter in the tank (i.e. Animals / leaves etc)
  • Check that all localised treatment systems are operating correctly such as;
    • Pumps are working correctly
    • Filters are checked and that they are in good condition and operating correctly or have been replaced
    • UV systems are turned on and working correctly
    • There’s sufficient chemical stocks for treating water (i.e. chlorine solutions)
  • Check for any blockages, leaks or breaks in pipes and taps and fix these where required
  • Sufficiently flush water so that is clear or appears normal
    • When flushing water it is recommended you use a tap which is at the furthest point from your source/treatment.
NOTE: it is recommended you run your treatment systems prior to returning to normal so that you know the system is working correctly in advance.
If you are still having issues with maintaining your drinking-water quality after applying the above activities it is recommended that you contact your local Council OR water services provider for further advice and support.
Questions and Answers (Q&A)
 Who should I contact to find out about where my water supply comes from?
Please contact your local Council as they will be able to advise you of this.
Prior to lockdown the Council had water restrictions in place, do I still need to adhere to these?
If you fall into Group AYes. Please contact your local Council directly as they will advise you of what rules/requirements may need to be applied PRIOR to implementing the actions listed in this guidance material.
If you fall into Group B – No. Although, you may want to ensure you have enough water (capacity/volume) to operate upon return to normal business.
If I have been regularly using my taps during the 4-week self-isolation period – do I need to flush them?
No. If you have been regularly using your water supply it is less likely that issues would have arisen.
Why is my water still cloudy?
Run your outside tap for a further 10 minutes and try it again. If the problem persists, please contact your local Council or water services provider. 
My water tastes funny?
If it hasn’t already, your water should return to its normal taste soon especially if you have applied the recommended activities.
Do I need to get my water tested?
If you fall into Group B it is recommended that you continue your normal sampling and monitoring practices.
I’m on a water tank – is it safe to use?
If your tank is filled by truck, the water should be safe to drink as this water should already be disinfected.
If your tank is filled by rainwater, carry out the activities suggested. Alternatively, if you want to take further measures to safeguard your water supply tank you can use common household bleach from the supermarket. Bleach must be unperfumed (i.e. plain). Check the size of your tank in cubic meters (one cubic meter is 1,000 litres). Add 167ml of bleach per cubic meter, e.g. if you have a 22 cubic meter tank you must add 22 x 167 = 3.7 litres of bleach. Mix and leave for one hour before drinking (ideally leave overnight). If your tank is not full then you must adjust the amount of bleach to add, i.e. if you have a 22 cubic meter tank but it is only half full, then add 0.5 x 3.7 = 1.8 litres of bleach.
Do I need to change my water filters / UV lamps?
Continue your normal maintenance regime, as per manufacturer’s instructions.
I am a registered food premises, what should I do to check that my water is suitable to prepare food?
If you are a food premises/manufacturer (such as a dairy or bakery), it is recommended that you contact MPI for specific guidance about returning to normal service AND whether further actions such as clearance sampling are required beyond this guidance material.
For more information, visit, email or phone 0800 00 83 33.
My building/facility has a cooling unit (tower) and hot/warm water system in my building – is there a risk from harmful legionella bugs and what should I do to check that my system is ok?
 Legionella bacteria can infect humans and cause legionellosis and Legionnaires’ disease. Legionella can be spread through aerosolised droplets from building systems such as cooling towers, evaporators, or domestic hot, warm and cold systems (i.e. hot water cylinders and sanitary fittings (showers)). Risks arise when these systems either; (a) do not maintain high enough temperatures (>60°c) to prevent Legionella growing, OR (b) in the case of commercial (industrial) cooling towers/evaporators are not routinely maintained and disinfected.
Prior to returning to normal service activities it is highly recommended that you thoroughly inspect your buildings systems to ensure they are clean, well maintained, and working correctly.
For further information please refer to the following guidance:
Download Preventing Legionnaires’ disease from cooling towers and evaporative condensers
  1. Environmental Sampling for Legionella Bacteria – available from the Institute of Environmental Science and Research.
  2. The Prevention of Legionellosis in New Zealand: Guidelines for the Control of Legionella Bacteria – available from the Ministry of Health.
  3. The following standards are available from Standards New Zealand
    1. AS/NZS3666.3 Air handling and water systems of buildings – Microbial control – Part 3: Performance based maintenance of cooling water systems
    2. NZS4302 Code of practice for the control of hygiene in air and water systems in buildings
    3. AS/NZS4020 Testing of products for use in contact with drinking water.

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