Temporary Closure of Swimming Pools- Guidance

HSA: Control of Legionella Bacteria During and After the COVID-19 Pandemic 

Below are some of the guidelines for shutting down and limiting the effects of closure and reduction in Staffing and trying to reduce running costs:

  • Never shut the pool plant down and leave the water to stagnate
  • Always keep the Pool water circulating and the automatic dosing unit operational.
  • If you will have limited staff access to check dosing tanks etc, you may increase the Free Chlorine to between 5 and 8 Mg/L, via manually dosing the swimming pool before closure.  Leave the Auto Doser on as normal and as the free chlorine becomes used, this will keep the levels up to normal amounts as long as the Day Tanks have been refilled.  As a minimum, the Pool should then be checked on a weekly basis but more often as staffing allows.  You can repeat the manual dosing as your pool demands.  Ideally you would be checking the Auto Doser regularly and not having to manually dose.
  • Keep the pH as close to 7.2 as per normal guidelines and this will ensure that the free chlorine is at its most effective.
  • As all Pools are different, when there is no new contamination being introduced, this should be sufficient for most Pools.
  • Ideally Backwash the filters for as long as is possible before closure to ensure as much contamination has been removed from the filters.
  • Continue to add Flocculent/Coagulant as normal, if you already do so.
  • You should not need to backwash as there will be very little contamination in a closed Pool, however, if the period is extended into months, then you may consider doing a backwash once a month to keep fresh water being introduced to the Pool.

In Order to reduce running Costs:

  • The heating of the swimming pool water is one of the most expensive costs in the Facility.  When bathers are not using the pool, we can now reduce the Temperature of the Pool to a background temp of 16-18 C.  We can then also reduce the Pool Hall Temperature accordingly, to remain 1-2 C above the water temperature.  You will obviously be covering the swimming pool with the pool cover until reopening.  You will need to check for condensation and monitor on a weekly basis.
  • Most of the Building Management Systems will reduce the Pool Hall temperature to a background temperature during the night time when the pool covers are on to reduce running costs when closed.  We are mimicking this for the extended closure.
  • By reducing the Temperature Set Point the pool will start to cool gradually while the Pool Covers are still in place.  There will not be a drastic decrease in temperature and should not harm the pool structure.
  • Remember that it will take a considerable time to reheat the pool water before re-opening.  This may take 5-7 days of full heat, depending on the volume of the pool and how efficient the heat exchangers are.  As we approach a date of re-opening we can increase the set point to ensure that the pool is sufficiently warm before re-opening.
  • You will need to continue to run all air handling units in the pool hall to ensure no condensation and stale smells, legionella, etc build up on any surfaces.
  • In Changing Rooms and other area, you can afford to cut back on hours of use, but it is recommended that some hours are still circulating.  This will vary from facility to facility, but monitor and if you find damp smells, condensation or other signs, then increase the number of hours running time.  These areas can reduce the temperature set point accordingly.

Spa Pools and Smaller Toddler Pools (on their own circulation system)

  • The Spa pools should be emptied and cleaned as much as possible and leave to be refilled a week before estimated opening.  Due to the high temperatures, etc, these will be expensive to run and also can pose the risk of legionella and bio films.
  • Before closing, boost the free chlorine up to 10Mg/L and allow the bubbles and air pumps to run a number of cycles.
  • Backwash and empty the Spa Pool
  • Clean all accessible areas
  • Clean the balance tank
  • Switch off
  • Leave ready to be refilled approx 1 week before reopening and then refill and run to ensure full chlorination.
  • Smaller toddler pools with their own circulation systems may be emptied and cleaned down in a similar manner to above – this may be the most economical option for a smaller pool.

The above information is to be used as guidelines and where possible, the installers and maintenance companies of the both the Pool Plant and the Air Handling Units should be consulted before making changes to time schedules, temperature set points and before switching off completely.  All plant is the responsibility of the operator and you should make any checks necessary and should monitor all changes and outcomes.

Temporary Closure of Pools/PWTAG Guidance

The Pool Water Treatment Advisory Group (PWTAG) have issued guidance for temporary pool closures and we will update our own guidance based on this. Please monitor their website here.

ESGLI Guidance for managing Legionella in building water systems during the COVID-19 pandemic

Legionella and reducing the risk of Contamination while closed, these are the guidelines:
1. Nominate one person to be in control of Legionella while closed
2. Create a checklist of what needs to be done and tick off as completed.
3. Keep hot water circulating at between 50 and 60 C while closed
4. Cold water should be as cold as possible
5. Run all taps, showers, toilets and any water outlets for 5 minutes at least once a week.
6. Wash and disinfect Shower Heads before re-opening
7. If the heating system is switched off completely, disinfect with 50mg/L chlorine for 2-4 hours before restarting. (If continuously running, this should be done once a year)
8. Disinfect any water filters (water drinking fonts etc) before re-opening and use manufacturers guidelines.
9. Empty Spa Pools and clean and disinfect the balance tank while not running. When refilling, raise the Free Cl to above 10mg/L and allow to run for 24hrs before emptying again and refilling before starting to use again.
10. If in any doubt, always test the water for legionella before re-opening.
11. Constantly check for any stagnant water building up in any area and remove asap- this would include in and around air handling units also. legionella will develop in any stagnant water – storage tanks, cooling towers, puddles, etc.
12. Visit the HSE website regarding Legionella.
The secret to controlling the potential of Legionella is to keep circulation and the introduction of fresh water continuously and stop stagnation. Prevention is much better than cure, so regular flushing and running of taps/showers is the more economical way to control Legionella.