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​​When notified by ºÚÁϳԹÏÍø Health that two or more cases of cryptosporidiosis have been associated with a public swimming pool, spa pool or pool complex, carry out hyper-chlorination:​​​

1. Close affected pools including pools using common water while hyper-chlorination is carried out.
2. Adjust pH to 7.5 or lower
3. Hyper-chlorinate the affected pool by dosing the water to achieve a free chlorine CT value of 15,300 mg.min/L for inactivation of Cryptosporidium, where CT value=chlorine concentration x contact time in minutes.
   
   For example, free chlorine concentration of 20 mg/L for 13 hours or 10 mg/L for 26 hours or via alternative combination of chlorine concentration and time that achieve the required CT value of 15,300 mg.min/L.
   
   Pools using chlorine with cyanuric acid, ensure the cyanuric acid is 15 mg/L or less.  Use unstablised chlorine to achieve a free chlorine CT value of 31,500 mg.min/L for inactivation of Cryptosporidium.
   
   For example, free chlorine concentration of 20 mg/L for 28 hours via alternative combination of chlorine concentration and time that achieve the required CT value of 31,500 mg.min/L. 
   
4. Check filtration (and coagulation if applicable) is efficient.
5. Once the required free chlorine CT value has been achieved, backwash the filter to waste or replace media / cartridge as appropriate.
6. Test the free and total chlorine concentration in the pool and when less than 10 mg/L re-open pool(s).
7. Log the incident and remedial action taken.

For more information on Cryptosporidium risk management contact your local Public Health Unit on 1300 066 055 for advice.