Frequency of pool testing

It is a mandatory requirement (prescribed operating requirement of Schedule 1, Public Health Regulation 2012) for all non-automatic continuously dosed public swimming pools that the disinfectant and pH levels be tested prior to the opening of the pool. The disinfectant and pH levels shall then be tested as frequently as determined by the pool operator depending on the circumstances of pool operation.

It is a mandatory requirement (prescribed operating requirement of Schedule 1, Public Health Regulation 2012) that the disinfectant and pH levels of automatically dosed public pools be recorded prior to opening and once during the opening period. Additionally, the public pool shall be manually tested once a day.

Other mandatory requirements (prescribed operating requirement) are marked by an asterisk (*) in the following tables.

The following recommendations on the frequency of manual pool chemical testing are risk based. This risk is determined according to whether a pool is automatically dosed and the likelihood of a large rapid change in bathing loads. A motel or hotel pool tends to be low risk while learn-to-swim centres for infants are high risk. Spa pools and hydrotherapy pools are all generally high risk.

Evidence has shown that pools which are automatically dosed and frequently tested are more likely to be adjusted according to the bathing load to comply with the criteria. Unfortunately, most manually dosed pools are not frequently tested and studies have shown that these pools are less likely to comply with the criteria (Ford 2004). Testing of pool water to determine its disinfection capacity and to protect public health should be carried out in accordance with the following requirements:

Recommended swimming pool and spa pool testing frequency

Non-automatic continuous dosing /metering high risk pool

High risk pools include spa pools, hydrotherapy pools, baby and infant learn to swim pools, infant wading pools, water features in pools, pools used by incontinent people, or a pool with three or more of the following risk factors:

• pH greater than 7.6 in a chlorinated pool
• consistently poor disinfection (previous chemical or bacteriological criteria failures).
• high turbidity
• poor pool circulation and/or filtration
• high bather loads
• presence of algae
• regular use by birds e.g., ducks
• easy access of foreign material e.g., litter
• biofilms detected
• poor quality make-up water (high in chloramines)

Non-automatic continuous dosing / metering low risk pools

Automatic control dosing

Sampling location

Water samples for chemical testing should be tested immediately after collection. Water should be sampled from a depth of at least 450 mm using an inverted plastic (not glass) beaker in a location away from the inlets (returns). Except for ozone testing, a water sampling point closer to the outlets, gutters or wet deck return, should be selected because it represents the quality of the water leaving the pool. The plastic beaker should be rinsed in the pool water, emptied and then the sample taken by plunging the inverted plastic beaker into the pool, inverting and lifting in the one scooping motion in the direction opposite to the water current.

Water samples for testing ozone should be collected in the same manner as above in a location representing a point closest to an inlet (return).

Sampling to confirm automatic control dosing should be taken from a sample tap strategically located on the return line as close as possible to the control probes and in accordance with any manufacturer's instructions. As the difference between manual pool readings and automatic control measurements will vary, it is the consistency of variation that is paramount. Diverging or converging readings should be investigated.

For microbiological sampling and testing refer to the separate fact sheet.

Testing equipment and testing

Suitable testing equipment must be used to ensure accurate results. All glassware and plastic ware should be thoroughly washed and rinsed after each testing session. The test methodology specified by the manufacturer of the test kit should be strictly followed.

Plastic or Perspex® kits known as '4 in 1' or '5 in 1' kits for backyard pools or test strips are not suitable for testing public swimming pools and spa pools. Photometric test kits are the most reliable test kits, and should be used in preference to colorimetric kits. People with red/green colour blindness must not use colorimetric kits.

Testing should be performed in the shade preferably in a cool, well lit room. Tests of the most volatile chemicals, such as ozone, free chlorine and free bromine should be conducted immediately. If possible, temperature should be measured directly from the pool.

Fresh tablet reagents in unbroken foil should be purchased frequently and stored under optimal conditions specified by the manufacturer. Similarly, fresh liquid reagents should be stored as a minimum in dark, cool conditions until just before use at each test. Out-of-date reagents must be discarded. Table 5.7 lists the water quality parameter and the best type of kit or methodology appropriate for that test.

Standard of chemical testing equipment

Notes:

1. All equipment needs to be checked and calibrated in accordance with the manufacturer's specifications and maintenance manuals.
2. Bleaching of DPD reagents occurs when free chlorine concentration is high and will give a false low reading. Follow the manufacturer's manual and dilute prior to testing if free chlorine is suspected of being higher than 5 mg/L.

Further information

The Public Swimming Pool and Spa Pool Advisory Document provides detailed explanations and information on disinfection, pool chemistry, risk assessment and other issues relevant to swimming pool operation.

Public swimming pool issues may be discussed with an environmental health officer at a local Public Health Unit by calling 1300 066 055, or at your local council.