On its own, water quality sampling cannot provide timely information about water quality conditions because the water quality at beaches can change faster than the sampling frequency (weekly) and the analysis time (it can take up to 48 hours from the time a sample is taken to get the test result).

Nevertheless, water quality sampling continues to be an essential component of the Safeswim programme. Sampling data is used to develop water quality models and ongoing sampling is critical to allow the performance of models to be assessed and support the refinement and improvement of models.

Safeswim’s sampling programme comprises:

• A record of samples taken at each location in the programme (usually a minimum of three years of samples and going back over 20 years in some locations).
• Ongoing regular year-round sampling at each site in the programme.
• Targeted sampling at sites during heavy, moderate, and light rainfall.
• Community-led sampling.

After switching to a ‘sampling and modelling’ approach in the 2017/18 summer, Auckland Council has collected several thousand water quality samples per year at up to 244 sites (some of these not yet on Safeswim) around the Auckland region, with over 6,000 samples collected over the 2023/24 summer swim season. This is far greater than the volume of samples that would be collected under a weekly sampling programme.