To ensure the constant availability of accurate and up-to-date information about beach water quality, the water at every gazetted beach is sampled at least once a week during the swimming season and at least once a month at other times. Those beaches that stay open all year round are monitored weekly for the whole year. However, the EPD avoids creating specific monitoring ‘routines’, exactly because day-to-day use of beaches is not routine either. Instead, EPD staff collect samples on randomly selected days during the week, which can include weekends and public holidays.

[Image of water sampling in progress]

Beach water samples are collected for analysis by a team of trained inspectors who take the samples a short distance from the shore, standing in the water at a depth of from thigh to waist level. The samples are stored at 4 degrees Celsius until they are ready for testing. Staff also take samples from other water sources nearby, such as streams or drains, to get a sense of whether such external sources may have an impact on beach water quality.

[Image of operating a portable water analyser unit]

This is not the only role of the on-site sample collectors, however. They also record water temperature and measure the levels of dissolved oxygen in the water using a portable analyser unit. Weather conditions, and any other information that may affect the sample reading, is recorded too. All this data is input directly onto PDA units from which it can be uploaded directly to the EPD office server.

[Image of entering water quality data on site]

Beach monitoring frequencies

Beach Monitoring frequency Bathing season Non-bathing season Gazetted beaches open all year round* 4-6 times per month 4-6 times per month Other gazetted beaches 4-6 times per month At least once per month Non-gazetted beaches 2-3 times per month Once per month * Deep water Bay, Clear Water Bay Second, Silverstrand and Golden Beaches

After collection, beach water samples are brought to the EPD’s laboratory for analysis. The process is a relatively simple and reliable one. A portion of each sample is measured for pH, salinity and turbidity, while another portion is prepared for growing a culture of E. coli bacteria. To do this, the water sample is passed through a membrane to trap bacteria, and the membrane with its bacteria is then incubated for 18 to 24 hours. After this time, E. coli bacteria show up as green colonies on the membrane. The number of green colonies is then counted and their density calculated. Clearly, the lower the number for any given sample, the better the quality of the water.

The process of testing and analysing the water samples is relatively speedy at about one and a half days, which means the EPD can let the public know about health hazards or other water quality changes very fast.

[Image of analysing a water sample at the EPD laboratory]

[Image of E. coli colonies after incubation]

[Image of laboratory analysis of beach water samples]