Faster, easier way to test water quality

Anew water test, developed by the Council for Scientific and Industrial Research (CSIR), could be an important tool in the fight to improve SA’s water quality.

Despite the country’s water scarcity, waste water pumped into the rivers and dams is often not clean enough, polluting this increasingly scarce resource.

According to the latest Green Drop Report, which measures the health of the country’s waste water infrastructure, more than 80% of SA’s waste-water treatment facilities are not functioning properly. Only 135 of the 824 waste-water treatment facilities are functioning well.

This means that human effluent and waste are entering the country’s water systems, threatening the health and livelihood of people who depend on rivers and dams for potable water or for irrigation.

A common bacteria associated with waste-contaminated water is Escherichia coli (E Coli). Although many strains are harmless, some can lead to serious food poisoning, according to the World Health Organisation. This is a particular danger for children, the elderly and people who are immunocompromised.

“Discharged effluent of poor water quality not only places strain on the environment and a scarce natural resource, but also increases the risk for spread of diseases through water-borne contaminants,” says Dr Kevin Land, CSIR group leader for the project.

Testing water for pathogens such as E Coli is difficult. “Current methods of detecting pathogens in water are neither simple nor portable,” Land says.

Water samples need to be incubated for 18-24 hours, with the whole process usually requiring one to five days.

Traditional tests are “expensive and require well-equipped laboratories employing trained technicians”. These kinds of facilities are usually centralised, which means that water from rural areas — which is where a lot of the problems are — take even longer to test.

“The slow turnaround time in obtaining results for water testing affects service delivery and the operational management of water-treatment plants,” Land says.

The CSIR’s rapid test, known as ColiSpot, can test for E Coli within a day, says Klariska Moodley, a senior research engineer and project manager at the CSIR.

The ColiSpot system consists of a flow test, which is similar to a home pregnancy test, a filter and incubation gear, which includes an oven and nutrients to grow bacteria.

BACTERIAL GROWTH

The water sample is filtered and if there are bacteria present, they collect in the filter membrane. The membrane is placed in a petri dish that contains nutrients to promote the growth of any possible bacteria and then baked in an oven.

After six hours, you can test for the presence of E Coli, says Moodley. Like a pregnancy test, the flow test shows two red lines if there is E Coli.

Catherine Ritchie, communications manager for the Wildlife and Environment Society of SA, welcomes the innovation.

She says results for municipal Blue Drop, or potable water quality, and Green Drop (sewerage outflow water quality) are falling across the country.

“This could worry all citizens and businesses using water resources,” Ritchie says.

“Concerned citizens can use this tool to proactively engage with their local councillors and municipal and Department of Water and Sanitation officials to draw attention to and collectively address local water quality concerns.”

Moodley says the technology has been tested in the field at the Tshwane waste water treatment works for more than eight months, where it has been used as an early warning system for possible contaminants.

“We aim to keep the cost of the test below R50 a sample, but when large-scale manufacturing is taken into account, this price could be further reduced,” Moodley says.

The CSIR is in discussions with potential manufacturers.

The next step in the project is to make it as user-friendly as possible, mainly through further automation, which could also speed up the time taken to test a sample, Moodley says.

Neither the national Department of Water and Sanitation nor the City of Tshwane had responded to questions at the time of publication.