Water treatment myths busted

Ekurhuleni consumers recently experienced an unusual odour in their water, often perceived as a taste, which was caused by a harmless substance called geosmin.

Following the publishing of an article about geosmin by the GCN, Rand Water invited us to their offices in Glenvista, south of Johannesburg to learn more about geosmin, home treatment devices and water purification.

Geosmin is an organic compound made up of a type of actinobacteria found in surface water.

Due to the increased densities of blue-green algae which occur on the Vaal Dam – the source of water for Rand Water – during the hot summer months, the odour tends to intensify.

In our article we reported that those sensitive to the taste could take the following measures to minimise the effect of geosmin:

• Use a carbon filter. While the filter may not eliminate the taste entirely, using one can improve the flavour and make water more palatable.

• Invest in a reverse-osmosis water-treatment system; this is the most effective system for removing all geosmin from the water.

• Cool your water in the fridge. The colder water will make your taste buds less receptive to the flavour of geosmin.

Karl Lubout, microbiologist and water quality specialist at Rand Water, gave some insight on the current trend of consumers buying home treatment devices to decrease the odour of geosmin in their water.

“When you tell consumers to use these water treating systems, you find that a lot of water is being wasted.

“With reverse-osmosis you put water under pressure through a pore-sized membrane, and what you get out on the other side is something very close to distilled water,” Lubout said.

Most of these purification systems, including those using reverse-osmosis, leave the consumer with water lacking in minerals as the water is distilled. In addition, if not maintained properly, bacteria may start growing inside their devices, leaving the water it produces contaminated.

“We do not necessarily support the use of these devices because, as it removes impurities, that means water is wasted in the process,” Lubout said.

“You find that 70 to 80 per cent of water is wasted during these processes, consumers will need high-pressure pumps, and it is expensive.”

The other home treatment device they touched on was the use of ‘carbon filters’.

“Marketers of this specific device will use what they call a ‘jam jar test’,” Lubout explained.

“They pour your tap water into a jam jar, and they put an aluminium electrode and an iron electrode into the jam jar and then an electric current over the two electrodes.

“The water will either foam or turn black, and all that proves is that any water will conduct a current.

“And then marketers will say, ‘look at how dirty this water is’.”

“The tap water we provide contains mineral content which consumers need on a daily basis, such as calcium and magnesium,” Lubout said.

“When you see the water changing colour from the electrodes, it is the minerals reacting to it.”

Yvonne Liee, senior water quality advisor at Rand Water, explained further: “When marketers conduct these demonstrations they use their own water from the reverse-osmosis system. Because the water lacks minerals, it will not react to the current.

“We advise consumers to invite the marketers again, take a pinch of salt and add it to their distilled water during their demonstration, and because salt is sodium chloride it is going to react the same as the tap water.”

Although water treatment devices may seem effective and viable, Rand Water firmly believes that to own and maintain these devices is expensive, that consumers may waste more water than they’re consuming, and that high-pressure pumps are needed for the systems.

Where distilled water from these treatment systems can be beneficial is in cases of people who react to certain minerals in water, in laboratory tests, and in areas where toxins are regularly found in water.

“People always associate an odour with health hazards, and because of this we are aware of the geosmin reactions and we seek to better educate our consumers on water treatment devices and purification,” Liee added

Consumers are further assured that they do not need to run further tests on water in their households, as this is unnecessary and they may end up doing more harm than good to their health.

“We supply water to over 12-million people,” said Labout. “For us it is very important that our quality assurance is right, and we know for a fact that our water meets all the necessary requirements.”

Rand Water advised that the most cost-effective remedy for consumers sensitive to the odour is to keep the water refrigerated or keep it in an open container for a few minutes until the odour evaporates.

For further updates on the water quality in your area, visit www.reservoir.co.za

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