Making sense of borehole water tests PDF Print E-mail
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Monday, 12 December 2016 13:34
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Many people have their borehole water tested and get a test certificate with figures on it that mean nothing to them. We asked Nici Jooste, laboratory manager at the Boschkop-based West-Bio Chemical services testing laboratory, to explain exactly what is tested and why.

Nici Jooste

When you buy a property that makes use of borehole water, financial institutions require the seller to provide them with water test results, done by a certified laboratory.

In reality there is no such thing in nature as pure water. Nearly all water contains contaminants, even when there is an absence of nearby pollution-causing activities. It is merely the level of contamination that affects the water quality and the purpose for which it could be used.

An example of natural water contamination is the mineral fluorspar that occurs in rock and soil in many areas and can lead to excessive fluorine in the water taken from boreholes. Chronic fluoride poisoning causes various forms of ill health, such as joint stiffness, brittle bone and discoloration of developing teeth.

Pesticide residue and industrial pollution in drinking water is a constant problem. Many dissolved minerals, organic compounds and microbes find their way into your drinking water from the air and soil.
Water quality refers to chemical, physical, biological and radiological characteristics of water. It is most frequently used by reference to a set of standards against which compliance can be assessed.

The SABS standard SANS 241 is a document that outlines the quality of acceptable drinking water, which is used by testing laboratories as a guideline. However, this standard yields an extensive list of potential water contaminants, and it will be very costly to test for all of them.

The testing laboratory will advise you on several analytical tests that will reveal the severity of specific impurities and indicate the likely presence of other contaminants. It is advised to test at least the following annually: pH, total coliform bacteria and E Coli, nitrates, total dissolved solids, fluoride and organic carbon contaminants.

Low pH (a measure of how acidic the water is) can lead to corrosion of plumbing and water supply, such as copper and lead, which may dissolve and reach unhealthy levels.

High nitrate levels usually indicate contamination by drainage and can convey other harmful pollutants such as pesticides. High nitrate levels have a severe toxic effect on infants, because excess levels can cause methemoglobinemia or blue baby disease.

Electrical conductivity and total dissolved solids are tested to establish the approximate mineral salt content. If this value is too high, the water will not necessarily quench your thirst. You can look at the turbidity and colour of the water and faecal coliforms (possible presence of faecal matter).

Chloride and sulphate both occur in hot dry areas and can cause nausea and vomiting at very high levels. Arsenic, common in mining areas, is also tested.

Less frequently found are elements such as cadmium and copper. Copper has an effect on the colour of the water, normally at low pH levels.

Substances tested that occur more commonly in water and may have aesthetic or financial concerns in domestic water use include manganese, zinc, iron, potassium, magnesium and calcium.

Manganese is the common reason for brown discolouration in sinks and basins. Iron, sodium, potassium and magnesium affect the taste of the water. Calcium can be the cause of scaling and indicates the hardness of water.

 

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