Arsenic is semi-metal poison, which is used in rat poison.

Humans require extremely small amounts of Arsenic, which plays an important role in the integrity of the immune system, skin and hair.

Arsenic in Water

Arsenic occurs naturally in unpolluted water in concentrations as low as 0,010 mg/l.

Unpolluted groundwater from areas with naturally high Arsenic minerals can have Arsenic concentrations of as high as 0.500 mg/l.

Any higher concentration in any water source can be Arsenic pollution, which typically results from mining activities or pesticides in e.g. cattle dips.

What problems can Arsenic cause?

Arsenic poisoning is a chronic problem and the symptoms are skin lesions

The symptoms of acute arsenic poisoning can cause loss of sensitivity in the peripheral nerves as well as gastrointestinal symptoms.

Bathing in arsenic polluted water can cause health effects, since arsenic can be absorbed through the skin.

Children under the age of 2, people suffering from kidney diseases and people who consume large amounts of water, e.g. those living in hot conditions, are most sensitive to arsenic pollution.

Aesthetically arsenic in water cannot be detected by colour, taste and odour.

How can Arsenic in water be treated?

Arsenic in a pentavalent form (with a five-fold electronic charge) can be removed from water by flocculation, using ferric salts.

Arsenic in a trivalent form (with a three-fold electronic charge) needs to be oxidised before it can be treated with the flocculation method.

Any arsenic removal process requires skilled monitoring and analysis.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References - DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide

Cadmium is highly poisonous.

Cadmium is a soft metal, very similar to Zinc.

Cadmium is used in the galvanising process, which is used to protect other metals from corrosion.

Cadmium in Water

Cadmium occurs in natural, unpolluted water in concentrations of up to 0,001 mg/l.

Water contaminated by galvanising industries may have cadmium concentrations as high as 0.005 mg/l.

Water with cadmium concentrations higher than 0,005 mg/l, are rare and only occur where galvanised containers have been exposed to acidic liquids such as fruit juice, for long periods of time.

What problems can Cadmium cause?

Diagnosis of cadmium poisoning is very difficult, since the symptoms (nausea, and diarrhoea and vomiting) are indistinguishable from those of food poisoning.

Chronic health problems are kidney damage and aching bones.

Aesthetically, cadmium has no effects.  It has no odour, colour or taste.

People that are most sensitive to cadmium are those whose diet has a zinc shortage, heavy smokers and those that drink a lot of water whilst possibly living under hot condtions.

How can Cadmium in water be treated?

The normal purification method of flocculation with ferric salts, removes cadmium partially from water.

To remove all cadmium from water, the pH needs to be increased with lime, followed by settlement and filtration processes and finally returning the pH to its original state.

Skilled monitoring and operating are required to render cadmium removal processes effective

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Calcium is necessary to build and maintain a healthy skeleton.

When calcium oxidises, it dissolves in water and forms calcium hydroxide (slaked lime).

Drinking water that has calcium is good since it is a necessary dietary supplement.

Calcium in Water

When water has a calcium concentration of less than 10 mg/l, we say it is soft water and in such water soaps lathers easily.

When water has a calcium concentration of several hundred mg/l, we say it is hard water and such water causes soaps to flake and makes lathering difficult

What problems can Calcium cause?

Mostly calcium has a beneficial health effect, since large amounts of Ca are required for a healthy bone structure.

High Ca concentrations can however cause kidney stones in sensitive people.

People with kidney and gall bladder stones, as well as people that drink a lot of water under extremely warm conditions, are sensitive to high Ca concentrations.

Aesthetically, calcium in water is beneficial, since it makes water taste pleasant.  When it contains very high Ca concentrations, the water can taste “hard”.

High Ca concentrations in water can cause scaling and very low Ca concentrations can cause corrosion in distribution systems and appliances like washing machines and hot water cylinders.

How can Calcium in water be treated?

Methods for the removal of calcium from water are typically cation exchange (replace calcium with sodium) and demineralisation techniques, such as ion exchange or reverse osmosis.

Large amounts of water are treated by chemical precipitation and sedimentation.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References: DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Table salt comprises of a combination of sodium (Na) and chloride (Cl).   On its own, chloride is a negatively charged ion or anion.

High chloride concentrations in water make it taste more salty and cause increased corrosion of metals.

Chloride in Water

When the chloride concentration is less than 10 mg/l, we know that it is fresh water.

Higher concentrations of chloride are associated with salt pollution or marine intrusion.

Chloride concentrations of more than 700 mg/l are typical in arid regions, with saline soils.

What problems can Chloride cause?

Normal chloride concentrations in fresh water have no detrimental effects on your health.

When chloride concentrations exceed 1200 mg/l, it can disturb the salt/water balance in sensitive people and subsequently cause vomiting and nausea.

Aesthetically high chloride concentrations make water taste salty.

High concentrations of chloride in water can increase the rate of corrosion of iron in distribution systems and appliances, such as washing machines.

How can chloride in water be treated?

Chloride can be removed from water by using reverse osmosis, electro dialysis, distillation or resin-ion exchange demineralisation, all of which are expensive and energy-intensive.

All of the above processes are energy-intensive, require a high level of operator and maintenance skills and finally leaves us with concentrated brine, which is difficult to dispose of.

Suspended matter and hard water can easily foul these treatment processes.

Home treatment kits, using ion-exchange processes are available, but expensive and treat only small volumes of water.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Copper occurs in nature as an orange metal.

We need copper in our bodies as it forms an integral part of the fatty covering of nerve fibre sheaths.

Copper is useful in the electrical industry, since it is an excellent conductor of both heat and electricity.

Copper in Water

Copper occurs in natural, unpolluted water in concentrations of less than 0,1 mg/l.

Copper concentrations of more than 1 mg/l occur when the water has a relatively low pH and subsequently corrodes the copper from the water pipes in which it flows.  Such water has a blue-green colour.

What problems can Copper cause?

Copper concentrations in natural water usually have no adverse effects on healthy people.

People suffering from Will’s disease (a hereditary disease which can also be acquired from abnormally high iron intake, e.g. through beer brewed in cast-iron kettles) are however very sensitive to copper and can develop chronic health effects.  People that drink a lot of water, living under hot conditions, are also sensitive to copper.

Very high concentrations of copper can cause acute damage to the liver and kidneys with symptoms such as nausea and vomiting.

Aesthetically, higher copper concentrations can change the water colour to blue/green and subsequently stain clothes and hair.  The water can taste like metal as well.

How can Copper in water be treated?

In order to remove copper from water, you need a pH of between 6 and 7 and flocculate the copper, using aluminium and ferric salts.

Water with very high copper concentrations may need to be treated with lime and a precipitation method, whereby the copper is precipitated as copper hydroxide under alkaline conditions.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References: DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Fluoride is necessary in humans in minute quantities during tooth formation, to harden the tooth enamel.

Physically it is the most electro-negative element and therefore forms complexes with many metals.

Fluoride in Water

In unpolluted, natural, fresh water and unpolluted groundwater, fluoride concentrations can vary naturally between 0,1 and 0,3 mg/l.  Some groundwater can have a fluoride concentration of as high 12 mg/l.

What problems can Fluoride cause?

The intake of too high concentrations of fluoride over a long period of time can harden your skeleton to such an extent that your bones become brittle.  This in turn can lead to easy bone fracturing under mild strain and subsequent crippling.

Ingestion of high concentrations of fluoride can cause acute poisoning, with symptoms such as nausea, vomiting, abdominal pain, diarrhoea and convulsions.

Too much fluoride during your tooth forming years can cause discoloration of permanent teeth.

Fluoride in water has no taste, colour or smell and cannot be aesthetically detected, even in high concentrations.

Children under the age of 3 years, HIV positive people, people suffering from malnutrition, especially calcium and zinc deficiencies, people with liver or kidney disease, people who drink a lot of water and patients on renal dialysis, are all very susceptible to fluoride.

How can Fluoride in water be treated?

It is very difficult to remove low concentrations of fluoride from water.

Advanced technology is required for effective removal of fluoride from water.  Two processes include addition of activated alumina or bone char to absorb the fluoride, as well as desalination by means of ion-exchange resins.

Both of the above fluoride removal technologies require high levels of skill and maintenance.

Home treatment with clay or calcium carbonate chips will lower the concentration of fluoride in the water, but usually not even to optimum concentrations.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References: DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide

Iron is an important micro-nutrient, necessary in our bodies for forming haemoglobin (the red blood pigment, which carries oxygen).

Iron is a silvery-white metal, but due to oxidation, it normally appears to be brown or black.

We can recognise iron in the soil, when the soil has a reddish colour.

Iron in water

Iron occurs in natural fresh water because of leaching from iron-rich rocks or in anoxic, reducing sediments.

Normal concentrations in natural fresh water range from 0,001 to 0,5 mg/l.

Higher concentrations may be indicative of pollution. e.g. acid mine drainage.

What problems can Iron cause?

Healthy people with a balanced diet consume approximately 20 mg iron per day.

Water with an iron concentration of less than 10 mg/l has no adverse effect on your health.

Ingestion of excessive amounts of iron can lead to acute poisoning in babies and children.

Chronic iron poisoning over a long period of time, can lead to Will’s disease (Haemochromatosis).

Aesthetically iron can change the water colour to brown and make it taste like metal.

Children under the age of 4 and people that suffer from hypersensitivity to iron should be careful of high iron concentrations in water.

How can Iron in water be treated?

If the iron is uncomplexed as in water with low organic content, aeration of the water should be sufficient to precipitate the iron from the solution.

If the iron is complexed to organic matter in the water, strong chemical oxidants and lime will be necessary to remove the iron from the water.

Effective methods for the removal of iron from water are conventional coagulation and flocculation techniques.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References: DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Magnesium is necessary in the human body and plays an essential part in the functioning of the muscles.  The recommended daily magnesium requirement is 250 mg.

Physically, magnesium is an alkaline earth metal that burns with a brilliant light to form magnesium oxide.

Magnesium hydroxide is well known as the anti-acid solution, “Milk of Magnesia”.

Magnesium sulphate is well known as a purgative called “Epsom salts”.

Magnesium in water

If the magnesium concentration of water is less than 10 mg/l, it can be assumed that the water is fresh and unpolluted.

Some hard groundwater may have magnesium concentrations of several hundred mg/l.

What problems can Magnesium cause?

Magnesium can cause suppression of the central nervous system, when ingested in large amounts; however, this is very unlikely, since magnesium has a bitter taste.

Ingestion of a combination of magnesium and sulphate can result in diarrhoea.

When magnesium concentration of water exceeds 70mg/l, the water develops a bitter taste.

High concentrations of magnesium and calcium can cause scaling in distribution systems and appliances.

People that are sensitive to magnesium are children under the age of 1 year and people that consume large volumes of water.

How can Magnesium in water be treated?

Generally magnesium concentrations can be reduced in water by lime softening, followed by re-carbonation.

Other than these methods, ion exchange resins or precipitation of magnesium at high pH are also effective in reducing the magnesium concentrations.

All methods used to remove magnesium from water require skilled operation and maintenance.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Manganese is a metal that occurs in soils that are often associated with water, giving the water it a tea-like colour.

Tea-coloured water in the Western and South Cape regions are due to the presence of organic matter and manganese.

Manganese occurs naturally in tea.

Manganese is essential in the human body, where it plays an important role in cartilage integrity.

Manganese in water

Unpolluted, fresh water has a manganese concentration of as much as 3 mg/l.

As soon as the manganese of a water source exceeds 5 mg/l, it can be assumed that the water is either polluted or manganese was circulated to the surface from the bottom of the water source.

What problems can Manganese cause?

Ingestion of less than 2 mg manganese per day is normal and will have no adverse affects on the human health.

When the human being is exposed to high levels of manganese over a long period, it may cause brain damage, resulting in a Parkinson-like disease.

Manganese concentrations in water rarely cause any health effects.

Children under the age of 3 years, kidney patients and people that drink large volumes of water are most sensitive to manganese.

How can Manganese water be treated?

Generally magnesium concentrations can be reduced in water by lime softening, Processes for the removal of manganese are aeration, chemical oxidation (strong oxidants are required) and lime treatment, followed by flocculation and filtration.

Aeration or alkalinisation is only effective when the water is free of organic matter and the manganese uncomplexed (which is seldom).

Treatment with domestic bleach will improve the water quality, but will fail to remove manganese.

Home treatment kits, usin ion-exchange processes are expensive and treat only small volumes of water.

How can Manganese water be treated?

Generally magnesium concentrations can be reduced in water by lime softening, Processes for the removal of manganese are aeration, chemical oxidation (strong oxidants are required) and lime treatment, followed by flocculation and filtration.

Aeration  or alkanlinisation is only effective when the water is free of organice matter and the manganese uncomplexed (which is seldom).

Treatment with  domestic bleach will improve the water quality, but will fail to remove manganese.

Home treatment kits, using ion-exchange processes  are expensive and treat only small volumes of water.

 References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Nitrate (NO₃) is formed when Ammonia (NH₄) and Nitrite (NO₂) are oxidised.

Nitrate and nitrite can be easily converted from the one to the other.

Nitrate is an important plant nutrient.

Nitrate is produced during the decaying process of plants as well as animal and human wastes.

Ntrate/Nitrite in water

The nitrate concentration of fresh, unpolluted water is normally less than 2 mg/l.

The concentration of nitrates in ground water can be as high as 20 mg/l.

Higher concentrations of nitrate can be indicative of pollution from e.g. agricultural land use activities.

What problems can nitrate cause?

Nitrate can be the reason for chronic fatigue and failure to thrive in humans.

Bottle fed babies under the age of one year can suffer from cyanosis (blue discoloration of skin and mucous membranes due to inadequate oxygenation of the blood) and experience difficulty in breathing.  This situation occurs when nitrate is reduced to nitrite.  The nitrite then forms a complex with the red blood pigment, haemoglobin, forming methaemoglobin, when the intestinal flora is abnormal.  This is usually the case with malnourished babies who have iron anaemia deficiency and a vitamin C deficiency.

Children under the age of 3 years, kidney patients and people that drink large volumes of water are most sensitive to manganese.

How can Nitrate in water be treated?

Processes used to remove nitrates from water are ion-exchange, reverse osmosis, denitrification (biological reduction with carbon).

All of the above processes are used for large volumes of water, but they are difficult to maintain and optimise and require advanced and intensive supervision.

Nitrate is difficult to remove from water and since it stimulates algal growth, secondary treatment processes may be necessary.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Potassium is an essential substance of the human diet.

It is an important cation in all-living tissue.

Potassium is an alkali metal.

Potassium in water

Normal levels of potassium in unpolluted, fresh water are between 2 and 5 mg/l.

Higher levels are indicative of pollution possibly from runoff from agricultural irrigation, fertiliser-producing industries and even from domestic wastes.

What problems can Potassium cause?

Acute exposure to high concentrations of potassium, can cause:

    ~Interference with heart muscle funciton.

    ~Interference with normal muscle function.

    ~Irritation of mucous membranes.

    ~Nausea and vomiting.

Children under the age of 2 years and kidney patients are at risk to be affected by higher than normal potassium levels.

High concentrations of potassium can impart a bitter taste to waste.

Potassium is colourless and odourless and therefore has no adverse effect on the appearance and smell of water.

How can Potassium in water be treated?

Processes used for the removal of potassium from water, are desalination processes, such as:

   ~Reverse osmosis

   ~Ion-exchange demineralisation, using mixed bed resin.

   ~Distillation.

All removal processes are difficult and require highly skilled operation and maintenance.

All processes produce a waste stream, which are difficult to dispose of.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References: DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guid

Sodium is an important dietary constituent, which is necessary to maintain the electrolyte balance in the body.

Sodium is an alkali metal.

Sodium is one of the 2 parts of ordinary table salt or sodium chloride (NaCl₂).

Sodium in water

Sodium concentrations in water can vary from less than 50 mg/l in regions with high rainfall, to 500 mg/l in arid regions.

The sodium concentration in seawater is 11 000 mg/l.

Higher sodium concentrations are found naturally in ground and surface waters of the Western and Southern Cape, as well as in some mine waters.

What problems can Sodium cause?

Excessive intake of high concentrations of sodium can put pressure on the renal and cardiac systems.

It can also cause disturbances in the salt balance of the body.

Children under the age of 2 years, people with water retention problems and people who drink large volumes of water are at risk to develop serious health problems from excessive sodium intake.

If sodium is present in fresh water along with chloride (sodium chloride), the water taste salty.

How can Sodium in water be treated?

Sodium can be removed from water, by the following desalination processes:

   ~Reverse osmosis

   ~Electro dialysis

   ~Ion-exchange demineralisation

   ~Distillation

All of the above treatment processes require a high level of operator skills and maintenance.

These processes can easily fail because of suspended matter and scaling, which can occur in hard water.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Magnesium sulphate is better known as the purgative, “Epsom salts”.

Sulphate is the oxi-anion of sulphur.

Sulphate in water

If the sulphate concentration in a water source is less than 10 mg/l, it is an indication that the water source is fresh and unpolluted.

Higher levels of sulphate in any water source can be indicative of some form of pollution.

Typical pollution sources are mine drainage and effluent return flows, which can contain sulphate concentrations of as high as 500 mg/l.

What problems can sulphate cause?

When new water users (new residents or travellers) are initially exposed to higher levels of sulphate in drinking water, it can have adverse health effects, causing diarrhoea.  Adaptation after prolonged exposure can take place.

Aesthetically elevated sulphate levels in water can impart a bitter, astringent taste and a “rotten egg” smell to water.

High sulphate concentrations in water can accelerate corrosion of metals, especially iron.

Children under the age of 2 years, water users or travellers and people who drink large volumes of water can be at risk and suffer from adverse health effects, such as “Traveller’s diarrhoea”.

How can Sulphate in water be treated?

Sulphate removal from water can be done by means of the following processes:

   ~Ion exchange with a resin.

   ~Precipitation with salts of calcium, followed by settlement and filtration.

   ~Desalination processes, such as ion-exchange demineralisation, reverse osmosis or distillation.

All of the above treatment processes require a high level of operator and maintenance skills.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Total hardness can be expressed as the sum of calcium and magnesium concentrations, expressed as mg/l calcium carbonate (CaCO­₃) and is calculated by means of the following formula:

        T.H. = [2,497 x calcium (mg/l))] + [4.118 x magnesium (mg/l)]

Total Hardness in water

The total hardness of water is the value that indicates how easy or difficult soap can lather in the water.

When the total hardness of water is low, the water is referred to as fresh, soft water, containing very low concentrations of calcium and magnesium e.g. rainwater.

When the total hardness of water is high, the water is referred to as hard water, containing high concentrations of soluble calcium and magnesium, e.g. some groundwater.

What problems can Total Hardness cause?

Total hardness, in some cases is beneficial for your health, contributing to your daily allowance of the calcium and magnesium

Sensitive people, like those with a history of kidney or gall-bladder stones and children under the age of 1 year, should avoid hard water.

Elevated total hardness changes the taste of water, especially when preparing coffee or tea and it impairs the lather ability of soap.

Elevated total hardness causes scaling problems in pipes and appliances.

Lowered total hardness (soft water) causes corrosion problems in pipelines and appliances

How can Total Hardness in water be treated?

Water can be softened by cation exchange and mixed-bed-ion-exchange desalination to demineralise the water.

Any demineralisation technique will decrease the total hardness.

For large volumes of water the accepted techniques are precipitation and sedimentation.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References: DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Zinc is an essential nutrient, playing an important role in a healthy skin and the formation of cell membranes, as well as in the immune system.

Zinc is a grey metal, which is relatively resistant to corrosion.

Zinc is utilised in galvanising industries to protect iron from corrosion.

Zinc in water

When a water source has a zinc concentration of approximately 0,015 mg/l, it is an indication that the water source is fresh and unpolluted.

Higher zinc levels can be an indication of zinc pollution, from e.g. industrial processes of zinc leaching into the ground water.

What problems can Zinc cause?

Normal levels of zinc in unpolluted water have no adverse health effect on the human body.

Zinc concentrations of more than 20 mg/l can cause nausea and vomiting in children under the age of 2, people receiving chemotherapy and people that consume large volumes of water.

Elevated levels of zinc in water can impart a bitter, metallic taste to water.

Water with zinc concentrations exceeding 5 mg/l can have a milky appearance.

How can Zinc be treated?

Zinc is removed from water by raising the pH to between 9,5 and 10, under which circumstances the zinc will precipitate as zinc hydroxide.  The latter can be removed from the water by means of settlement and filtration, followed by readjusting the pH with a suitable acid.

Zinc removal from water is usually very easy, the most difficult part being the accurate readjustment of the pH in the end.

Home treatment kits, using ion-exchange processes are expensive and treat only small volumes of water.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Conductivity is a measurement of the ability of the water to conduct electricity.

What does Electrical Conductivity indicate?

The EC of distilled water is low as opposed to seawater, with a high EC.

The EC (measured in mS/m) of water indicates whether the water is fresh or saline.

Rainwater has an EC of less than 1 mS/m.

EC indicates where the water originates from, e.g. if water travelled over granite, it has an EC of around 5 mS/m.  Water that travelled over sedimentary rocks usually has a much higher EC, ranging from 30 to 170 mS/m.

Climate can increase the EC, by concentrating the salts during droughts.

Electrical conductivity is indicative of the total dissolved solids (TDS, measured in mg/l) in the water.

One can determine the approximate TDS value of water by multiplying the EC with 6,5 i.e.:

          TDS = EC x 6,5

What problems can Electrical Conductivity cause?

The following health problems can occur where the EC exceeds 370 mS/m:

   ~Disturbance of the salt and water balance in children.

   ~In the blood pressure of heart patients and renal patients.

   ~Laxative effects when sulphate concentrations are high.

Aesthetic problems of water with an EC as high as 150 mS/m, fail to quench thirst.

Sensitive groups are children under the age of 1 year, patients on salt-restricted diets such as heart and kidney patients and individuals with chronic diarrhoea.

How can Electrical Conductivity in water be treated?

The water pH can be increased with the addition of alkaline reagents, such as lime, sodium hydroxide or sodium carbonate.

The water pH can be decreased with the addition of acidic reagents, such as sulphuric or hydrochloric acid or it can be done by the addition of carbon dioxide, which forms carbonic acid when it reacts with water.

Chemical adjustment of water pH, will increase the salinity of the water, thus care should be taken not to overdose the water with chemicals

References: DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

pH is an indication of the hydrogen ion concentration in water, which reflects the acidity (pH less than 7) or alkalinity (pH greater than 7) of the water.

Exceptions exist in the Southern and Western Cape, where the natural water has a low pH.

When the pH is lower than 7, the pollution source is acidification processes, like we find in acid mine drainage, where the pH can be as low as 3,0.

On the other hand pH values higher than 8,5 are indicative of an alkaline pollution source.

What does pH indicate?

pH can indicate whether water is polluted or not.  In unpolluted water, the pH ranges from 6,5 to 8,5.

Exceptions exist in the Southern and Western Cape, where the natural water has a low pH.

When the pH is lower than 7, the pollution source is acidification processes, like we find in acid mine drainage, where the pH can be as low as 3,0

On the other hand pH values higher than 8,5 are indicative of an alkaline pollution source.

What problem can pH cause?

Direct health problems caused by pH extremes are the irritation or burning effects on the mucous membranes.

Indirect health effects are the long-term effect of corroded eating utensils and water containers on the water users.

The aesthetic effect of water with a high pH is a soapy taste and with a low pH it is a sour taste.

Sensitive groups are individuals with sensitive skin or with skin problems.

How can pH in water be treated?

The water pH can be increased with the addition of alkaline reagents, such as lime, sodium hydroxide or sodium carbonate.

The water pH can be decreased with the addition of acidic reagents, such as sulphuric or hydrochloric acid or it can be done by the addition of carbon dioxide, which forms carbonic acid when it reacts with water.

Chemical adjustment of water pH, will increase the salinity of the water, thus care should be taken not to overdose the water with chemicals.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Turbidity is the light-scattering ability of water, measuring the cloudiness or the muddiness of the water.

It is caused by the presence of suspended solid matter.

Suspended solid matter consists or inorganic matter (clay particles) or organic matter (detritus or living organisms).

Turbidity is measured in NTU (Nephelometric Turbidity Units).

What does Turbidity indicate?

Crystal clear water has a very low turbidity.

Any increase in the muddiness of water causes and increase in the turbidity.

Turbidity in clean spring and ground water can be as low as less than 1 NTU

Turbidity in mud-laden surface waters can be as high as thousands of NTU’s

After a storm with heavy rainfall, the turbidity is usually much higher due to erosion and the presence of washed away surface water.

What problems can Turbidity cause?

Turbidity itself does not have any health risks for people.

Turbidity is an indicator of microbiological water quality, since the surfaces of suspended particles increase the adherence possibilities for micro-organisms.  Thus to properly disinfect water, all the suspended solids must be removed.

Turbidity aesthetically makes the water look cloudy or dirty and the water may taste like mud too.

People sensitive to turbidity will be children under the age of 2 years.

How can Turbidity in water be treated?

Treatment processes like purification, flocculation and filtrated are hampered by excessive turbidity, subsequently making it difficult to disinfect the water properly.

Chlorination of turbid water can lead to an increase in trihalomethane (THM) in the water.  Therefore it is important to choose the treatment process according to the degree of turbidity.

The most common processes used for decreasing turbidity, are flocculation, settlement and filtration, but when turbidity peaks, the processes must be adapted accordingly.

Home treatment by means of filtration kits is only adequate for small quantities of water.

References: DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Faecal coliforms are bacteria that are used as an indicator of faecal pollution.

Their habitat is the digestive system of any warm-blooded animal, humans included.

Faecal Coliforms in Water

When faecal coliforms are found in any water source, it indicates that the water is polluted with human or animal excretion.

By counting the number of faecal coliforms in a water sample, we can determine to what degree the water is contaminated and what type of water source it is.

In uncontaminated deeper groundwater, there may be no coliforms.

In clean, natural surface water, the count can be between 1 and 10 per 100 ml.

The faecal coliform count in raw sewage is more than several millions per 100 ml.

Depending on the degree of pollution, polluted surface water can carry a count of between 10 and several millions faecal coliforms per 100 ml.

What problems can Faecal Coliforms cause?

Health problems:

   ~The presence of a specific number of coliforms, indicate the possible presence of other disease-causing micro-organisms, such as protozoa, bacteria, parasites or   viruses, which can cause several gastro-intestinal diseases.

   ~The main symptoms of these diseases are diarrhoea and fever, which usually cause dehydration and if untreated can be fatal.

   ~Sensitive groups are HIV positive people, children under the age of two or any person whose immune system is compromised by e.g. chemotherapy.

Faecal coliforms on their own have no aesthetic effect.

How can Faecal Coliforms in Water be treated?

Water can be treated by the following methods:

   ~To reduce the faecal coliform counts, treatments such as flocculation, coagulation and filtration are adequate.

   ~For total removal of faecal coliform, the water can be treated chemically (chlorination) or physically (ultra-filtration or UV light).

   ~Home treatments, such as adding 1 teaspoon of bleach to 20 litres of water and waiting for at least 30 minutes or boiling the water for 20 minutes, can be used in case of an emergency. If water is turbid, the bacteria can survive the treatment within suspended matter.

   ~To maintain disinfection in the distribution system, the free available chlorine concentration must be maintained at 0,2 to 0,5 mg per litre.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Free available chlorine is the free chlorine concentration that remains in the water for 30 minutes after breakpoint disinfection.

Free Available Chlorine in Water

When there is a free available chlorine concentration remaining after a disinfection process, we know that the disinfection was efficient and we know that the water is free of any microbes.

If free available chlorine is present in any water source, it is indicative of treated water, since it does not occur in natural waters.

What problems can Free Available Chlorine cause?

Health problems:

   ~The absence of free available chlorine after treatment can cause health problems, since it shows that the disinfection was not done or that it was insufficient and microbiological infections can still take place.

   ~If the residual chlorine is present in the allowed concentrations, it can prevent secondary infection of a treated water source, thus rendering the water safe.

   ~If the residual chlorine is too high, it can cause mucous membrane irritation, nausea and vomiting.

     Sensitive groups are children under the age of two or any person with sensitive skins or allergies.

From an aesthetic point of view, too high concentrations of residual chlorine can cause the water to be unpalatable, tasting and smelling of disinfectant.

One can never achieve Blue water status with chlorine treated water.

How can Free Available Chlorine in water be treated?

Where the free available chlorine concentrations are too high, the water can be treated in the following ways:

   ~Better chlorination process control i.e. not using too high a dosage of chlorine.

   ~Removal of free available chlorine by using activated carbon.

   ~Reducing the free available chlorine concentration by boiling it or by storing the water in covered containers.

   ~Carbon filtering will also remove the chlorine taste of water.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.

Total coliforms refer to the total bacterial count in water, which includes faecal coliforms as well as other bacteria.

Total Coliforms in water

Total coliforms indicate hygienic quality of the water.

   ~In uncontaminated deeper groundwater, there may be no coliforms.

   ~Where pit latrines are in use, the total coliform counts may be high.

   ~In clean, natural surface water, the count can be between 1 and 10 per 100 ml.

   ~The total coliform count in raw sewage is more than several millions per 100 ml.

   ~Polluted surface water can carry a count of between 100 and 100 000 total coliforms per 100 ml.

What problems can Total Coliforms cause?

Health problems:

   ~The presence of a specific number of coliforms, indicate the possible presence of other disease-causing micro-organsisms, such as protozoa, bacteria, parasites or viruses, which can cause several gastro-interstinal diseases.

   ~The main sumptoms of these diseases are diarrhoea and fever, which usually cause dehydration and if untreated can be fatal.

   ~Sensitive groups are HIV positive people, children under the age of two or any person whose immune system is compromised by e.g chemotherapy.

How can Total Coliforms in water be treated?

Water can be treated by the following methods:

  ~To reduce the total coliform counts, treatments such as flocculation, coagulation and filtration are adequate.

  ~For total removal of total coliform, the water can be treated chemically (chlorination) or physically (ultra-filtration or UV light).

  ~Home treatments, such as adding 1 teaspoon of bleach to 20 litres of water and waiting for at least 30 minutes or boiling the water for 20 minutes, can be used in case of an emergency. If water is turbid, the bacteria can survive the treatment within suspended matter.

References:  DWAF (2001). Quality of domestic water supplies. Vol. 1. Assessment guide.