Many boreholes in South Africa have a certain level of iron and manganese in them. Iron bacteria feed off this iron and manganese, using them as energy sources. These bacteria are found on surface water and in the soil and can easily infiltrate your borehole. Iron bacteria themselves are not harmful to humans but contamination can create a water quality environment suitable for disease-causing, or pathogenic, bacteria, viruses and other microbes. Moreover, they can also cause some unpleasant and persistent plumbing related problems as well as;
- Unpleasant taste and odours,
- Rusty slime build up, called biofilm, in your borehole, tank or filters,
- Reduced well production or reduced efficiency of point of use treatment devices,
- Premature or excessive corrosion of borehole and plumbing components.
Biofilm is the reddish-brown slime that builds up inside your borehole and causes the problems listed above. It is the metabolic byproduct from the oxidation of iron or manganese by the bacteria. If left unchecked, biofouling can clog pump intakes, well screens, filters, and water pipes.
Stains, tastes, or odours may be due to other causes, so it is imperative to identify the chemical substances and microorganisms borehole water. For this we would take a sample of the borehole water and send it to the laboratory for analysis. From there we can gauge what organism is causing the problem and how it should be treated. The World Health Organisation (WHO) recommends that the iron (Fe) and Maganese (Mn) levels in the borehole should be 0.3 mg/l to 0.1mg/l.
To remove this slime and iron bacteria from the borehole we use a chlorine based shock treatment. The added benefit of this treatment is that it will reduce other pathogenic microorganisms, sometimes harmful, that may also be present in your drinking water. To determine the extent of the problem we will put a borehole camera down the hole and then treat as per our observations. During this time of super chlorination the water must not be used at all.
Borehole clogging in the water supply system is of greatest concern as it jeopardises the sustainability of the borehole. Often owners will make the erroneous assumption that the borehole is slowing down or has run dry where in fact it is the build up of biofilm which is impeding the flow of water into the borehole. Having your borehole serviced at regular intervals can save you from having to drill a new borehole.
The reduced production capacity lowers the efficiency of the borehole. As a result the electricity costs increase due the higher electricity requirements for pumping. This is because the pump needs to work harder and hence uses more electricity. There is also more wear on the pump reducing its longevity. The biofilm also builds up in pumps and begins to clog the impellers which can then result in pump failure. Furthermore, with the presence of sediment or biofilm in the water your ultra violet light filter will become increasingly ineffective. The time period between cartridge changes in your filter housing will also decrease thereby increasing the cost of using borehole water.
A borehole should be maintained or serviced in the following circumstances:
- Every two to three years depending on the results of your water quality test,
- If you have moved to a property that has a borehole and the old owner does not have sufficient knowledge of the borehole performance,
- The borehole water is turbid, which means it is cloudy or has suspended particles in it,
- There has been a decrease in the borehole’s performance capacity—that is, the litres of water per minute (hour) that the pump can supply decreases,
- The water has developed an odour or taste problem,
- The water tests positive for total coliform and/or overall biological activity,
- If you have a high iron content in your water. This will be picked up in the water quality test,
- If you have reoccurring problems with your borehole pump.
The cleaning process of a borehole basically requires two methods; either chemical or mechanical and in some cases both methods need to be used. A chlorine based solution is usually used in the chemical method. In the case of the mechanical methods the hole can be water jetted or brushed to remove the build up along the walls of the borehole and/or pumped to remove sand, sediment or other debris. A professional assessment needs to be done in order to determine the course of the rehabilitation or cleaning of the borehole.
For more information please contact Betty 083 446 4226