Water boreholes are private water supplies which are used as an alternative to mains water and provide water for farming, irrigation, dairy, domestic use etc. Water from boreholes is of generally good quality, rocks act as natural filters and as water percolates through layers of soil and rocks, impurities are gradually removed by mechanical action as well as adsorption through the complex rock structure. However, water chemistry is complex and fractured rock formations can cause contaminants to enter the aquifer. Contaminants can also move into ground water through root systems, animal burrows, abandoned wells and other systems of holes and cracks that supply pathways for contaminants. Therefore, care must be taken before consuming water from boreholes and water should be tested for quality before domestic use or food contact.
Most microorganisms that contaminate ground water come from fecal matter from humans or animals. Contaminants like Cryptosporidium, Camplyobacter and E.coli can cause vomiting, diarrhoea or severe illnesses. A high percentage of outbreaks in the UK has been associated with private water supplies.
In recent years Defra have introduced new regulations and guidelines to ensure that water from private supplies is safe to drink. Following problems might be encountered when treating borehole water.
Sediment Removal from borehole water by Filtration
accuraMultiflow is an excellent sediment removal filter cartridge which is available in micron ratings of 0.5µ – 200µ. Graded density structure of this cartridge ensures high removal ratings and dirt holding capacity, providing a long service life.
If the water has high dirt loading then a bag filter from acuraBag filter range can be used as a pre filter to protect and increase life of sediment cartridge.
This combined filtration system can provide significant cost savings by increasing the life of filters and decreasing changeout frequency.
We can supply filtration systems from less than 1000 L/hr to 120,000 L/hr or more.
Cryptosporidium removal from borehole water by Filtration
Cryptosporidium are parasites which can cause diarrheal disease, cryptosporidiosis in humans. Cattle, sheep and human sewage are the main sources of contamination.
Coagulation, sedimentation and filtration are all effective in preventing contamination. It is important to note that Chlorine disinfection at the concentrations normally used for water treatment, is not considered effective for inactivating oocysts. Use of filtration before disinfection is more effective in the removal of Cryptosporidium.
Siga Filtration can offer cartridge filters suitable for the removal of Cryptosporidium. Please contact us for more information on this application.
Iron and Manganese removal from borehole water by Filtration
Percolating water through soil and rocks can dissolve minerals containing iron and manganese and hold them in solution.
Iron and manganese can be present either as particulate or in dissolved form in borehole water. These metals can interfere with the efficiency of water disinfection process by coating water treatment units. Iron can cause staining and give water a poor tasting metallic taste even though the water may look clear. These minerals can also react with beverages to produce black sludge.
Siga filtration can supply acuramultiflow or Pleat 2 filter cartridges for the removal of suspended iron and manganese. Dissolved Iron and Manganese can be removed by aeration followed by filtrtration as oxygen is required to oxidise iron and manganese into particles.
For more information on regulations affecting private water supplies
Defra (New Private Water Supply Regulations)
Summary of Private Water Supplies Regulations of 2009
Legislation – The Private Water Supplies Regulations 2009