Preventive Checking preventive measures Corrective action Causes measures What to check Signs that action is needed Event: FILTER NOT REMOVING PARTICLES DOWN TO 2 m IN SIZE – cont’d C1.5.4 Regularly Flow rate. Pressure Wash the filter replace filter difference is lower cartridge and Cartridge Difference cartridges, and than usual, or flow flush to waste failure. between the wash pre-filters. is higher than until checks pressure before Note the date usual. show that the filter and and what is particle after the filter. Cloudiness in the done. removal is (Sudden water following again effective. Before buying changes in flow filtration. new cartridges or the pressure Get another Customer check they have difference may batch of complaints. certificates indicate filter or cartridges. showing they pre-filter failure.) Cases of diarrhoea Consider meet in people drinking Performance changing filter specifications. the water. certificates. supplier. Records not kept. C1.5.5 Disinfect filter Test the water Disinfectant Continue housing when leaving the filter concentration not flushing until the Contamination installing the for the reduced to an disinfectant of filter housing cartridge, and disinfectant.6 acceptable level. cannot be when changing flush to waste to detected. the cartridge. Customer remove residual complaints. Train staff if disinfectant. necessary. Cases of diarrhoea Make sure the in people drinking person replacing the water. the cartridges knows the correct way to do it to avoid contamination. C1.5.6 Keep flow rate Flow rate. Flow too high. Reduce flow to less than the within Flow too high Cloudiness in the maximum the specifications. for cartridge water following filter can handle. design. filtration. Customer complaints. Cases of diarrhoea in people drinking the water. 6 If household bleach (chlorine) is used to disinfect the filter housing, chlorine test tablets from a swimming pool test kit can be used for this. They turn pink when there is chlorine in the water. Use 1 tablet in 10ml of water; a slight pink colour indicates that the chlorine concentration is acceptable.
Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed Event: FILTER NOT REMOVING PARTICLES DOWN TO 2 m IN SIZE – cont’d C1.5.4 Cartridge failure. Regularly replace filter cartridges, and wash pre-filters. Note the date and what is done. Before buying new cartridges check they have certificates showing they meet specifications. Flow rate. Difference between the pressure before the filter and after the filter. (Sudden changes in flow or the pressure difference may indicate filter or pre-filter failure.) Performance certificates. Pressure difference is lower than usual, or flow is higher than usual. Cloudiness in the water following filtration. Customer complaints. Cases of diarrhoea in people drinking the water. Records not kept. Wash the filter cartridge and flush to waste until checks show that particle removal is again effective. Get another batch of cartridges. Consider changing filter supplier. C1.5.5 Contamination of filter housing when changing the cartridge. Disinfect filter housing when installing the cartridge, and flush to waste to remove residual disinfectant. Make sure the person replacing the cartridges knows the correct way to do it to avoid contamination. Test the water leaving the filter for the disinfectant.6 Disinfectant concentration not reduced to an acceptable level. Customer complaints. Cases of diarrhoea in people drinking the water. Continue flushing until the disinfectant cannot be detected. Train staff if necessary. C1.5.6 Flow too high for cartridge design. Keep flow rate less than the maximum the filter can handle. Flow rate. Flow too high. Cloudiness in the water following filtration. Customer complaints. Cases of diarrhoea in people drinking the water. Reduce flow to within specifications. 6 If household bleach (chlorine) is used to disinfect the filter housing, chlorine test tablets from a swimming pool test kit can be used for this. They turn pink when there is chlorine in the water. Use 1 tablet in 10ml of water; a slight pink colour indicates that the chlorine concentration is acceptable.
example-small-rainwater-supply-feb14-v2.docx