Preventive measures Checking preventive measures Corrective action Causes What to check Signs that action is needed Event: GROWTH OF GERMS IN THE FILTER Possible hazards: Germs (released from filter into treated water). Level of risk: Moderate C1.6.1 Disinfect7 the water Record filter type Customer Avoid using a before it goes used. complaints and carbon filter or Filter used through activated sickness. disinfect the water in the wrong Check carbon cartridges before it gets to situation or recommended Timetable for used to reduce the cartridge. beyond its filter lifetime and replacing filters not taste problems capacity. installation date of followed. Disinfect water (including those cartridge in use. after the filter. claiming to stop the growth of bacteria). Plan when filters have to be Regularly replace replaced, and filter cartridges note replacement (especially carbon dates. filters). Note the replacement date. UV disinfection Event: UV DOSE TOO LOW Possible hazards: Germs not killed. Level of risk: High8 C1.7.1 Regularly clean the Light intensity. Alarm triggered Clean lamp lamp sleeves and (light intensity too sleeve and sensor Too little Alarm. light sensor lens. low). lens. UV light Signs of scale on passing Regularly replace Water flow shut off. Replace lamp. the lamp sleeve through the lamp and record the and sensor lens. Water inside lamp Move sensor so water. date. sleeve (poor seal). that it measures Records of lamp Make sure the light the light intensity replacement and No maintenance sensor is on the at the wall farthest when sleeves and records. wall of the unit from the lamp, or sensor were farthest from the buy a unit with a cleaned. lamp. sensor in the right place. Lubricate the lamp seal each time the Lubricate lamp lamp is removed seal with (use water-based approved lubricant). lubricant. Install an alarm that Add chlorine to warns when the the storage tank light intensity is too until satisfactory low and shuts off water quality can the water flow. be restored, or close the supply down and arrange for another supply of water. 7 This is best done by adding chlorine to the holding tank. Use 1 teaspoon of bleach per 150L of water in the tank. This gives a chlorine concentration of about 1 mg/L. 8 The quality of the source water and how well other treatment processes before the UV unit work will affect the level of risk.
Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed Event: GROWTH OF GERMS IN THE FILTER Possible hazards: Germs (released from filter into treated water). Level of risk: Moderate C1.6.1 Filter used in the wrong situation or beyond its capacity. Disinfect7 the water before it goes through activated carbon cartridges used to reduce taste problems (including those claiming to stop the growth of bacteria). Regularly replace filter cartridges (especially carbon filters). Note the replacement date. Record filter type used. Check recommended filter lifetime and installation date of cartridge in use. Customer complaints and sickness. Timetable for replacing filters not followed. Avoid using a carbon filter or disinfect the water before it gets to the cartridge. Disinfect water after the filter. Plan when filters have to be replaced, and note replacement dates. UV disinfection Event: UV DOSE TOO LOW Possible hazards: Germs not killed. Level of risk: High8 C1.7.1 Too little UV light passing through the water. Regularly clean the lamp sleeves and light sensor lens. Regularly replace lamp and record the date. Make sure the light sensor is on the wall of the unit farthest from the lamp. Lubricate the lamp seal each time the lamp is removed (use water-based lubricant). Install an alarm that warns when the light intensity is too low and shuts off the water flow. Light intensity. Alarm. Signs of scale on the lamp sleeve and sensor lens. Records of lamp replacement and when sleeves and sensor were cleaned. Alarm triggered (light intensity too low). Water flow shut off. Water inside lamp sleeve (poor seal). No maintenance records. Clean lamp sleeve and sensor lens. Replace lamp. Move sensor so that it measures the light intensity at the wall farthest from the lamp, or buy a unit with a sensor in the right place. Lubricate lamp seal with approved lubricant. Add chlorine to the storage tank until satisfactory water quality can be restored, or close the supply down and arrange for another supply of water. 7 This is best done by adding chlorine to the holding tank. Use 1 teaspoon of bleach per 150L of water in the tank. This gives a chlorine concentration of about 1 mg/L. 8 The quality of the source water and how well other treatment processes before the UV unit work will affect the level of risk.
example-small-rainwater-supply-feb14-v2.docx