disinfect the water (S1.2.1.1–2). (References in parentheses are to the Risk Information Table.) Risk Information Reliable information about water quality is essential for the proper management of a water supply. Knowledgeable and skilled staff are also essential for minimising the public health risks associated with water supplies. Please read the staff training (Guide and the G1) monitoring guides (Guide While we haven’t pointed out every detail of how these G2). documents are linked with the present document, the links are many and are important. Abbreviations: DWSNZ Drinking-Water Standards for New Zealand; MAV Maximum acceptable value – – – see DWSNZ:2000; council regional/district council or unitary authority. – Preventive measures Checking preventive measures Corrective action Causes What to check Signs that action is needed Event: EXCREMENT AND CHEMICAL CONTAMINANTS CARRIED ONTO ROOF OR INTO GUTTERING Possible hazards: Germs; herbicides, pesticides, other chemical contaminants that may be airborne. Level of risk: High1 S1.2.1.1 Tree surgery. Check tree Overgrown Tree surgery. growth at least Overgrown Clean out Disinfect water annually. trees guttering. Dirty in tank or treat guttering guttering. with UV at point May cause Provide a grate at least of use. bird life, over the E. coli is annually. possums or downpipe-gutter detected in Disconnect rotting connection, or 100 ml sample. downpipe from vegetation to over the whole quality tank and clean contaminate guttering, to limit directly after guttering. the roof entry of rain. Disinfect water catchment vegetation into the in tank (1 mg/L area. tank. of chlorine for Water clean water,* dripping off possibly up to branches 5 mg/L if water onto the roof is poor quality) may carry or treat with UV at point of use. Dead animals may fall into the guttering.
disinfect the water (S1.2.1.1–2). (References in parentheses are to the Risk Information Table.) Risk Information Reliable information about water quality is essential for the proper management of a water supply. Knowledgeable and skilled staff are also essential for minimising the public health risks associated with water supplies. Please read the staff training (Guide G1) and the monitoring guides (Guide G2). While we haven’t pointed out every detail of how these documents are linked with the present document, the links are many and are important. Abbreviations: DWSNZ – Drinking-Water Standards for New Zealand; MAV – Maximum acceptable value – see DWSNZ:2000; council – regional/district council or unitary authority. Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed Event: EXCREMENT AND CHEMICAL CONTAMINANTS CARRIED ONTO ROOF OR INTO GUTTERING Possible hazards: Germs; herbicides, pesticides, other chemical contaminants that may be airborne. Level of risk: High1 S1.2.1.1 Overgrown trees May cause bird life, possums or rotting vegetation to contaminate the roof catchment area. Water dripping off branches onto the roof may carry Dead animals may fall into the guttering. Tree surgery. Clean out guttering. Provide a grate over the downpipe-gutter connection, or over the whole guttering, to limit entry of vegetation into the tank. Check tree growth at least annually. guttering at least annually. quality directly after rain. Overgrown Dirty guttering. E. coli is detected in 100 ml sample. Tree surgery. Disinfect water in tank or treat with UV at point of use. Disconnect downpipe from tank and clean guttering. Disinfect water in tank (1 mg/L of chlorine for clean water,* possibly up to 5 mg/L if water is poor quality) or treat with UV at point of use.
source-roof-catchments-feb14-v2.docx