Reliable information 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: MAV Maximum acceptable value see Drinking-Water Standards for New Zealand:2000; – – NTU nephelometric turbidity units – Preventive measures Checking preventive measures Corrective action Causes What to check Signs that action is needed Event: NOT ENOUGH WATER IN POST-TREATMENT STORAGE TO MEET DEMAND Possible hazards: Low pressure in the water supply system may allow entry of germs and chemical determinands; hazards associated with poor hygiene. Level of risk: High D1.1.1 Provide sufficient raw Pre-treatment Raw water Plan water storage to cover storage levels. storage development Insufficient seasonal variations in levels or of new supply of source water availability, source flows sources. raw water. periods of untreatable Restrict raw water quality, low. development maximum limits on in distribution consent for abstraction area until from the source. adequate Develop auxiliary sources water that can be used when available. secondary sources cannot meet demand. Refer also to Guide P1 series. D1.1.2 Design treatment plant to Calculate meet expected demand future water Insufficient for projected life of the storage use and plan water plant. levels actions to treatment meet likely capacity, or Identify treatment stages low. demand. output that are limiting capacity limited by and undertake Identify one or more modification of these. problem treatment treatment Ensure appropriate water stages not stage and safety plans are operating. increase operational for all throughput if treatment processes to possible. avoid or limit down time. D1.1.3 Construct additional Water Need for Water use storage. consumption. water use restrictions. Inadequate restrictions. Encourage water conservation during storage periods when demand is capacity. likely to be high. storage levels low. Event: NOT ENOUGH WATER IN POST-TREATMENT STORAGE TO MEET DEMAND cont’d
Reliable information 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: MAV – Maximum acceptable value – see Drinking-Water Standards for New Zealand:2000; NTU – nephelometric turbidity units Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed Event: NOT ENOUGH WATER IN POST-TREATMENT STORAGE TO MEET DEMAND Possible hazards: Low pressure in the water supply system may allow entry of germs and chemical determinands; hazards associated with poor hygiene. Level of risk: High D1.1.1 Insufficient supply of raw water. Provide sufficient raw water storage to cover seasonal variations in source water availability, periods of untreatable raw water quality, maximum limits on consent for abstraction from the source. Develop auxiliary sources that can be used when secondary sources cannot meet demand. Refer also to Guide P1 series. Pre-treatment storage levels. Raw water storage levels or source flows low. Plan development of new sources. Restrict development in distribution area until adequate water available. D1.1.2 Insufficient water treatment capacity, or output limited by one or more treatment stages not operating. Design treatment plant to meet expected demand for projected life of the plant. Identify treatment stages that are limiting capacity and undertake modification of these. Ensure appropriate water safety plans are operational for all treatment processes to avoid or limit down time. storage levels low. Calculate future water use and plan actions to meet likely demand. Identify problem treatment stage and increase throughput if possible. D1.1.3 Inadequate storage capacity. Construct additional storage. Encourage water conservation during periods when demand is likely to be high. Water consumption. Need for water use restrictions. storage levels low. Water use restrictions. Event: NOT ENOUGH WATER IN POST-TREATMENT STORAGE TO MEET DEMAND cont’d
distribution-post-treatment-storage-feb14-v2.docx