Citation: Ministry of Health. 2014. Water Safety Plan Guide: Treatment Processes – Fluoridation, Version 1, ref p9. Wellington: Ministry of Health. Published in January 2014 by the Ministry of Health PO Box 5013, Wellington, New Zealand ISBN: 978-0-478-42756-1 (print) ISBN: 978-0-478-42757-8 (online) Previously published in 2001 as Public Health Risk Management Plan Guide: Treatment Processes – Fluoridation, Version 1, ref p9. This publication’s title and any reference within the text to ‘public health risk management plan’ were changed in January 2014 to reflect the December 2013 legislation change of the term ‘public health risk management plan’ to ‘water safety plan’. No other changes have been made to this document. This document is available at: www.health.govt.nz This work is licensed the Creative Commons Attribution 4.0 International licence. In essence, you are free to: share ie, copy and redistribute the material in any medium or format; adapt ie, remix, transform and build upon the material. You must give appropriate credit, provide a link to the licence and indicate if changes were made.
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 Causes Preventive measures Checking preventive measures Corrective action What to Signs that action is needed Event: FLUORIDE CONCENTRATION GREATER THAN REQUIRED FOR DENTAL PROTECTION Possible hazard: Fluoride Level of risk: High P9.1.1 Fluoride dosing solution (day tank) prepared at the wrong concentration, or using the wrong fluoride chemical, or spillage of fluoride chemical into solution preparation tank. Make sure chemicals supplied are delivered to the correct bins or containers; clearly label bins; ensure that operator is on site when chemicals are delivered. Make sure dosing solution concentration is cross checked (by a second person) after preparation and before use; check purity of chemicals supplied. Fluoride Supplier’s certificate of analysis. Fluoride concentration more than 1 mg/L. Chemical bins not labelled. Checks show dosing solution concentration incorrect. Notification of spillage. Cross checks not signed off. Label chemical bins. Supplier is required to ensure that operator is present when chemicals are delivered. Instigate checks. Change supplier. Train staff in preparation of fluoride dosing solutions (including calculations). Schedule regular split samples of fluoridated finished water to be analysed by an external approved, laboratory. Identify staff training needs and provide training. Arrange for split sample analysis. P9.1.2 from day tank. Install a devise to prevent backflow into the water supply (see Guide D2.4). Absence of a backflow preventer. Install a backflow preventer. Event: FLUORIDE CONCENTRATION GREATER THAN REQUIRED FOR DENTAL PROTECTION cont’d P9.1.3 Dosing system malfunction. Routine maintenance schedule for dose controller, or flow proportional dosing system, (whichever is appropriate) and dosing pump (see Guide P10). Fluoride Maintenance log. Fluoride weight/ Identify cause of fault and rectify.
volume calculations. Fluoride concentration more than 1 mg/L. Frequent repair needed. Maintenance log not signed off. No automatic shut off in of fault. No evidence of dose cross checks having been carried out. Replacement of controller if suspect. Ensure that all metering and dosing equipment is fail-safe and shuts off automatically on fault. Perform each day of amount of fluoride dosed against the volume of water produced. Install an alarm to indicate when the fluoride concentration exceeds to the target level. Replace controller. Install equipment with required safeguards. Instigate weight/ volume cross checks. Regular manual checks on fluoride concentration in treated water, with these samples being periodically split and sent for independent analysis. Manual sampling and analysis. P9.1.4 Dose rate set incorrectly. Periodic checks on fluoride concentration an independent method of fluoride measurement. Fluoride Calibration schedule. Fluoride concentration more than 1 mg/L. Monitoring checks show deviations from expected fluoride concentration. Adjust controller set point. Event: FLUORIDE CONCENTRATION GREATER THAN REQUIRED FOR DENTAL PROTECTION cont’d P9.1.5 Controller’s fluoride sensor out of calibration or malfunctioning Regular checks on fluoride sensor calibration using independent calibration solutions. Fluoride Calibration schedule. Recalibrate fluoride sensor. Determine reason for poor calibration and rectify.
(if dose controlled by feedback from in-line probe). fluoride sensor out of calibration. Monitoring shows fluoride concentration out of control range. Train staff in fluoride sensor calibration. Regular manual checks on fluoride concentration in treated water, with these samples being periodically split and sent for independent analysis. Use more that one fluoride sensor so that any malfunction in one will become apparent from mismatch with readings from others. Identify staff training needs and provide training. Instigate monitoring. P9.1.6 Monitoring samples not or results incorrectly recorded. Provide staff training in sampling, and record keeping. Develop monitoring schedule, with checks on data entry. Fluoride Monitoring schedule. Monitoring records. Fluoride concentration more than 1 mg/L. Monitoring schedule not followed. Errors in records. Identify staff training needs and provide training. P9.1.7 Monitoring method incorrectly calibrated, performed incorrectly, or analysis reagents deteriorated. Provide staff training in sample analysis. Develop and use a quality control programme, including periodic split-sample measurement checks using an external approved laboratory. Fluoride Quality control checks. Fluoride concentration more than 1 mg/L. Duplicate checks show errors in Identify staff training needs and provide training. Instigate quality control programme. Contingency Plan If an event happens despite preventive and corrective actions you have taken, you may need to consult with the Medical Officer of Health to assess how serious a problem is. Event – Fluoride concentration is higher than maximum acceptable value