Costs and Benefits of Drinking -Water Filtration

Despite considerable improvements in oral health over the last decades, oral health remains a major issue in New Zealand. Dental decay accounts for approximately 1 percent of all health loss due to early death, illness or disability. This burden exists despite public provision of dental services for children and widespread use of fluoride toothpaste. In 2015 the Ministry of Health separately commissioned CH2M Beca and Sapere to examine the costs and benefits of fluoridating community drinking-water supplies in New Zealand.

The study describes how cost estimates were derived to reflect the diversity of treatment plant types and capacities, as well as how the level of existing treatment plant infrastructure impacts the costs of adding fluoridation. It examines capital cost estimates for small to medium sized treatment plant capacities, and undertakes four case studies on larger supplies. It also includes estimates of the costs required for existing fluoridation plants to achieve compliance with the Code of Practice: Fluoridation of Drinking-Water Supplies in New Zealand (Fluoridation CoP), published by Water New Zealand in 2014.

The study finds that, over a twenty year period, the discounted net saving from adding fluoride to community water supplies (supplying water to more than 500 people) would be $1.4 billion, which is nine times the estimated costs. We also conclude that fluoridating community water supplies that supply less than 500 people is unlikely to be cost-effective. Furthermore, the study concludes that between 8,800 and 13,700 quality adjusted life years would be gained.

Overall, this study shows that fluoridation is highly cost-effective. The health benefits, while on average only marginal per person, add up to a substantial reduction in New Zealand’s disease burden across all ethnic and socioeconomic groups. This study concludes that fluoridation is far more cost-effective than most other health interventions across New Zealand, and the likelihood that the benefits are distributed equitably across society provides a further reason for water fluoridation to be maintained and extended.

The paper concludes with a discussion on how the findings of the study fed into the policy-making process, which resulted in the announcement of legislative changes that will allow District Health Boards, rather than local authorities, to decide on which community water supplies should be fluoridated.