On February 19, 2013 we resolved not to proceed with fluoridation of the regional water schemes, but to continue fluoridating at the Mt Kynoch water treatment plant, which commenced in March 2010. This means that only residents supplied from the Toowoomba water supply scheme will receive fluoridated water.
Who is supplied from the Toowoomba Water Supply Scheme?
The Toowoomba water supply scheme supplies drinking water to:
- Cotswold Hills
- Gowrie Junction
- Gowrie Mountain
- Hodgsonvale (when the connection to the Toowoomba Water Supply Scheme is completed)
- Meringandan East
- Meringandan West
- Toowoomba City
Where does the water come from?
The water supplied is a mixture of treated dam water from the Mt Kynoch Water Treatment Plant and bore water supplied by up to 25 bores, although not all bores will be in operation at any one time. The average composition of water supplied across the entire Toowoomba water supply scheme in 2011/12 was 68.5% dam water and 31.5% bore water. These percentages will vary from year to year depending on dam levels, the number of bores available and changes to water quality.
How does this affect the amount of fluoride in the water?
The Mount Kynoch water treatment plant is the only place where fluoride is added to Toowoomba’s water supply. Fluoride is dosed to the target concentration of 0.8 mg/L, plus or minus 0.1 mg/L, as required by the Water Fluoridation Regulation 2008. Toowoomba’s bores do not contain measureable amounts of natural fluoride, meaning that the only fluoride in the drinking water supplied to residents of the Toowoomba water supply scheme is that added at the Mt Kynoch water treatment plant. In practice, this means that the amount of fluoride in the water supplied to a particular area will be directly proportional to the percentage of dam water.
Distribution of fluoridated water in the Toowoomba Water Supply Scheme
The Toowoomba water supply scheme is very complex, which means that residents of one part of the city will receive water which is different in its proportion of dam and bore water to that received by residents in another part of the city.
The city is made up of a number of distribution zones. Over an extended period of time, each of these zones will receive a relatively consistent mixture of dam and bore water. However, not only will the mixture vary from zone to zone, it will also vary from day to day, depending on the number of bores that are in use at the time, and maintenance works that might require us to temporarily change the source of water for a particular area. It will also vary from property to property within the zone, depending on its proximity to bores, reservoirs and trunk water mains. Because of these variations, it is not possible to accurately predict the mix of surface water and bore water received by any particular property.
How much fluoride is in my water?
The actual concentration of fluoride in the drinking water at any point is directly proportional to the percentage of dam water supplied to that point. An area that receives 100% dam water will receive, on average, 100% of the regulated fluoride dose, which is 0.8 mg/L. On average, areas that receive a lower proportion of dam water will receive a proportionally lower fluoride concentration.
Queensland Department of Health dental experts have advised that while 0.8 mg/L is considered to be the optimum drinking water fluoride concentration for our region, doses of 0.4mg/L or greater will have a beneficial effect.