Dear Shukor,

The results you have here is very interesting. However the permissible level of fluoride in drinking water is 1.5mg/L (WHO 2011). This value may be different for different climatic regions and the amount of water consumption. However, I don’t understand why permissible limit mentioned here is 0.4-0.6mg/l.

Fluoride has mostly geogenic origin, provided few anthropogenic sources are also documented in the literature. I need few details as listed below,

1. How much is the concentration of F in the groundwater

2. Please provide the details of other water quality parameters such as TDS, Ca, Mg, Na, K, So4, and Alkalinity. And also the temperature of water during treatment and before.

3. Chemicals used in the water treatment in the plant

If you provide these details, we may be able to sort this problem out.

Thanks,

Sajil

Mr. Shukor:

One factor to possibly investigate is the measurement method and its interferences. Comparison of results from colorimetric measurements is useful, but if it's possible to obtain results from ion-selective electrode or other similar methods you might be able to make better comparisons.

That said, one source of variable fluoride concentrations may be the biofilm and incorporated mineral deposition on the watermain pipe walls. Phosphates should be considered, as should calcium-fluoride deposits which may slough off pipe walls during flow changes (such as those that occur during tap opening for sample collection).

Another thought is to ensure all analyses are performed on stable samples at standard temperature.

Best regards,

David

Fluoride can enter public water systems from natural sources, including runoff from the weathering of fluoride-containing rocks and soils and leaching from soil into groundwater. Fluoride pollution from various industrial emissions can also contaminate water supplies.In his 1975 review of the environmental impact of fluoride Groth explained that most of the fluoridated water used in urban areas is returned through sewage systems to the aquatic environment. Groth described a number of studies that related environmental fluoride concentrations to specific sources. One such study measured tributaries of the East Gallatin River above the town of Bozeman, Montana, as containing 0.1 ppm (parts per million) fluoride or less, while the river below the city’s sewage outfall (the only fluoride source in the area) was found to have concentrations of 0.3 to 0.8 ppm. This clearly illustrates that fluoride added to municipal water supplies finds its way to our rivers through our sewage systems and raises background levels of the chemical.

Groth also mentions a study of fluoride input to Narragansett Bay, in Rhode Island, which showed that “36 percent of the fluoride entering the bay was due to fluoridation of water supplies in five communities on rivers feeding into the estuary. In midsummer, pollution from these sources was enough to double the fluoride content of the rivers.”

.http://www.dcbureau.org/20100706979/bulldog-blog/fluoride-from-municipal-water-supplies-is-toxic-to-fish.html

There are many factors that could contribute to fluoride pollution in drinking water which are discussed in my paper:

https://www.researchgate.net/publication/236859634_Fluoride_in_Quaternary_groundwater_aquifer_Nile_Valley_Luxor_Egypt

Article Fluoride in Quaternary groundwater aquifer, Nile Valley, Luxor, Egypt

There may be a chances of fluoride contamination by pipeline become older and corroded too that me be chances of it.

Thanks all for the explanation... really appreciate it. And to Mr PJ. Sajil Kumar. First of all as for your info although WHO set the level limit of fluoride is 1.5mg/l. Here in Malaysia we applied our own standard for fluoride as suggested by Oral Helath Division, Ministry of Health Malaysia. The value 0.4-0.6mg/l was set to prevent excess daily fluoride intake especially for child since here we're promoting them to use fluoride toothpaste. The standard value now still under review for changes.

And regarding your request, here are data that you have been requested.

1. Concentration of F in the groundwater.

Actually plant that supply water for this seven point have 2 sources. River water (Fluoride level 0.09mg/l) and groundwater itself (0.19mg/l)

2. For TDS and alkalinity we can't provide the result since our equipment have some problem during the sampling.

For raw water before treatment:

River water

Ca: 18mg/l, Mg: 1.15mg/l, Na: 3mg/l, K: Not tested , So4: 4mg/l

Ground water

Ca: 18mg/l, Mg: 2.37mg/l, Na: 4mg/l, K: Not tested , So4: 4mg/l

Water quality after treatment:

Ca: 22mg/l, Mg: 1.29mg/l, Na: 3mg/l, K: Not tested , So4: 4mg/l

3. Chemicals used in the water treatment in the plant: PAC Type III, Sodium silicofluoride, and chlorine gas

Thanks... :)

I think the source of elevated levels of flouride in the distribution system is due to the chemical used in the treatment. I suggest measuring flouride level in the raw water feeding the plant and the plant product water. If flouride level increases then you should reconsider using pure chemical or a subsitute.

The worst contaminant is HF producing industriial plants that are not provided withsystem to remove the excess of HF. Some of them release the excess during night. A second source can be certain Phosporic Rock that are nor properly defluorinated and are used for producing phosphorus fertilizer and phosphorus supplement for the cattle

The main releases of Hydrogen fluoride occur from high temperature industrial processes. The most significant releases will occur from coal-fired power stations. Hydrogen fluoride may also be released when products containing fluorine compounds (such as plastics and rubbers, fire extinguishing agents, aerosol propellants and other chemicals) are burned. Hydrogen fluoride is also released naturally from volcanic eruptions, but the amounts emitted are small in comparison to man-made sources.

Here is a link to a comprehensive reply to Flouride levels and removal https://water.tallyfox.com/answer/fluoride-removal-water