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Dear Jan

I have just looked up the World Health Organisation guidelines for maximum levels of the two chemicals that you mention in drinking water;

• Sodium – 200mg/l (you have 488mg/l so are in excess of the guideline) • Fluoride - 1.5 mg/l (you have 15, you do nor state units but presumably mg/l and are therefore in excess of this guideline)

You will be aware of the debate over the adding of fluoride to water for dental health benefits but the levels involved are generally less than 1.0mg/l and high levels can be toxic.

High sodium levels would have implications for the risk of hypertension, diabetes and chronic kidney diseases.

Best regards

Martin