Amount of water you should drink per day

Sometimes, one is not sure how much water to drink in a day. In my view this is what I think should be the amount. Similar principle of everything in moderation is ok if you are otherwise well.

For a normal adult about 8 cups of water is sufficient. Each cup is 200mls, that makes 1600mls of water per day. 1.5 to 2 litres per day is adequate. If you sweat a lot or exercise or have a fever or if weather is too hot, you are having diarrhoea etc, then you need to drink more. Normal kidneys have a capacity to retain or excrete water from our system to maintain normal levels of salts in the blood (electrolytes). However, drinking too much water in some may rarely lead to 'water intoxication' as the kidneys have a limit to how much water it can tackle. If you need to drink more water, you will feel thirsty and urine will be high coloured and concentrated, even you may feel a burning sensation when passing water. On drinking water the colour of urine will return to normal. Feeling very thirsty and passing too much water may be a symptom of diabetes or high serum calcium. If serum sodium ( a salt in blood) is low, sometimes doctors restrict water intake to, say, 1 litre per day till the sodium level return to normal.
I feel, you don't need to purify the water further in the UK. You can drink tap water without any problem. Read more about healthy lifestyle at ideaas.eu.