From the blog

Algarve – drinking water

Drinking water

The normal water out of the pipe is no drinking water since it contains lots of chloride. At winter times less chloride is used while some places in Portugal use less out of other reasons.  In the end however we would not recommend drinking it or using it for Tea or Coffee. You will taste the difference!

Therefore when you go shopping for groceries keep in mind to buy 5 liter canisters. It will be used up quicker as you think. There can be bought literally in all supermarkets which are between 39 to 90 cents. Some water has more value to it since its source is from the Monchique Mountains and contains more minerals then others. As for myself I by the cheaper water for Tea and coffee or to cook and the more expensive for just drinking it directly.