What you drink from the tap is as same as what you drink from the bottles if the water is bottled in Qatar or middle east except it does not come from Europa.That is why you or others are still alive. However the inner surface condition of pipelines which carries the produced water from Ras Laffan to reservoirs and Doha is hard to predict due to temperature and contaminants impact. Be relax that produced water in Qatar is safe to consume with regards to chemical limitations. So it is a bit dilemma.