Water safety – However tempting it may be on a hot day, try to avoid water from public water tanks and fountains (şadırvan), frequently found in the vicinity of mosques. Also, though tap water is always chlorinated, it is better to drink only bottled water. Bottled water is readily available everywhere except the most remote, uninhabited spots.
The most common volumes for bottled water are 0.5 litre and 1.5 litre. 5 lt, 8 lt, 10 lt, and gigantic 19 lt bottles (known as office jar in the West, this is the most common variety used in households, delivered to houses by the employees of specialized water selling shops, because it is far too heavy to carry) can also be found with varying degrees of possibility. General price for half-a-litre and one-and-a-half-litre bottled water is YTL 0.50 and YTL 1.25 respectively in kiosks/stalls in the central parts of the cities and towns (can be much higher in a touristy or monopolistic place such as beach, airport, café of a much-visited museum, kiosk of a roadside recreation facility), while it can be as cheap as YTL 0.15 and YTL 0.35 respectively in supermarkets during winter (when the number of bottled water sales drop) and a little higher in summer (still cheaper than kiosks, though). Water is served free of charge in intercity buses, packaged in 0.25 lt plastic cups, whenever you request from the steward. In kiosks, water is sold chilled universally, sometimes so cold that you have to wait the ice to thaw to be able to drink it. Supermarkets provide it both reasonably chilled and also at room temperature.
If you have no chance of finding bottled water –for example, in wilderness, up in the eastern highlands- always boil your water; if you have no chance of boiling the water, use chlorine tablets –which can be provided from pharmacies in big cities-, or devices like LifeStraw. Also avoid swimming in fresh water, which you are not sure about its purity, and at seawater in or near the big cities –unless a beach which is declared safe to swim exists. And lastly, be cautious about water, not paranoid.