Is Turkish Tap Water Safe to Drink?
The short answer: it is technically treated and safe in most cities, but it is not recommended for tourists. The chlorination and treatment meets standards, but aging pipe infrastructure can affect water quality between the treatment plant and your tap.
What Locals Do
Most Turkish people do not drink tap water at home. They buy large 19-liter water jugs (damacana) delivered to their homes or use filtered water. Bottled water is extremely cheap — about 5–10 TL for 1.5 liters from any market.
Practical Advice for Tourists
Drink bottled water (widely available everywhere). Tap water is fine for brushing teeth and cooking. Ice in restaurants is made from purified water and is safe. Salads washed with tap water are generally safe in established restaurants.
What about water in restaurants?
Restaurants serve sealed bottled water. If you are offered "su" (water), it will be bottled. Turkish çay (tea) and kahve (coffee) are made with boiled water and are perfectly safe.