Istanbul water
 

Is bottled water advised when staying in Istanbul

For drinking, yes. Water served at simple restaurants may be also from larger containers and should be fine.

The tap water is safe but heavily chlorinated and tastes awful even when used for making coffee or tea.

In rural restaurants in Turkey they may serve you water from fresh water springs. Have never heard anyone complaining about water at any location in Turkey.

Thanks.

I drank water right from the spigot in Istanbul and Buyukada and I was fine.

Thin

Most apartments in Turkey have huge containers of filtered water. They get delivered to homes when you are out. They are similar to the water found in offices in the US. No one I met advised drinking the tap water--and I didn't (unless I unknowingly drank it in a restaurant).

Even used bottled water to brush my teeth.

I did use sink water to brush my teeth, but that is about it.