How is the Water in Turkey?

I would not drink tap water as the pipes are old and they actually smell funky in some hotels. Bottled or mineral water (or other drinks like freshly squeezed juices on the street) are so cheap it's not worth worrying about. Some people won't even brush their teeth with faucet water but I had no issues. I had no issues with the food either, but it really depends how old/ healthy you are or how predisposed you are to having those issues when eating unfamiliar foods. Everyone can have different reactions.

Avoid ice in drinks and salads.

We did not drink the water. Nor did we brush our teeth with tap water. Use bottled water.

Avoid salads? No way! They had great salads with fresh veggies (they can be grilled if you're really worried) and mezze in Turkey.

I have not been to Turkey yet, but a friend who took Rick's tour a couple years ago got sick from brushing her teeth. This is the information sent by Rick Steves' Europe for his Best of Turkey Tour -

"We strongly advise you to use bottled water, even to brush your teeth. Bottled water is available everywhere. However, you need to be prepared for the possibility of some gastrointestinal distress, as it’s not unusual for some tour members to experience this for a day or two. Please bring your own over-the-counter remedy, or ask your doctor for prescription-strength antidiarrheal medicine."

It is always best to avoid the local water in some areas of the world, and Turkey is a country where one should use caution.
Some will come on here and say they drank from the tap, didn’t watch what they ate, and had no problem.
Also, if you shouldn’t drink the water then eating salads and fruits washed in the local water is not a good idea either. Just because coffee is hot does not mean the water got hot enough for long enough to kill any disease causing organism.
Some people are strong enough to fight off gastrointestinal issues but some aren’t. Why take a chance?
The food in Turkey is very good!

My first visit was 6 years ago, Istanbul on my own, then the RS Turkey tour. My research said the following.

Do not drink tap water. Use only bottled water and make sure the bottle is sealed when you get it. Hotels and restaurants use filtered water for preparing food, so it's okay to eat fresh fruit and vegetables at them. If they serve drinks with ice, it would be with filtered water as well. Vendor stands and kiosks can't be trusted. If you want fresh fruit, get those that you can peel.

Based on that, I used bottled water for brushing my teeth.

I just got back from Turkey and this was a concern of mine before my trip.
I used bottled water to brush my teeth. Once I forgot and did get a small amount of tap water on my toothbrush.
I did take the vaccine Vivotif before my trip. My travel companion did not take the vaccine.
I ate some street food. I ate raw vegetables and fruit that wasn't peeled.
I took many packets of an off brand of pepto bismol tablets. If I thought I was taking a chance with food, I chewed two tablets first. This helps to coat your GI tract and helps decrease the likelihood that unfamiliar bacteria will take hold in your gut.

I had no GI trouble whatsoever and I have a sensitive gut.

Also, I was told that all ice cubes are made from bottled/filtered water.

My wife and I just got back from the 13-day RS Turkey tour. Our tour guide, Mine, urged us not to drink tap water or brush our teeth with it. Some hotels and restaurants even had signs warning people not to drink the water. With that said, we found bottled water to be widely available pretty much everywhere we went including on our tour bus. The driver, Mehmet, kept both bus fridges full of cold water bottles that were available for purchase throughout the tour. So, at no time did we have any trouble finding safe water to drink, even after leaving Istanbul. Also, every hotel provided 2 complimentary water bottles per day.

As for the food, particularly salads, we had no issues whatsoever. No one on our tour got sick from the water as far as I know. Unfortunately, some of us got a case of the sniffles, but that's about it. Every restaurant we went to (as part of the group, and on our own), brought sealed water bottles. So if you ask for water, and they bring you a glass, simply ask for a bottle.

I always Google "CDC Turkey" or whatever country I am wondering about to see what they say. They are pretty conservative so if they say it's good to drink then it will be. I didn't even have to look though to know Turkey is bottled water only. In the past couple of years Hungary and Coratia moved into the "standards similar to the U.S." category (yay!).

Gastro upset is an issue but much more serious is Hep A. You might want to look into getting immunized, this is a very serious disease.

Often your local medical group will have a travel health office. On occasion they have given me guidance more lenient than the CDC. For example when I went to Hungary in 2011 the CDC still had that country on the "bottled water only" list, but the local travel health office said don't worry about it.

I would err on the side of caution and stick to bottled water, although I will have to confess that I gave up on brushing my teeth with bottled water several days into my first trip to Turkey. Of course, I also have to confess that I did get sick very briefly in Ephesus. I was miserable for a couple of hours until I threw up, and then I was totally fine, as if nothing had ever happened. I always blamed it on the muesli at breakfast, not on the water.

Bottled drinking water was provided at most restaurants.

The abundance of fresh fruits and vegetables, along with marvelous grilled fish, was one of the unexpected pleasures of the trip. I ate plenty of salad, tomatoes and/or cucumbers at most meals, and fresh squeezed pomegranate juice was a big treat at roadside stands. One of my fondest memories was munching on fresh figs at the snack bar at Topkapi Palace as I watched ships go by on the Bosporus below us.

We just got back from Turkey too. My wife and I were careful not to drink the water (btw a great excuse to have another beer) but we did get a little sick. Nothing too bad and it did not affect our trip. Mostly it happened the last day and the affects were felt on our trip back home.There were a few in the group admitting to using a little Imodium but I think only one person had to skip a visit to ruins due to a stomach bug.