Quality of tap water is variable in Russia. In the big cities of European Russia, the water is clean of biological contaminants, but often suffers from the presence of heavy metals, due to outdated city plumbing. In short, you'd better avoid drinking tap water. Buying bottled water is commonly practical for health. You can find it at a supermarket that costs only about 20-30 rubles for 2 liters, but watch out for scam bottled tap water.


Those are found in train stations or large shopping centers. You may be required a small fee for their use, so you'd better keep some coins and travel-sized rolls as public toilets are lack of it. The fee is usually prominantly displayed.
Don't get you trapped in Russia's Dreaded Squat Toilets. You would get out as soon as you see its horrible sight of a hole in the ground! Look for more clean toilets nearby.