Can n fowleri be found in city tap water? would bathing/showering be a risk if some water got in the nose?

No, but...: Many things are possible in life. The chances of catching brain-eating amoeba from tap water in the U.S. is so unlikely that the answer is "no". If the water's chlorination or disinfection became inadequate, it's possible that Naegleria could survive in that water. The level of chlorination needs to remain high enough all the way to one's tap, as Naegleria cysts are somewhat resistant to chlorine.

N. fowleri is killed: by chlorine. When municipal water supplies treat adequately - it will not contain N. fowleri. Now with that being said- "Naegleria fowleri can grow in public and private water tanks and pipes, especially where little or no disinfectant (like chlorine or chloramine) is present. It can also grow in the pipes and water heaters of homes and buildings." This is per the CDC. >>