My dear brothers, please see hadith from Bukhari and Muslim below (the two most authentic sources of hadith).

Reported by al-Bukhaari, 3/492. According to the hadeeth of Abu Dharr (may Allaah be pleased with him), the Prophet (peace and blessings of Allaah be upon him) said concerning the water of Zamzam, “It is a blessing, and it is food that satisfies.” (Reported by Muslim, 4/1922). Al-Tayaalisi (61) added, in a version that he narrated: “and a cure for the sick.” I.e., drinking the water of Zamzam means that a person does not need to eat, and it will cure his sickness – but this is when he drinks it with faith and sincerity, as proven in the hadeeth of Abu Dharr al-Ghifaari who stayed in Makkah for a month without any nourishment except Zamzam water.

My request is to exercise caution in the matters concerning religious affairs. Not only in regards with religion of Islam but any religion. When we say "people who fall for healing powers" we are essentially negating authentic hadith of our beloved prophet Muhammad (pbuh). May Allah save us from making such mistakes and accept our taubah. Jazak Allah Khair.