I'm reminded of a funny episode of the Simpsons called I'm Going To PraiseLand. In it, Flanders builds a Christian themepark dedicated to his dead wife. In the park, people are amazed at a statue of his dead wife, which causes people to collapse in front of it and have visions.
Eventually, it is revealed there is a natural gas leak around the statue that causes the effects.
Zam Zam WaterZam Zam water is water from the holy city of Mecca in Islam. It is often attributed with healing properties. Studies of Zam Zam water have detected numerous minerals and compounds that might cause impacts. Most likely no different from other sources of water.
Below are a few links to pretty reputable sources that attempted to analyze the Zam Zam water.
One from the BBC and the UK Food Standard Agency. The other from the University of Heidelberg. I'd consider the University of Heidelberg study to be much more scientific as it uses multiple sources. However the BBC article is probably more popular.
They detected high levels of Arsenic, Nitrates, and Lithium along with numerous other minerals.
In the case of Arsenic and Nitrates, they exceed the World Health Organization limits by more than 3 fold.
Both Arsenic and Lithium can have medicinal properties
It is thus perhaps no coincidence that some people might attribute some healing to the water.
Of course, these are dangerous compounds and high levels or long term consumption can have dangerous health affects.
What To Do
It is of course a question of what the Saudis will do. Will they clean the water thoroughly removing such minerals, making it no different than ordinary tap water. Or do/have they left these in for the effects it can have on people?