ZAM ZAM is about 18*14 feet and 13 meters deep well. It started 4000 years ago.
Never dried since then never changed taste.
No Algae or Plant growth in the well.
This small well provides water to Millions of people. Through Heavy motors pulling 8000 liters per second (69.12 core liter in 24 hrs) & after 24 hours it completes its level in only 11 mints. Thus its Alter level never decreases.