What is the pineal gland and what does it do? i've been hearing that tap water damages it as well as a few other things with chemicals?

See answer : The pineal gland is a small (5-8 mm), pine cone shaped gland located near center of the brain. Its primary function is the secretion of the hormone melatonin which helps regulate our sleep-wake cycle and circadian rhythms and is also a powerful antioxidant. The pineal gland tends to calcify as we age with deposits of calcium, phosphorus, and fluoride. Regarding harmful chemicals: largely anecdotal.