We know that our body is mostly water. From birth, when we are about 80% water, to death, when we are about 60% water, it is critical that we get enough and that our water is life-giving, not harmful.
Getting enough is the first key to maintaining our body's balance and the fluid level that we need. Our bodies need about 1 ounce of pure water per pound of body weight per day. Studies have shown that keeping our body well hydrated, with a bare minimum of ¾ ounce of water per pound of body weight per day keeps our skin healthy, our bowels working well, and our systems functioning appropriately. This water must be pure. Some recommend drinking only distilled water; we have found that alkaline water is more helpful.
Of course, we all recognize the need for water to be clean and free of chemical contaminants. Those chemical contaminants include chlorine, fluoride, and many other "additives" to water. A good carbon filter will eliminate most of these.
What else makes water harmful or healthful? Having water that has an acidic pH can actually cause our body to have to work harder as it works to balance our level of alkalinity. Our blood pH must be maintained at 7.365 for survival. If we are adding acidic forming water into our body, our body systems will pull minerals from other places that are not as critical, such as nerve sheath, bones, or other tissues to keep us alive.
What waters are properly alkaline? Remember we need to keep our system at 7.365 pH, and anything less than 7.0 pH is acid, anything above 7.0 pH is alkaline. Reverse Osmosis water is 5.0, or quite acid. Most tap water is between 6.0 and 8.5, depending on your municipal system and how it is treated. Bottled waters vary widely, but anything labeled, "Filtered" is Reverse Osmosis and should be avoided as it is acid.
Other drinks that can be very harmful due to the acid-forming potential in the body are colas (pH 2.5, or 100,000 times more acidic than the blood's needed level of alkalinity), sports drinks (pH 2.5), and other sodas (pH 3.0). Freshly made vegetable juice, on the other hand, is about pH 9.0. Additionally, herbal "teas" are between 7.5 and 8.5 pH. To maintain our body's fluids at the proper levels for best functioning, make sure you are drinking water, herbal "teas", and eating fresh vegetables and fruits that are high in water.
A good research article on water is at this link, https://drlwilson.com/ARTICLES/REVERSE%20OSMOSIS.htm
Disclaimer: I am not affiliated with the Dr. Christopher Corporation. The conclusions I am sharing are from my own experience. This information is for education only and makes no claims of medical advice.