Many alternative health experts say that alkaline water -- whether purchased in bottles or created from your own tap with a pricey do-it-yourself ionizing purifier -- is an extra-healthy type of water to drink, with claims that it slows the aging process, increases energy, helps people with fertility issues, regulates your body’s pH level and prevents chronic diseases like cancer. 

Many people believe that the Standard American Diet (SAD) contributes to chronic low-grade acidosis, a condition associated with health issues including hormonal problems, loss of bone and metabolic problems.

Human blood has a pH of approximately 7.4 — slightly alkaline. It's essential for our bodies to maintain our pH within a tight range. Even a small fluctuation of as little as .05 in our blood pH can have severe health risks, but the pH of the organs throughout the rest of the body can vary widely.

In your stomach, where the stomach acids digest your food, the pH is 1.5 to 3.5 (acidic). TUMS and other antacids contain alkaline ions that can cancel out acidity and neutralize stomach gastric acid. You don't want to get rid of all of your stomach acid, however, as it is essential for digestion of your food!

Alternative medicine proponents such as the Budwig Center, an alternative cancer treatment clinic based in Spain, believe that our bodies need to be strictly maintained at 7.4 pH in order to achieve and maintain optimal health and to fight cancer. "If you have ever maintained a swimming pool, you will have had to verify the pH of the water on a regular basis and have had to add different chemicals to keep it at pH neutral," it says on the Center's website. "Our bodies are in effect like a swimming pool, as we are 80% water and our pH needs to be kept at 7.4 neutral to be healthy."

The Budwig Center believes that having too much acid in your body can weaken all your systems. The thinking is that your body has to then borrow minerals from your bones, teeth and organs to neutralize excess acidity. High acid levels, or acidosis, might lead to diarrhea, osteoporosis, anxiety, rheumatoid arthritis and impaired immune function. Acidosis could also interfere with your cells' ability to heal or produce energy and also allow cancer to flourish.

In a study called "Acid pH in Tumors and Its Potential for Therapeutic Exploitation" published in August 1989 in Perspectives in Cancer Research, measurement of pH in tissue showed that the microenvironment in tumors is generally more acidic than in normal tissues.

Information from https://www.livestrong.com/article/498701-what-are-the-benefits-of-drinking-alkaline-water/