why then do you hear about alkaline water being good?

Alkaline water is also suggested for degenerative diseases, like cancer.

Alkaline water is water with excess Oxygen and Alkaline Minerals. It has more OH- ions then H+ ions; it is highly oxygenated water with the oxygen in the stable bias OH- form that is needed by our cells. Each of these ions is bonded with an alkaline mineral in the all important colloidal form. At pH between 9-10, ionized alkaline water will have 100's of times more excess oxygen then neutral tap water and no acid elements or toxic substances in it.

Ionized water is produced by electrolysis by a Water Ionizer. This small device first filters and purifies ordinary tap water and then passes it through an electrolysis chamber with platinum coated solid titanium plates. All alkaline elements in the water are drawn towards one plate, while all acid elements like chlorine, fluoride** and heavy metals that are not captured by the filter are drawn to the other plate to be discarded. You drink the alkaline water and can use the acid water for skin care.

Japanese scientists discovered a method that puts back into water the missing ingredients that nature provides to the best natural water like Hunza water:

Alkaline pH
Hydroxyl ions
Micro-clusters
Colloidal Minerals
Active Hydrogen

The discovery of ionized water/microwater closely replicates the living qualities of high altitude mountain spring water: Fresh, Invigorating, Life Enhancing, Free Radical Scavenging and Delicious.

Alkaline water is drinking water as it should be, and as it is in natures best waters like glacier waters. Nature separates water into acid and alkaline - high altitude spring waters tend to be alkaline (for drinking), whereas hot spring waters are acidic (for skin cleansing). Fresh evian spring water for example is alkaline and has small cluster sizes.

http://glowing-health.com/alkaline-ionized-water/fundamentals.html