Question:
mild acid is not bad for the body. However, mild base is very bad. Waterin the air is naturally acidic and our bodies can compensate for mildacidicity. That is why premium bottled water has calcium and magnesiumadded. It shifts the ambient calcium ions closer to saturation where salivawon't pull calcium from your teeth or cells. Mild acidity can also helpprevent kidney stones.

Answer: Ion exchange is a much simpler process. Also, electrolysing leachesmaterial from the electrodes into the water. The water is passed overpolymer beads that are charged with acid or base. When polar ions approachthe bead, either an OH or an H is exchanged rebuilding the water moleculeand taking the unwanted ion in its place in the bead. The beads hold a goodcharge and are replenished occasional. The tanks are often used in banks.The highest number of tanks that I have used together was 42 for a plant inMexico that needed ultra-pure water. However, even DI ion exchange doesn'tget it all and ion exchange is not very good for non-polar molecules.

Reverse Osmosis pushes water through a semi-permeable membrane at highpressure. It is good at taking out many pollutants and even non-polars.Carbon filters are good for rough organics and aromatics. Distillation isas good at cleaning water as its reputation and needs to be used with othersteps. Some systems use other chemicals to target virus, bacteria, or othertoxic agents. I did one anti-bio warfare/survival straw where more of thestraw was for removing our agent then the hazard. The straw has been soldin Japan for drinking from sewers after earthquakes.

I personally drink only water bottled at a facility that uses several of theprocess together and have personally inspected the facility and its testinglab. They start with tap water but their process would work with sewerwater and deliver the same quality. They pump the tap water through a bankof sand and carbon filters then through an RO filter system. After RO, theygo through a bank of 4 mixed bed DI tanks that would take out even metalslike radium, uranium or lead. After DI they go through a UV filter just incase there was any failure. Then right before they cap the bottle theyinject the air space above the water in the bottle with ozone to kill anyairborne agents the could have floated in with the pre-cleaned bottle.