Pesticides, fertilizers and industrial pollution enter our water as it cycles through the environment. As water moves through the atmosphere and ground, it acts like a large sponge and picks up mineral, chemical and gaseous pollutants.
To find water that has not been affected by pollution finds us drilling deeper and deeper wells. This water has been under ground a long time and contains heavy mineral contents. These minerals are not in balance with those found in the human blood stream, and can cause or aggravate health problems such as bladder stones, arthritis and hardening of the arteries to mention a few.
Any quality water distiller will remove most solids, salts, nitrates, bacteria and even heavy metals. Most water distillers on the market today require activated carbon filtration to remove organic chemicals, but some of the filters deteriorate with use, "dumping" stored chemicals into the purified water if not regularly replaced.
In addition, some contaminants boil at a lower temperature than water. These may rise and condense with the steam, tainting the purified water. Holes in the condensing coil don't do much but waste steam. Any stainless steel distiller has a strong likelihood of actually adding metallic contaminants; some other distillers add plastic residues.