Q & A: What is deionized water? | Department of Physics ...
Deionized Water (We call it "DI water" in the chemistry labs) is just what it sounds like: Water that has the ions removed. Tap water is usually full of ions from the soil (Na +, Ca 2+), from the pipes (Fe 2+, Cu 2+), and other sources.Water is usually deionized by using an ion exchange process.