another thing that some people might take into account when considering advantages/disadvantages, is that de-ionized, distilled or any further purified water will have more ecological footprint than your tap water (energy/material costs for the purification, packaging and transport). For me the fact that its more expensive, doesnt really change anything in terms of yields or purity and has more ecological impact makes me feel its unnecessary, but I can only talk about myself, each one will have their own motives.

Yeah that is a factor i should be taking into consideration really! end of day everyone should be reducing there footprint on the world!!!!

(least i haven't went on a plane in a long time, lol)

DI or distilled water is overkill for these purposes.

i can say my opinion.

When you live in countrys like germany and stuff you can use tap water.

I make a 50:50 mix with dwater and tap water.

At most you could use DI water for washes, but even then think about how much tap water you drink. Its not so bad stuff health wise and chemically the small amount of ions it contains aren't going to effect the extraction to any real-life degree.

I always used tap water for my STB extractions.. and that worked very fine every time.. also everyone i know uses tap water..