Tom;

Filters come in many types. Some remove particulate matter, and others remove ions as well as particulate matter. So, in the latter case you have deionized water. Some filters remove organics from the water as well.

Today, all commercial prepackaged products contain ingredients to cope with the largest variety of water types possible and to prevent problems. Usually, you can see no difference in any of these types of water unless you are at the extreme of hardness or sediment content.

We are moderately hard here, but have high sediment so I just use a plain filter to get rid of the sediment. It seems to give me the same results as distilled or deionized water does with D-76 and Dektol, or with KRLF or TF-4.

PE