SWIM wonders how important is it to use distilled water when doing a basic ron69 extract, basing with sodium carbonate etc? SWIM would prefer to just use tap water, would this make any real difference? Thanks

Tap water should be fine.

You might procure additional contaminates from the tap water, but as SWIM can be the judge, SWIMS tap water is safe to drink (hopefully), so SWIMS spice should be safe to drink too.

It isn't very difficult to setup a home distillation apparatus which can be used to make your own distilled water and remove all the minerals and such from it.

This is just another one of those what SWIM put into it is what SWIM get out of it things. Quality products in, quality products out.

Best of luck in your quest for enlightenment!