It's *almost* not worth it. More than once, when the iron starts spitting out precipitate, we've thrown it away and bought a new one. I've cleaned them too, but it doesn't work 100% and pretty quickly builds up again.

We've bought new irons for as little as $12.

And you get to salvage a nice heavy duty cord for another project.

Distilled water does work really well of course, if you are religious about using it... at 89 cents a gallon I can't see where it adds to the cost of anything. A gallon goes a long way, in an iron or in cleaning electronics.

De-ionized water is a very different animal.