I've seen this 'ultra-pure water dissolvess stuff like acid' stuff elsewhere, but...
Even if it were true that ultra-pure water dissolves anything... Let's do a thought experiment.
We have one bottle of ultra-pure water. We have an herb, which we will lower into the water slowly.
What happens as you dissolve the first millimeter of the herb?
Well, naturally it mixes with the water, making it no longer ultra-pure...
Actually, the more you say you have to purify the water to make it ultra-pure, the less it can dissolve without losing its quality!