If you wants some serious levels of ions in your water drink pond water.
I’m guessing here a bit, but this marketing stragety is born out of using ion exchange units to clean the water they sell. One problem with deionizers is they tend to make water taste like crap. So water bottlers started added ions back into the water to make it taste normal. At some time they figure this was a good marketing strategy to differentailte their products.
When I was a kid, I tagged along with a neighbor friend to stay a week at his relative's farm in the countryside. We had great fun playing at a nearby pond, where frogs were jumping around. The drinking water from their kitchen tap was cloudy and discolored, but I didn't care and drank up. Then one time a tadpole spilled into my glass from the tap. "Where is the water from?". My friend said "It's pumped from the pond!". Being a kid, I said "Cool!". Yup, serious levels of ions there.