Permanent Hair Removal With Home Electrolysis.Needles, Epilators, Holders.

What should I expect to see when electrolysis is done on tap water?

A salesman tried to sell us some kind of water purification stuff and did what seem to be electrolysis on our tape water. Something brownish surfaced after he did that. Is that what is expected from an electrolysis on water?
Actually, the salesman did that electrolysis thingie (or so it seems) to demonstrate that our water is dirty and have to be purified.