I am not too certain about the difference in the home-vs-pet store RO filters. I do know that DI water is extremely clean. A DI filter will take out all the free ionic elements in the water. DI water shouldn't be consumed, it will run through you a sive and strip out a lot of the ions you nervous system needs to operate properly. DI water will dissolve anything you put into it more quickly and efficiently (oxygen, sea salt mixes, etc.).