I live in a hard water area. Until now, I've been using a standard water filter like Brita...

I was hoping for a hydrogen reactor to make the water.

Definitely for ease of use, it's gotta be store bought gallons of distilled water and premeasured mineral packets.

Get a gallon, dump in the packets, store your gallon of coffee water. One jug, no liquid minerals to be finicky with, and you're done.

Plus a gallon of distilled water, at least in my area, is about $1.50.

For me, the gallon jug lives behind my coffee equipment, it's hardly noticeable unless I need it, and mineral packets sit under my filters.

6-staged filter and reverse osmosis system with a remineralization stage as the last. This gives me treated water for cooking, espresso, drinking basically on tap. My unit installed under the sink and needed a connection to water line, drain, and a dedicated spigot, so not sure how feasable that is for an apartment.

I thought you meant with reverse electrolysis

Zero water filters are great, but when the filters go bad, they go BAD. Other filters I have, you can just kinda keep using an old filter and it’s fine, they just don’t filter as well. With zero water filters, the water starts tasting like lemony sour fish as soon as it starts testing like 10 TDS… the water from the tap reads like 330 and doesn’t taste that bad.

I just buy water and refill my five gallon jugs from one of the local water filter shops, we use it for all drinking and cooking

I just buy distilled water from the grocery store and remineralize that. They come in 4L bottles in Canada, but I’ve heard in the US they come in gallon sizes, then you just get your mineral packets, combine and mix. Really easy.

The water quality straight out the tap is so good I’ve never felt any need for warer alchemy. But I do get that some places have way too heavy water.

I also have hard water and use a Brita for my drinking water, but never considered it for my coffee. Now I'll have to give that a try. I haven't gone with the Zero water filter system because that takes pretty much everything out. I think it's important to keep the minerals in your drinking water.

I'm a huge nerd but I actually found that buying good mineral waters and such, didn't do much for me. I guess I grew up with shitty water and I need a bit of that in it.

I did find that Britta's extra strong filters were more than sufficient to deal with my otherwise hard water.

There are a ton of countertop reverse osmosis filtration units in the $100 to $300 range. Find one that has a remineralization stage and go with that. Should give you a TDS in the 50ppm range which will be fine for pour over.