Don’t use a Brita pitcher. Those carbon filters are designed for taste and smell, not nitrate removal. You’ll be drinking fancy-tasting poison.
Also, don’t rely on “water softening”. That system is for hardness minerals like calcium and magnesium, not nitrates. It’s like using a salad spinner to bail out a leaking boat—wrong tool, wrong job.
And for the love of all that is holy, do not drink water that smells like rotten eggs. That might be hydrogen sulfide, not nitrates, but either way: no. Just no.