Don't forget that a properly balanced diet will provide adequate electrolytes.  All the same, I usually add something to my water just to be sure.

I am currently using various Nuun tablets.  Looking at a label, they state15 calories and one gram of added sugar and of course all the good stuff - calcium, magnesium, etc.

I started using electrolyte supplements when doing marathons and other long runs.  I found that Gatorade did not sit well when running hard, although I can tolerate it when at a hiking pace.  Diluted 50% with water, it did much better