I used to use acid in my tap water for sparge water to get the pH down to 6. I have since gone to 90% distilled and 10% tap with no acid for sparging and the final runnings pH is always well under 5.8 as long as my mash pH was good. At first I used an eye-dropper (from Walgreens) to add the acid and then went with a burette for more accuracy.
FYI, 17 drops from a Walgreens eye dropper is about 1 mL, measured with the burette.
Fermenting: Azacca Oat Pilsner, Egregious-ish, Barrel Fermented Dreg DelcoLambic, Sacch Trois Helles
Drinking: RIS v7, Doppelbock, RIS v6, Carrot Blossom Cedar Mead, Sauerkraut Fermented Gose, Gueuze, Brett Blonde, Kriek, Saison, Sour Blonde
Barrel aged: Rye Barleywine, Tripel, Wee-Heavy