Food and water for a 6-month old baby

When is the best time to give water to a 6-month old baby? I've been using Wilkins in preparing her formula milk. Kailangan pa bang pakuluan muna ang water (Wilkins Distilled) bago ko ipainom sa anak ko? Pinapakain ko na siya ng purees once every other day and twice a day ko ginagawa (morning & evening) or minsan ayaw niya kaya once a day lang. Am I doing right? FTM here.