How much fluid for 6-mo old infant?

Baby has always had tendency to regurgitate surprising amount of formula after feeding, regardless of burping. Doctor suggested techniques and formula change with some success - trial and error. Adding rice cereal to baby formula thickens it and results in significantly less loss through regurgitation. My question has two points: does the addition of rice cereal reduce fluid intake and does this diminish necessary hydration? Thanks for your insight.