I heard that if we take lot of fluid intake we are actually making our kidney oveework...is.this true? how much litres of fluid should we take?

Takes a lot: Your question is fun. Healthy kidneys are capable of managing large swings in fluid intake to keep you balanced. If you eat a healthy diet, have normal kidney function, and are purposefully forcing yourself to hold urine....(drinking/peeing contest) then you can drink many liters a day if you really wanted too. 2-3liters should prevent kidney stones but not overwhelm you if your currently helathy.