HOW is it that one side of the building gets water from the overhead tank for more time than the other with all other parameters equal?

If all are equal there should be no difference. How do you know they are equal?

Sir, Thank you for the prompt answer. Out plumber says that all connections are okay. I am not an expert. Still. Can see that the level of the outlets for each side is same. But one side gets water for more time than the other side. Please give a suggesting to get rid of the imbalance VNKesavan

Sir,
I am giving more information for my question. Ours is a four story building with 22 flats ,nine on each side and four in the center. WE have one OH tank catering to our water needs. There are two outlets one of which caters to nine flats and the other 13. The levels of outlets are at the same height. There is a pipe to allow excess water to come out on the first side only. Each flat has four taps. As the water is pumped the side which caters to nine flats starts getting water and the other side starts getting supply after say 30 minutes. The first side gets an additional 30 minutes after the 13 flats stopped getting water. As an experiment, we closed both outlets till the tank is full and although every flat got water at the same time the side with nine flats got more water than the 13 flats.as above.please throw some light on the above problem as it is not always that we get a full tank. VNKesavan .

If all are equal there should be no difference. How do you know they are equal?

Dear sir, I am depending on the plumber only. I give more details now: There are 22 flats nine each on each side with 4 in the center. There are four stories and one OH tank caters to water needs. The OH tank has two outlets on each side and one caters to 9 flats and the other to 13 flats. A pipe to allow overflow when the tank is full is on the side catering to the nine flats. These nine flats get water supply even after the other side stopped getting it that too for a longer time. The outlets are at the same level . The plumber says all connections are okay. Please give some idea as to the reason for this unequal water supply.The problem is more acute when the tank is not full due to cut in supply by the municipal corporation. Thank you, VNKesavan.