Which pressure pump is suitable for bathroom shower?

Need to buy pressure pump for bathroom shower

Hi, I reside in a single story building with over head tank on top and have three bathrooms including one rain shower. The pressure of all showers is very low, so kindly suggest good pressure pumps between the range of 10000 to 15000 rupees as per above requirements. Kindly note, we our a family of only four members and bathroom will be used once or twice in  day.