Query on water pressure problem

Pressure Pump information needed


I lives in a 3BHK in Bangalore on 3rd Floor(top floor) and we have an overhead tank for supply, and we have added a Kranti Water meter now.
the problem is that the pressure is very low and when water taps are opened simultaneously in other bathrom, it becomes too low. I have researched on the internet & learned that there are pressure pump available to boost water supply.

Which one should I choose ? As after the water meter installation I have 4 outlets , 3 in bathrooms and 1in the kitchen , plus I don't want to give pressure outlet to kitchen as maids can waste a lot of water.

Please suggest how I can design a solution ? There are 2 Kirloskar models,  should I go for 1 HP or 0.5 HP ? They switch on automatically when tap is opened. The links I have referred to are here:
Thanks in advance