My water comes from a reservoir to my house through a water meter. The reservoir is only about 60 foot above my house and the water meter is 6 foot below my house, so water comes from the reservoir to down to the meter then back up to the bungalow. At best I get 1.1bar of pressure. If I run one tap none of the other like tap works. If any body else in my close runs water my shower does not work. Can I fit a pump upstream of the water meter (betwen the house and water meter) to increase my water pressure from 1.1bar to 1.5bar.

Lets knock this down to where I don't need a calculator to answer your questiom. Let's convert to PSI. 1.1 bar= 15.95 PSI. 1.5 bar= 21.75 PSI. Both are not enough for the average house pressure of 40 to 45 PSI. For that you need 2.5 bar which would give you 40 PSI.

Can I fit a pump upstream of the water meter (betwen the house and water meter) to increase my water pressure from 1.1bar to 1.5bar.
That's the only way you're going to get that house pressure up. Here we call them booster pumps. You will need a pump, pressure tank and a check valve.
The check valve will install downstream between the reservoir/water meter and the pump. The pressure tank will install after the pump and insure a steady pressure to your house. Good luck, Tom