Increasing water flow from taps?

I live in a rented flat. The cold water for the kitchen sink is provided from outside. This runs very fast! But the water that comes from the tank/boiler (on the same level as the flat - we have it in a small airing cupboard space) runs very slowly. So slowy and without enough pressure that i cannot stand up and take a shower as the water just won't go up that high! The shower hose will only work up to 3 feet in the air. The same goes for the hot water in the kitchen. Its very hard to get washing up liquid bubbles etc!
The boiler does not provide central heating as there isn't any - all the hot water is done by an immersion heater. Theres no problem with the water temprerature though. Its only the internal pressure thats a problem.
As i mentioned my flat is rented and the landlord said that he had the same problem when he lived there and he thinks it's from when the flats were built. But being rented theres not necessarily a lot that we can do. But is there anything we can to improve the situation???