No matter what the pressure is in the mains network, your old water supply pipe may be restricting the flow of water to your property. The maximum amount of water your supply pipe can carry will be effected by its internal diameter. This will appear to you as poor pressure, leaks from old water supply pipes or fittings will also reduce the water pressure.
The pressure of the water coming through your taps can sometimes vary and there are a number of reasons for this. Water companies aim to ensure that your water pressure is no less than a target of 1 bar at the boundary of your property. Water companies have devices monitoring pressure levels throughout there mains. Water pressure in the mains network is not always constant throughout the year, nor from hour to hour throughout the day. It changes in response to the demand for water being placed on the distribution system.
There may be some occasions when a water company cannot meet it's targets. This may be owing to high water demand during hot sunny spells when temporary loss of water pressure is unavoidable. In addition, routine maintenance and improvements to the mains network or burst mains can temporarily reduce pressure - this should disappear within a day or so unless they advise you otherwise.