1999 318i manual - a

1999 318i manual - a 2 pronged problem that may be related. A water leak has appeared from the top hose engine housing and car is using at least 1 litre a day. This leak appeared around the same time as the second problem which is no acceleration (misfire) after the car has been standing for more than a couple of hours. Acceleration appears to be okay from cold but still loses water. A local garage temporarily fixed the "lack of power" issue and also changed the water pump but the issue has re-appeared within a week. The engine does not overheat on long trips and temperature needle stays fixed on half way. Any ideas?