Method of operating a water injection system

A method of operating a water injection system of an internal combustion engine, the system comprising an injector for injecting water at least indirectly into the combustion engine and a pump for pumping water from a tank through a feed line to the injector, the method comprising the steps of:

• determining if there is a current demand for water injection;
• if there is no current demand, checking at least one predefined standby condition to determine if, starting from a current pump performance, it is possible to meet a potential future demand for water injection;
• and
• increasing the pump performance if at least one of the at least one standby condition is fulfilled,
• wherein at least one of the at least one standby condition depends on a comparison of at least two time intervals, and wherein one said standby condition depends on a comparison of a first-injection time interval (tfi), which is one of said time intervals and corresponds to a remaining time until a first water injection is potentially needed, and a minimum-pressure time interval (tmp), which is one of said time intervals and corresponds to a remaining time until a minimum pressure needed for injection can be achieved.