An efficient numerical method with first and second order accuracy is developed by the flux split technology to simulate the water hammer problem in single and multiple pipe networks under severe transient conditions. The finite volume formulation ensures that both schemes conserve mass and momentum and produces physically realizable shock fronts. The conception of the fictitious cell at the junction is developed. The typical water hammer problem and the experiment with friction and the comprehensive orbicular network with control valve and pressure relief valve and surge tank are implemented to test the numerical method. Strong numerical evidences show that the proposed scheme has several desirable properties, such as, accurate, efficient, robust, high shock resolution, conservative and stable for Courant number. An efficient numerical method with first and second order accuracy is developed by the flux split technology to simulate the water hammer problem in single and multiple pipe networks under severe transient conditions. The finite volume formulation ensures that both both conserve mass and momentum and may physically resizable The typical water hammer problem and the experiment with friction and the comprehensive orbicular network with control valve and pressure relief valve and surge tank are implemented to test the numerical method. Strong numerical evidences show that the proposed scheme has several desirable properties, such as, accurate, efficient, robust, high shock resolution, conservative and stable for Courant number.