Sprinkler systems are designed and installed to control the spread of fire. They are designed based on information including the supply water flow and pressure availability to meet the hydraulic demand of the system design. One of the challenges facing sprinkler systems currently designed and installed in New Zealand is the trend of mains town supply water pressures being reduced by water supply companies to mitigate leaks in the water supply pipe work caused by ageing infrastructure and continued urban expansion; the main reason being ageing infrastructure. This presents the results from analysis related to the effectiveness of sprinklers on activation in a fire scenario and results from computer modelling of a sprinkler system to determine what the impact of reducing the pressure in a sprinkler system below the original design parameters is.