Water scarcity and declining hydraulic performance of water supply pipe networks have increased the difficulty of providing

reliable water services. Greywater reuse represents a potential approach to alleviating these challenges. This study evaluates

the effects of greywater reuse on the hydraulic performance and reliability of a water supply pipe network. Three greywater

reuse scenarios are considered: no reuse, satellite reuse, and on-site reuse, each examined for two water supply configurations,

with and without roof tanks. Hydraulic performance is assessed using a case study network modelled in WaterGEMS.

The results indicate that on-site and satellite greywater reuse increase pressure head by approximately 18% and 20%, respectively,

under peak demand conditions. However, greywater reuse also leads to reduced flow velocities, with values below 0.5 m/s

in certain pipes at peak demand, increasing the potential for sediment deposition. Reliability analysis under critical pipe failure

conditions demonstrates that greywater reuse substantially improves network resilience. In addition, fourteen combined

demand reduction and greywater reuse scenarios are analysed, showing that integrated strategies can reduce overall potable

water demand by up to 42.8%.