This publication introduces the simulation procedure of solar water collector stagnation temperature. The calculations are for central solar water heating systems in multi-apartment residential buildings in Tel Aviv. The stagnation may be caused by the system's circulation pump being shut down by incorrect pump control. The stagnation temperature depends on the collector efficiency, which depends on the collector temperature. This results in circular calculations, which may be solved by computer simulation. The integration interval of the simulation is 1 minute. For the selected solar collector and the typical weather in Tel Aviv, the maximum stagnation temperature is 150°C in August. On extremely hot days the calculated stagnation temperature may reach 209°C. Solar water collector reaches 50°C stagnation temperature in 2.7 hours after sunrise, and 60°C in 3.1 hours, on average.