Pekanbaru city development in various sectors is growing rapidly in line with the population growth. The average annual population growth rate (2017-2020) is 2,64%. The consumption of clean water for each person is influenced by various factors such as: climate, population characteristics, socio-economy, and variety of activities. The volume of grey water (non-toilet liquid waste) generated ranges from 50% -80% of the total clean water used. The characteristics of grey water depend on the diversity of household uses of clean water. This study aims to assess the generation and characteristics of grey water in the city of Pekanbaru. Furthermore, it can be seen that critical flows that have the potential to be reused, such as for watering plants and rinsing / flushing toilets, will reduce the use of clean water sources. The method used is data collection (secondary and primary) and literature studies, assessing the characteristics of grey water by referring to the quality standards of domestic wastewater PERMEN LHK RI No. 68/2016, and conducted a system assessment using MFA-STAN. The grey water survey and sampling were carried out in six densely populated sub-districts (Tampan, Tenayan Raya, Marpoyan Damai, Bukitraya, Rumbai Pesisir, and Limapuluh). The results obtained, the generation of grey water in Pekanbaru city is 57,869,008.51 m3 / year. The characteristics of the grey water in Pekanbaru City (average value) are pH 7.42; BOD 44,21 mg / L; COD 118.99 mg / L; TSS 17 mg / L; Oil and Fat 6.67 mg / L; and Ammonia 6.09 mg / L. Grey water has the potential to be reused for sanitation sector and agricultural sector so that it can reduce the use of clean water by up to 50%.