This planning is aim to design the plumbing system at Gayanti City Apartment with a separate system or grey water recycling system so that the efficiency cost of the recycling system will be known. Clean water system from PAM JAYA DKI and recycle water system from grey water that distributed to Waste Water Treatment Plant (WWTP) to be treated and reused for flushing closet and watering plants are designed for this apartment. The amount of the clean water needed is 116.6 m3/day and the amount of the recycle water needed is 18.64 m3/day. Water supply system that applied to this apartment is roof tank system. Calculation of water consumption's fluctuations to determine the capacity of reservoirs and pumps are using Four Winds Apartment, Bellagio Apartment, Thamrin Residences Apartment, and Karet Kuningan Apartment as a comparison with the same criteria as the designed apartment. The capacity of the clean ground water tank is 123.5 m3 and the recycle ground water tank is 12 m3. Transfer pumps work for 12 hour/day (1 time pause) and the capacity of clean roof water tank is 31.5 m3 and the recycled one is 6.7 m3. Based on the chosen alternative in design, Gayanti City Apartment is using the first water supply system alternative that needs 18 stand pipes of clean water and 18 stands pipes of recycle water with 4 PRVs mounted on each stand pipes and booster pump installed for the top 6 floors. The amount of clean water needed is 116.6 m3/day and recycle water is 18.64 m3/day. Waste water produced is equal to 93.28 m3 which 80% of it is the grey water that will be treated in Waste Water Treatment Plant into recycle water. Total amount of clean and recycled water investment and reservoir constructions is Rp. 1,637,227,201,- and percentage of clean water that can be saved from the application of recycling system is 18% with total efficiency cost Rp 233,932/day or Rp 7,017,960/month.