H Hotel's wastewater is the potential source of environment pollution and should be handled and treated carefully to fulfill the standard, which had declared, by the government. The increasing of tourism's activity automatically increases the hotel's industries either, so that increase the potential environment pollution source which caused by the wastewater.To treat haters wastewater in order to prevent environment pollution needs the action to build and manage the infrastructure and facilitation that applied the effective technology so the result of that treatment can fulfill the environment standard. For this sake the restudy has executed to measure how further the effort to manage the wastewater by the hotel themselves and executed according to rule of standard, in this case Legian Beach Hotel WastewaterTreatment Plan (WWTP).This WWTP treats the wastewater that has been produced by kitchen unit, laundry unit and rooms unit, which has capacity 477.60 m3/day. Waste water which flow out from bungalow is treated separately in each bungalow's septic tank. The Wastewater Treatment Plan consist of some common units likes collecting tank, primary tank (2 tanks), balancing tank, DO tank, bio filter, sludge storage, effluent tank ; and generallyit is the biologicWWTP.Rate of waste water input quantity which will be treated in WWTP came from kitchen and restaurant 314.70 m3/hour; laundry 131.40 m3/hour; hotel rooms 31.50 m3/hour. From the datum, we can conclude that the large quantity of wastewater,which has treated inWWTP, has flowed out from out from the restaurantand kitchen.After evaluating, balance tank in this hotel's WWTP can also be functioned as an equalization tank, and has volume 23 m3 (larger than 20 m3/day as a standard of equalization tank). The result of wastewater parameters analyzes showed that the quality of WWTP treatments is efficient enough with the quantity of BOD, COD and DO is far below the standard line. However, the quantity of P04, turbidity and TSS is above the line. Because of this thing, the advance experiment that uses the jar test (with Alum and PAC) method has carried out. It aimed to obtain the optimal dose of coagulants and to analyze the potency of water or just for irrigation purpose.After evaluating and analyzing this WWTP. we can conclude contrast thing between some positive points and some negative points. The balancing tank is able to balance the excessive wastewater supplies. The quantity of P04 decreases after using Aluminum Sulfate and PAC. The decreasing of BOD percentage proved that the use of bio filter (plastic medium) is efficient but the bad point is no flow meter gauge and the unused returned sludge system.