F Formation water is a waste from the processing of the oil and gas industry,if it is discharged into densely populated settlements without carrying out theprocessing process, the waste will later be dangerous and have an impact on theenvironmental ecosystem. In the Regulation of the Minister of the Environment No.19 of 2020 concerning water quality standards to match the characteristicsspecified in the regulation, therefore it is necessary to do an adsorption method forthe management of the formation water, the use of this adsorption will later changethe dissolved characteristics contained in the water. such formations such as TDS,Salinity and pH.The purpose of this research is to see whether the use of adsorption canchange the quality of formation water which was initially not in accordance withthe water quality standards to be in accordance with the Regulation of the Ministerof the Environment No. 19 of 2020. The use of this adsorption method uses materialsthat are easy to find, harmless and does not produce residues in the form of gas,namely bagasse, bamboo charcoal and bentonite, bagasse was chosen by the authoras one of the materials because it has cellulose and lignin which are carbon sourcesso that it plays an important role in the adsorption process, the use of bentonite asan adsorbent because it contains montmorillonite and colloidal particles that smallsize and large ion exchange properties and easy to absorb so that it is possible asan adsorbent, and the use of bamboo charcoal is used because it has a surface areaof 80.18 m2/g, a water content of 70% and an ash content of 5.65% so that it canbe used as an adsorbent.This research was conducted using the Freundlich and Langmuirisothermal adsorption method to test the best adsorbent in adsorption to formationwater, starting with the preparation of materials, namely formation water measuredfirst to find out what the initial formation water value was before adding theadsorbent, then the stage of making the adsorbent with an oven and activation usingchemical activation, then mixed with the activated adsorbent with formation water,then filtered the results of the adsorbent mixture with formation water, andrecalculated the TDS, Salinity and pH values of the formation water, after recalculation then calibrate by mixing the adsorbent with methylene solution blueusing a UV-VIS Spectrophotometer and the values of Co,Ce,Ct and Qe are obtainedto later calculate adsorption using the isothermal adsorption method, after carryingout this method the linear regression value is obtained to determine which is thebest adsorbent and in the adsorption of formation water.The result of this research is that the best adsorbent is obtained in theadsorption of formation water by looking at the changes in the value of TDS,Salinity and pH and using two methods of Langmuir isothermal adsorption andFreundlich isothermal adsorption using correlation coefficient values. Results Thereduction of substances contained in formation water and the use of two models ofFreundlich isothermal adsorption and Langmuir isothermal adsorption, the mostoptimum being bentonite, then bagasse and finally bamboo charcoal.