<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">The present study was carried out to assess the water quality of three lakes of Hyderabad, Telangana State, India viz., Hussain Sagar, Fox Sagar and Kattamysamma Lake by using water quality index (WQI). For this study systematic sampling has been carried out by collecting sixteen samples from each lake. The collected samples were analyzed for physico-chemical parameters like pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Hardness (TH), Total Alkalinity (TA), Sodium (Na⁺), Potassium (K⁺), Calcium (Ca²⁺), Magnesium (Mg²⁺), Nitrates (NO₃^2-), Sulphates (SO₄^2-), Fluoride (F^-) and Chloride (Cl^-) according to Standard Methods for the Examination of Water and Wastewater (APHA 2005) and Central Pollution Control Board (CPCB) guide manual: Water and Waste water analysis. The results were compared with water quality guidelines for drinking purpose (BIS 2012). The mean values of most water quality parameters were significantly higher than the accept limits in all three lakes.</span></span></p> <p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Ten important water variables were chosen to calculate Water Quality Index (WQI). All the three lakes fall under unsuitable for drinking purpose (&gt;100) according to WQI scale.</span></span></p>