diff --git a/src/controllers/tanksController.js b/src/controllers/tanksController.js
index 237703d0..44512b8c 100644
--- a/src/controllers/tanksController.js
+++ b/src/controllers/tanksController.js
@@ -6147,9 +6147,39 @@ async function processIotData(hw_Id, data) {
       const waterLevel = parseInt(waterLevelHeight * waterCapacityPerCm, 10);
 
       console.log(`🚰 Tank [${tankhardwareId}] - Level: ${tankHeight}, Calculated Water Level: ${waterLevel}`);
+      if (tankHeight <= 0) {
+        const now = moment().tz('Asia/Kolkata');
+      
+        if (!existingTank.slave_status || existingTank.slave_status !== "not_working") {
+          if (!existingTank.slave_disconnected_time) {
+            // First time signal lost
+            const disconnectedTime = now.format('DD-MMM-YYYY - HH:mm:ss');
+            existingTank.slave_status = "signal_lost";
+            existingTank.slave_disconnected_time = disconnectedTime;
+            await existingTank.save();
+            console.log(`⚠️ Slave signal lost for tank [${tankhardwareId}] at ${disconnectedTime}`);
+          } else if (existingTank.slave_status === "signal_lost") {
+            const disconnectedMoment = moment(existingTank.slave_disconnected_time, 'DD-MMM-YYYY - HH:mm:ss');
+            const minutesDiff = now.diff(disconnectedMoment, 'minutes');
+            if (minutesDiff >= 5) {
+              existingTank.slave_status = "not_working";
+              await existingTank.save();
+              console.log(`❌ Slave marked as not_working for tank [${tankhardwareId}] after ${minutesDiff} minutes`);
+            } else {
+              console.log(`⏳ Slave still within grace period (${minutesDiff} min) for tank [${tankhardwareId}]`);
+            }
+          }
+        } else {
+          console.log(`⏩ Slave already marked as not_working for tank [${tankhardwareId}], skipping update.`);
+        }
+      }
+      
+      
 
       if (tankHeight > 0 && waterLevel >= 0) {
         existingTank.waterlevel = waterLevel;
+        existingTank.slave_status = "working";
+        existingTank.slave_disconnected_time = null;
         await existingTank.save();
 
         for (const outputConnection of existingTank.connections.outputConnections) {