Index: firmware/App/Modes/ModeChemicalDisinfect.c
===================================================================
diff -u -r379f78f1fad668d741b3ccf1e78c69f3fccc45b5 -r654c5598765bb862c00a0175bdac95604c6c9b24
--- firmware/App/Modes/ModeChemicalDisinfect.c	(.../ModeChemicalDisinfect.c)	(revision 379f78f1fad668d741b3ccf1e78c69f3fccc45b5)
+++ firmware/App/Modes/ModeChemicalDisinfect.c	(.../ModeChemicalDisinfect.c)	(revision 654c5598765bb862c00a0175bdac95604c6c9b24)
@@ -1382,7 +1382,20 @@
     return state;
 }
 
-
+/*********************************************************************//**
+ * @brief
+ * The handleChemicalDisinfectRinseR2ToR1AndDrainR1State function handles
+ * the chemical disinfect rinse R2 to R1 and drain R1 state. The state
+ * rinses reservoir 2 and drains reservoir 1 at the same time. If the drain
+ * process times out, it transitions to basic cancellation state, and
+ * if the rinse times out, it transitions to water cancellation state.
+ * If the drain and rinse are completed within the define time, it
+ * transitions to the next state.
+ * @details Inputs: rsrvr1Status, rsrvr2Status
+ * @details Outputs: stateTimer, rsrvr1Status, rsrvr2Status,
+ * prevChemDisinfectState, alarmDetectedPendingTrigger
+ * @return next state of the chemical disinfect state machine
+ *************************************************************************/
 static DG_CHEM_DISINFECT_STATE_T handleChemicalDisinfectRinseR2ToR1AndDrainR1State( void )
 {
     DG_CHEM_DISINFECT_STATE_T state = DG_CHEM_DISINFECT_STATE_RINSE_R2_TO_R1_AND_DRAIN_R1;
@@ -1455,8 +1468,6 @@
             // Turn on the drain pump to drain R2
             setDrainPumpTargetRPM( DRAIN_PUMP_TARGET_RPM );
 
-            // This is the last drain of heat disinfect cycle
-            isThisLastDrain = TRUE;
             stateTimer = getMSTimerCount();
             // Set the reservoir status
             rsrvr2Status = DG_RESERVOIR_ABOVE_TARGET;
@@ -1478,7 +1489,83 @@
 }
 static DG_CHEM_DISINFECT_STATE_T handleChemicalDisinfectRinseR1ToR2AndDrainR2State( void )
 {
+    DG_CHEM_DISINFECT_STATE_T state = DG_CHEM_DISINFECT_STATE_RINSE_R1_TO_R2_AND_DRAIN_R2;
 
+    if ( DG_RESERVOIR_ABOVE_TARGET == rsrvr2Status )
+    {
+        rsrvr2Status = getRsrvrDrainStatus( DG_RESERVOIR_2, DRAIN_WEIGHT_UNCHANGE_TIMEOUT, RSRVRS_INITIAL_DRAIN_TIME_OUT_MS );
+    }
+    else if ( DG_RESERVOIR_REACHED_TARGET == rsrvr2Status )
+    {
+        // Done with draining R2
+        signalDrainPumpHardStop();
+#ifndef V_2_SYSTEM
+        setValveState( VRD2, VALVE_STATE_CLOSED );
+#endif
+    }
+    else if ( DG_RESERVOIR_NOT_REACHED_TARGET == rsrvr2Status )
+    {
+        prevChemDisinfectState = state;
+        state = DG_CHEM_DISINFECT_STATE_CANCEL_BASIC_PATH;
+    }
+
+    // First reservoir 1 must be completely full
+    if ( DG_RESERVOIR_BELOW_TARGET == rsrvr1Status )
+    {
+        rsrvr2Status = getRsrvrFillStatus( DG_RESERVOIR_1, RSRVRS_FULL_VOL_ML, RSRVRS_FILL_UP_TIMEOUT_MS );
+
+        U32 drainPumpRPM = getTargetDrainPumpRPM();
+        // Keep monitoring the status of reservoir 2 as the same time
+        F32 volume = getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_2_PRIMARY );
+        // Reservoir 1 cannot be filled before reservoir 2 is filled and is overflowing to reservoir 1. If reservoir 1 has already
+        // reached to target volume, it means reservoir 2's load cell might be reading incorrect values. This situation might continue
+        // until reservoir 1 is filled up and the tubing might expand or leak.
+        // Before checking whether reservoir 1 is filled pre-maturely, we have to make sure reservoir 1 is drained completely to make
+        // sure the extra volume that is read is not because of previous water that is being drained currently and it is above 500 mL
+        if ( ( volume > RSRVRS_PARTIAL_FILL_VOL_ML ) && ( 0 == drainPumpRPM ) )
+        {
+            prevChemDisinfectState = state;
+            alarmDetectedPendingTrigger = ALARM_ID_DG_INVALID_LOAD_CELL_VALUE;
+            state = DG_CHEM_DISINFECT_STATE_CANCEL_WATER_PATH;
+        }
+    }
+    // Once reservoir 1 is completely full, monitor reservoir 2
+    else if ( DG_RESERVOIR_REACHED_TARGET == rsrvr2Status )
+    {
+        rsrvr2Status = getRsrvrFillStatus( DG_RESERVOIR_2, RSRVRS_PARTIAL_FILL_VOL_ML, RSRVRS_500ML_FILL_UP_TIMEOUT_MS );
+
+        if ( DG_RESERVOIR_REACHED_TARGET == rsrvr2Status )
+        {
+            // Done with filling, turn off the RO pump
+            signalROPumpHardStop();
+
+#ifndef V_2_SYSTEM
+            setValveState( VRD2, VALVE_STATE_OPEN );
+#else
+            setValveState( VRD, VALVE_STATE_R2_C_TO_NO );
+#endif
+
+            // Turn on the drain pump to drain R2
+            setDrainPumpTargetRPM( DRAIN_PUMP_TARGET_RPM );
+
+            stateTimer = getMSTimerCount();
+            // Set the reservoir status
+            rsrvr2Status = DG_RESERVOIR_ABOVE_TARGET;
+            state = DG_CHEM_DISINFECT_STATE_RINSE_R1_TO_R2_AND_DRAIN_R2;
+        }
+        else if ( DG_RESERVOIR_NOT_REACHED_TARGET == rsrvr1Status )
+        {
+            prevChemDisinfectState = state;
+            state = DG_CHEM_DISINFECT_STATE_CANCEL_WATER_PATH;
+        }
+    }
+    else if ( DG_RESERVOIR_NOT_REACHED_TARGET == rsrvr2Status )
+    {
+        prevChemDisinfectState = state;
+        state = DG_CHEM_DISINFECT_STATE_CANCEL_WATER_PATH;
+    }
+
+    return state;
 }
 static DG_CHEM_DISINFECT_STATE_T handleChemicalDisinfectRinseCirculationState( void )
 {