Index: firmware/App/Modes/ModeHeatDisinfect.c
===================================================================
diff -u -r05019ca03114d75099dd3ae6e09f776bd8a2c46e -r9490539a39d2bfd8d40558f3c05b09b48f041e6c
--- firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision 05019ca03114d75099dd3ae6e09f776bd8a2c46e)
+++ firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision 9490539a39d2bfd8d40558f3c05b09b48f041e6c)
@@ -162,6 +162,7 @@
 static U32 ROFCoolingTimer = 0;                                                                                ///< RO filter cooling timer.
 static BOOL hasROFCirculationBeenStarted = FALSE;                                                              ///< Flag to indicate the water in RO filter has been recirculated.
 static U32 targetDisinfectTime = 0;                                                                            ///< Target disinfect time.
+static BOOL haveDrainParamsBeenInit;                                                                           ///< Boolean flag to indicate whether the drain parameters have been reset or not.
 
 // ********** private function prototypes **********
 
@@ -207,6 +208,7 @@
  * isPartialDisinfectInProgress, isDrainPumpOnInMixDrain,
  * hasROFCirculationBeenStarted, ROFCirculationTimer, targetDisinfectTime
  * ROFCirculationCoolingCounter, concentratePumpsPrimeTimer,
+ * haveDrainParamsBeenInit
  * @return none
  *************************************************************************/
 void initHeatDisinfectMode( void )
@@ -232,6 +234,7 @@
     hasROFCirculationBeenStarted = FALSE;
     concentratePumpsPrimeTimer   = 0;
     targetDisinfectTime          = 0;
+    haveDrainParamsBeenInit      = FALSE;
 }
 
 /*********************************************************************//**
@@ -1852,20 +1855,29 @@
 {
     DG_RESERVOIR_STATUS_T status = DG_RESERVOIR_ABOVE_TARGET;
 
+    // If the drain parameters of the reservoir is not initialized, initialize them
+    if ( FALSE == haveDrainParamsBeenInit )
+    {
+        initDrainParameters( r );
+        haveDrainParamsBeenInit = TRUE;
+    }
+
     BOOL isDrainComplete = hasTargetDrainVolumeBeenReached( r, drainSteadyStateTimeout );
 
     if ( TRUE == isDrainComplete )
     {
         // Set the state timer in case it needs to be used for another timeout check
-        stateTimer = getMSTimerCount();
-        status = DG_RESERVOIR_REACHED_TARGET;
+        stateTimer              = getMSTimerCount();
+        haveDrainParamsBeenInit = FALSE;
+        status                  = DG_RESERVOIR_REACHED_TARGET;
     }
     else if ( TRUE == didTimeout( stateTimer, timeout ) )
     {
         // Failed to drain on time. Update the previous heat disinfect state and transition to basic cancellation
-        prevHeatDisinfectState = heatDisinfectState;
+        prevHeatDisinfectState      = heatDisinfectState;
         alarmDetectedPendingTrigger = ALARM_ID_DG_RESERVOIR_DRAIN_TIMEOUT;
-        status = DG_RESERVOIR_NOT_REACHED_TARGET;
+        haveDrainParamsBeenInit     = FALSE;
+        status                      = DG_RESERVOIR_NOT_REACHED_TARGET;
     }
 
     return status;