Index: firmware/App/Modes/ModeGenIdle.c
===================================================================
diff -u -r4bd3bf3483660050d3026f7f9adff43782bfc620 -r7a58e4adbfabe04c56ddca3f5aecdac2071cd1d0
--- firmware/App/Modes/ModeGenIdle.c	(.../ModeGenIdle.c)	(revision 4bd3bf3483660050d3026f7f9adff43782bfc620)
+++ firmware/App/Modes/ModeGenIdle.c	(.../ModeGenIdle.c)	(revision 7a58e4adbfabe04c56ddca3f5aecdac2071cd1d0)
@@ -47,6 +47,7 @@
 
 #define TARGET_RO_PRESSURE_PSI                  130                                            ///< Target pressure for RO pump.
 #define TARGET_RO_FLOW_RATE_L                   0.8F                                           ///< Target flow rate for RO pump.
+#define MAX_IDLE_RSVR_WEIGHT_GAIN_ML            200.0F                                         ///< Maximum fluid gain of inactive reservoir in Gen Idle mode (mL)
 #define HD_LOST_COMM_TIMEOUT_MS                 (5 * SEC_PER_MIN * MS_PER_SECOND )             ///< The time of HD lost comm before DG transition back to standby.
 #define BAD_FILL_SUBSTATES_PUB_INTERVAL         ( MS_PER_SECOND / TASK_GENERAL_INTERVAL )      ///< Interval (ms/task time) at which the bad fill sub-states is published on the CAN bus.
 #define DATA_PUBLISH_COUNTER_START_COUNT        61                                             ///< Data publish counter start count.
@@ -66,6 +67,8 @@
 static OVERRIDE_U32_T genIdleDataPublicationInterval = { BAD_FILL_SUBSTATES_PUB_INTERVAL,
                                                          BAD_FILL_SUBSTATES_PUB_INTERVAL,
                                                          0, 0 };                               ///< Interval (in ms) at which to publish bad fill sub-states to CAN bus.
+static F32 initialReservoirWeight;                                                             ///< Initial weight of inactive reservoir in Gen Idle mode.
+static DG_RESERVOIR_ID_T inactiveReservoir;                                                    ///< Inactive reservoir
 
 // ********** private function prototypes **********
 
@@ -79,6 +82,7 @@
 static DG_GEN_IDLE_MODE_BAD_FILL_STATE_T handleSecondDrainState( void );
 static DG_GEN_IDLE_MODE_BAD_FILL_STATE_T handleRefillState( DG_GEN_IDLE_MODE_STATE_T* idleState );
 
+static void checkInvalidReservoirFill( void );
 static void publishGenIdleSubstates();
 
 /*********************************************************************//**
@@ -140,6 +144,9 @@
 
     setCPLDCleanLEDColor( CPLD_CLEAN_LED_OFF );
 
+    inactiveReservoir = getInactiveReservoir();
+    initialReservoirWeight = getReservoirWeight( inactiveReservoir );
+
     return genIdleState;
 }
 
@@ -247,6 +254,7 @@
             break;
     }
 
+    checkInvalidReservoirFill();
     publishGenIdleSubstates();
 
     return (U32)genIdleState;
@@ -467,6 +475,34 @@
 
 /*********************************************************************//**
  * @brief
+ * The checkInvalidReservoirFill function checks for reservoir filling in
+ * generation idle mode when it should be constant.
+ * @details Inputs: inactiveReservoir, initialReservoirWeight
+ * @details Outputs: inactiveReservoir, initialReservoirWeight
+ * @return the next state
+ *************************************************************************/
+static void checkInvalidReservoirFill( void )
+{
+    DG_RESERVOIR_ID_T currentInactiveReservoir = getInactiveReservoir();
+    F32 reservoirWeight = getReservoirWeight( currentInactiveReservoir );
+
+    if ( currentInactiveReservoir != inactiveReservoir )
+    {
+        // Inactive Reservoir changed, update the start value
+        inactiveReservoir = currentInactiveReservoir;
+        initialReservoirWeight = getReservoirWeight( inactiveReservoir );
+    }
+
+    // Check for unwanted filling unless a transfer is in progress
+    if ( ( FALSE == isReservoirTransferInProgress() ) && ( reservoirWeight > ( initialReservoirWeight +  MAX_IDLE_RSVR_WEIGHT_GAIN_ML ) ) )
+    {
+        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DG_INACTIVE_RESERVOIR_WEIGHT_OUT_OF_RANGE, initialReservoirWeight, reservoirWeight );
+    }
+
+}
+
+/*********************************************************************//**
+ * @brief
  * The publishGenIdleSubstates function publishes gen idle
  * sub-states at the set interval.
  * @details Inputs: handleBadFillFlag, badFillState, targetFillVolumeML,