Index: firmware/App/Controllers/LoadCell.c
===================================================================
diff -u -r22176ce95e49213c48454f34ddf5d29b8109f2cb -r965eb10d9407c25e8cf334623ad45e126cecee97
--- firmware/App/Controllers/LoadCell.c	(.../LoadCell.c)	(revision 22176ce95e49213c48454f34ddf5d29b8109f2cb)
+++ firmware/App/Controllers/LoadCell.c	(.../LoadCell.c)	(revision 965eb10d9407c25e8cf334623ad45e126cecee97)
@@ -48,9 +48,9 @@
 #define LOAD_CELL_MIN_ALLOWED_WEIGHT_BEFORE_TARE_GRAMS          1600.0F                               ///< Load cell minimum allowed weight before tare in grams.
 #define LOAD_CELL_WEIGHT_OUT_RANGE_PERSISTENT_PERIOD_MS         (5 * MS_PER_SECOND)                   ///< Load cell weight out of range persistent period in milliseconds.
 #define LOAD_CELL_PRIMARY_BACKUP_MAX_DRIFT_PERSISTENT_PERIOD_MS (5 * MS_PER_SECOND)                   ///< Load cell primary and backup maximum allowed weight drift persistent period in milliseconds.
-#define EMPTY_RESERVOIR_WEIGHT_GRAMS                            1600                                  ///< Reservoirs empty weight in grams.
-#define MAX_ALLOWED_EXTRA_WEIGHT_BEFORE_FIRST_TARE_GRAMS        300                                   ///< Max allowed extra weight before first tare in grams.
-#define MAX_ALLOWED_EXTRA_WEIGHT_BEFORE_TARE_GRAMS              60                                    ///< Max allowed extra weight before tare in grams.
+#define EMPTY_RESERVOIR_WEIGHT_GRAMS                            1600.0F                               ///< Reservoirs empty weight in grams.
+#define MAX_ALLOWED_EXTRA_WEIGHT_BEFORE_FIRST_TARE_GRAMS        300.0F                                ///< Max allowed extra weight before first tare in grams.
+#define MAX_ALLOWED_EXTRA_WEIGHT_BEFORE_TARE_GRAMS              60.0F                                 ///< Max allowed extra weight before tare in grams.
 #define LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS        60.0F                                 ///< Load cell primary and backup maximum allowed weight drift in grams.
 #define DATA_PUBLISH_COUNTER_START_COUNT                        0                                     ///< Data publish counter start count.
 
@@ -82,6 +82,7 @@
 static U32 smallReadingsIdx;                                                                          ///< Index for next sample in load cell small rolling average sample array.
 static U32 largeReadingsIdx;                                                                          ///< Index for next sample in load cell large rolling average sample array.
 static DG_LOAD_CELLS_CAL_RECORD_T loadCellsCalRecord;                                                 ///< Load cells calibration record.
+static BOOL hasLoadCellBeenTared[ NUM_OF_DG_RESERVOIRS ];                                             ///< Flags indicating whether loadcells have been tared yet.
 
 // ********** private function prototypes **********
 
@@ -105,10 +106,12 @@
     loadCellDataPublicationTimerCounter = DATA_PUBLISH_COUNTER_START_COUNT;
     loadCellFilterTimerCount            = 0;
 
+    // Initialize load cell filter data and set calibration data as benign until loaded from non-volatile memory
     for ( i = 0; i < NUM_OF_LOAD_CELLS; i++ )
     {
         benignPolynomialCalRecord( &loadCellsCalRecord.loadCells[ i ] );
 
+        hasLoadCellBeenTared[ i ] = FALSE;
         loadcells[ i ].rawReading          = 0;
         loadcells[ i ].weight.data         = 0.0;
         loadcells[ i ].weight.ovData       = 0.0;
@@ -303,7 +306,7 @@
     F32 weight = getLoadCellSmallFilteredWeight( loadCellID );
 
     // Check if the load cell is being tared for the first time
-    if ( fabs( loadcells[ loadCellID ].autoCalOffset ) < NEARLY_ZERO )
+    if ( hasLoadCellBeenTared[ loadCellID ] != TRUE )
     {
         // For the first tare, the weight of the reservoir should be considered
         // The current weight of the load cell should not be greater than the weight of the reservoir + the extra weight
@@ -319,6 +322,7 @@
     {
         // Add old auto calibration offset to get back to actual weight value
         loadcells[ loadCellID ].autoCalOffset = ( loadcells[ loadCellID ].smallFilteredWeight + loadcells[ loadCellID ].autoCalOffset );
+        hasLoadCellBeenTared[ loadCellID ] = TRUE;
     }
     else
     {
Index: firmware/App/Services/Reservoirs.c
===================================================================
diff -u -r22176ce95e49213c48454f34ddf5d29b8109f2cb -r965eb10d9407c25e8cf334623ad45e126cecee97
--- firmware/App/Services/Reservoirs.c	(.../Reservoirs.c)	(revision 22176ce95e49213c48454f34ddf5d29b8109f2cb)
+++ firmware/App/Services/Reservoirs.c	(.../Reservoirs.c)	(revision 965eb10d9407c25e8cf334623ad45e126cecee97)
@@ -924,4 +924,32 @@
     return result;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The testTareReservoir function tares a given reservoir.  It is assumed
+ * that the given reservoir has already been drained.
+ * @details Inputs: drainVolumeTargetMl
+ * @details Outputs: drainVolumeTargetMl
+ * @param value ID of reservoir to tare
+ * @return TRUE if tare successful, FALSE if not
+ *************************************************************************/
+BOOL testTareReservoir( U32 value )
+{
+    BOOL result = FALSE;
+
+    if ( TRUE == isTestingActivated() )
+    {
+        if ( value < NUM_OF_DG_RESERVOIRS )
+        {
+            result = TRUE;
+            tareLoadCellRequest = TRUE;
+            testSetReservoirDrainVolumeMlOverride( 0 );
+            tareLoadCellsAtEmpty( (DG_RESERVOIR_ID_T)value );
+            testResetReservoirDrainVolumeMlOverride();
+        }
+    }
+
+    return result;
+}
+
 /**@}*/
Index: firmware/App/Services/Reservoirs.h
===================================================================
diff -u -r22176ce95e49213c48454f34ddf5d29b8109f2cb -r965eb10d9407c25e8cf334623ad45e126cecee97
--- firmware/App/Services/Reservoirs.h	(.../Reservoirs.h)	(revision 22176ce95e49213c48454f34ddf5d29b8109f2cb)
+++ firmware/App/Services/Reservoirs.h	(.../Reservoirs.h)	(revision 965eb10d9407c25e8cf334623ad45e126cecee97)
@@ -124,7 +124,8 @@
 BOOL testSetReservoirFillVolumeMlOverride( U32 value );
 BOOL testResetReservoirFillVolumeMlOverride( void );
 BOOL testSetReservoirDrainVolumeMlOverride( U32 value );
-BOOL testResetReservoirDrainVolumeMlOverride( void );
+BOOL testResetReservoirDrainVolumeMlOverride( void );
+BOOL testTareReservoir( U32 value );
 
 /**@}*/
 
Index: firmware/App/Services/SystemComm.c
===================================================================
diff -u -r439e62fe1d95d3e5398bd396e0955c1ac1ba1417 -r965eb10d9407c25e8cf334623ad45e126cecee97
--- firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 439e62fe1d95d3e5398bd396e0955c1ac1ba1417)
+++ firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 965eb10d9407c25e8cf334623ad45e126cecee97)
@@ -1193,6 +1193,10 @@
                 handleTestSetOpModeRequest( message );
                 break;
 
+            case MSG_ID_DG_RESERVOIR_TARE_REQUEST:
+                handleTestTareReservoirRequest( message );
+                break;
+
             default:
                 // TODO - unrecognized message ID received - ignore
                 break;
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r439e62fe1d95d3e5398bd396e0955c1ac1ba1417 -r965eb10d9407c25e8cf334623ad45e126cecee97
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 439e62fe1d95d3e5398bd396e0955c1ac1ba1417)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 965eb10d9407c25e8cf334623ad45e126cecee97)
@@ -1361,6 +1361,31 @@
 
 /*********************************************************************//**
  * @brief
+ * The handleTestTareReservoirRequest function handles a request to tare a
+ * given reservoir's weight.
+ * @details Inputs: none
+ * @details Outputs: message handled
+ * @param message a pointer to the message to handle
+ * @return none
+ *************************************************************************/
+void handleTestTareReservoirRequest( MESSAGE_T *message )
+{
+    BOOL result = FALSE;
+
+    if ( message->hdr.payloadLen == sizeof(U32) )
+    {
+        U32 res;
+
+        memcpy( &res, message->payload, sizeof(U32) );
+        result = testTareReservoir( res );
+    }
+
+    // Respond to request
+    sendTestAckResponseMsg( (MSG_ID_T)message->hdr.msgID, result );
+}
+
+/*********************************************************************//**
+ * @brief
  * The handleSetHDOperationMode function receives the HD operation modes data
  * publish message.
  * @details Inputs: none
Index: firmware/App/Services/SystemCommMessages.h
===================================================================
diff -u -r439e62fe1d95d3e5398bd396e0955c1ac1ba1417 -r965eb10d9407c25e8cf334623ad45e126cecee97
--- firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision 439e62fe1d95d3e5398bd396e0955c1ac1ba1417)
+++ firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision 965eb10d9407c25e8cf334623ad45e126cecee97)
@@ -389,6 +389,9 @@
 // MSG_ID_DG_SET_OP_MODE_REQUEST
 void handleTestSetOpModeRequest( MESSAGE_T *message );
 
+// MSG_ID_DG_RESERVOIR_TARE_REQUEST
+void handleTestTareReservoirRequest( MESSAGE_T *message );
+
 // MSG_ID_HD_OP_MODE
 BOOL handleSetHDOperationMode( MESSAGE_T *message );