Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -r46b163d19c65e8c21db7b0247bbb1af0dba1ece5 -rab09af73712b54877a5d536426d2b4feb3af7fed
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 46b163d19c65e8c21db7b0247bbb1af0dba1ece5)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision ab09af73712b54877a5d536426d2b4feb3af7fed)
@@ -56,6 +56,7 @@
 static BOOL flushStartReqReceived;                                                             ///< Flag indicates user has requested initiation of flush mode.
 static BOOL heatDisinfectStartReqReceived;                                                     ///< Flag indicates user has requested initiation of heat disinfect mode.
 static BOOL chemDisinfectStartReqReceived;                                                     ///< Flag indicates user has requested initiation of chemical disinfect mode.
+static GENERIC_CONFIRM_ID_T  disinfectCancelReqID;                                             ///< ID of requested cancel disinfect mode.
 static DG_DISINFECT_STATE_T dgDisinfectState;                                                  ///< DG disinfect state to be boadcast to UI.
 
 static U32 dataPublishCounter = 0;                                                             ///< Disinfects data publish counter.
@@ -64,6 +65,8 @@
 
 // ********** private function prototypes **********
 
+static void handleDisinfectCancel( BOOL stop );
+
 static HD_STANDBY_STATE_T handleStandbyModeStartState( void );
 static HD_STANDBY_STATE_T handleStandbyModeWaitForTreatmentState( void );
 static HD_STANDBY_STATE_T handleStandbyModeWaitForDisinfectState( void );
@@ -99,6 +102,7 @@
     dataPublishCounter            = 0;
     heatDisinfectStartReqReceived = FALSE;
     chemDisinfectStartReqReceived = FALSE;
+    disinfectCancelReqID          = GENERIC_CONFIRM_ID_NONE;
     dgDisinfectState              = DG_DISINFECT_NOT_RUNNING_STATE;
 }
 
@@ -160,6 +164,8 @@
 {
     BOOL stop = isStopButtonPressed();
 
+    handleDisinfectCancel( stop );
+
 #ifndef RUN_WITHOUT_DG
     // State machine to get DG to prep a reservoir so we can start a treatment
     switch ( currentStandbyState )
@@ -470,6 +476,87 @@
 
 /*********************************************************************//**
  * @brief
+ * The handleDisinfectCancel function handles
+ * DG disinfect cancel UI interaction.
+ * @details Inputs: none
+ * @details Outputs: none
+ * @param stop button status
+ * @return none
+ *************************************************************************/
+static void handleDisinfectCancel( BOOL stop )
+{
+    CONFIRMATION_REQUEST_STATUS_T confirm_status;
+    GENERIC_CONFIRM_ID_T confirm_id;
+
+    if ( ( STANDBY_DG_FLUSH_IN_PROGRESS_STATE == currentStandbyState ) ||
+         ( STANDBY_DG_HEAT_DISINFECT_IN_PROGRESS_STATE == currentStandbyState ) ||
+         ( STANDBY_DG_CHEM_DISINFECT_IN_PROGRESS_STATE == currentStandbyState ) )
+    {
+        if ( ( TRUE == stop ) && ( GENERIC_CONFIRM_ID_NONE == disinfectCancelReqID ) )
+        {
+            if ( STANDBY_DG_FLUSH_IN_PROGRESS_STATE == currentStandbyState )
+            {
+                confirm_id = GENERIC_CONFIRM_ID_DISINFECT_STOP_WATERFLUSH;
+            }
+            else if ( STANDBY_DG_HEAT_DISINFECT_IN_PROGRESS_STATE == currentStandbyState )
+            {
+                confirm_id = GENERIC_CONFIRM_ID_DISINFECT_STOP_HEAT;
+            }
+            else if ( STANDBY_DG_CHEM_DISINFECT_IN_PROGRESS_STATE == currentStandbyState )
+            {
+                confirm_id = GENERIC_CONFIRM_ID_DISINFECT_STOP_CHEMICAL;
+            }
+            // Send message to UI to indicate user request to cancel disinfect
+            disinfectCancelReqID = addConfirmationRequest( confirm_id, GENERIC_CONFIRM_CMD_REQUEST_OPEN, 0 );
+        }
+        else if ( GENERIC_CONFIRM_ID_NONE != disinfectCancelReqID )
+        {
+            // Get the confirmation request.  It consumes the request if completed and responds to UI.
+            confirm_status = getConfirmationRequestStatus( disinfectCancelReqID );
+            switch ( confirm_status )
+            {
+                case CONFIRMATION_REQUEST_STATUS_ACCEPTED :
+                    // Clear request active status
+                    disinfectCancelReqID = GENERIC_CONFIRM_ID_NONE;
+
+                    switch ( currentStandbyState )
+                    {
+                        case STANDBY_DG_FLUSH_IN_PROGRESS_STATE:
+                            cmdStopDGFlush();
+                            break;
+
+                        case STANDBY_DG_HEAT_DISINFECT_IN_PROGRESS_STATE:
+                            cmdStopDGHeatDisinfect();
+                            break;
+
+                        case STANDBY_DG_CHEM_DISINFECT_IN_PROGRESS_STATE:
+                            cmdStopDGChemicalDisinfect();
+                            break;
+
+                        default:
+                            // UI Confirm already closed.  Nothing to do.
+                            break;
+                    }
+                    break;
+
+                case CONFIRMATION_REQUEST_STATUS_TIMEOUT :
+                case CONFIRMATION_REQUEST_STATUS_REJECTED :
+                    // Clear request active status
+                    disinfectCancelReqID = GENERIC_CONFIRM_ID_NONE;
+                    break;
+
+                case CONFIRMATION_REQUEST_STATUS_PENDING:
+                case CONFIRMATION_REQUEST_STATUS_UNUSED:
+                default :
+                    // Nothing to do
+                    break;
+            }
+        }
+    }
+}
+
+/*********************************************************************//**
+ * @brief
  * The handleStandbyModeStartState function handles the standby start state.
  * This state waits for the door to be closed and then initiates homing of
  * pumps and valves and transitions to the wait for treatment state.