Index: firmware/App/Modes/ModeChemicalDisinfectFlush.c
===================================================================
diff -u -r9e5ee62245eb2a73b167eabd6c274a71a76a7b0e -r46a1f88d8a17cc847d3825fb40ee76844869b930
--- firmware/App/Modes/ModeChemicalDisinfectFlush.c	(.../ModeChemicalDisinfectFlush.c)	(revision 9e5ee62245eb2a73b167eabd6c274a71a76a7b0e)
+++ firmware/App/Modes/ModeChemicalDisinfectFlush.c	(.../ModeChemicalDisinfectFlush.c)	(revision 46a1f88d8a17cc847d3825fb40ee76844869b930)
@@ -86,6 +86,8 @@
 // Sample flush R1 to R2 drain R2 defines
 #define SAMPLE_FLUSH_WAIT_TIME_MS                   ( 2.5 * SEC_PER_MIN * MS_PER_SECOND )                      ///< Time to wait for sampling flush R1 to R2 drain R2 in milliseconds.
 #define SAMPLE_FLUSH_WAIT_STATE_TIMEOUT_MS          ( 30 * SEC_PER_MIN * MS_PER_SECOND )                       ///< Time to wait for sampling flush R1 to R2 drain R2 state waiting for the user to confirm in milliseconds.
+#define SAMPLE_FLUSH_RESULT_FAIL                    0                                                          ///< Chemical disinfect flush result fail.
+#define SAMPLE_FLUSH_RESULT_PASS                    1                                                          ///< Chemical disinfect flush result pass.
 
 /// Cancellation paths
 typedef enum Cancellation_modes
@@ -102,6 +104,13 @@
     BOOL hasDisStatusBeenWrittenToNV;                                                                          ///< Boolean flag to indicate whether the disinfect status been written to NV or not.
 } DISINFECT_NV_OPS_T;
 
+/// Chem flush sample results structure
+typedef struct
+{
+    BOOL hasMessageBeenReceived;                                                                               ///< Boolean flag to indicate whether the message has been received from HD.
+    U32 chemFlushSampleResult;                                                                                 ///< Chemical disinfect flush sample results back from HD.
+} CHEM_FLUSH_SAMPLE_RESULT_T;
+
 // ********** private data **********
 
 static DG_CHEM_DISINFECT_FLUSH_STATE_T chemDisinfectFlushState;                                                ///< Currently active chemical disinfect flush state.
@@ -122,6 +131,7 @@
 static DISINFECT_NV_OPS_T disinfectNVOps;                                                                      ///< Disinfect non-volatile memory operations.
 static BOOL hasAlarmBeenTriggered;                                                                             ///< Boolean flag to indicate that an alarm has been raised.
 static BOOL haveDrainParamsBeenInit[ NUM_OF_DG_RESERVOIRS ];                                                   ///< Boolean flag to indicate whether the drain parameters have been reset or not.
+static CHEM_FLUSH_SAMPLE_RESULT_T sampleResult;                                                                ///< Chemical disinfect flush sample result.
 
 // ********** private function prototypes **********
 
@@ -154,7 +164,8 @@
  * stateTrialCounter, rsrvr1Status, rsrvr2Status, haveInletWaterChecksPassed,
  * overallChemDisinfectFlushTimer, hasAlarmBeenTriggered, haveDrainParamsBeenInit
  * cancellationMode, rsrvrFillToFullStableTimeCounter, prevChemDisinfectFlushState
- * numberOfPostDisinfectRinses, chemDisinfectFlushUIState, disinfectFlushNVOps
+ * numberOfPostDisinfectRinses, chemDisinfectFlushUIState, disinfectFlushNVOps,
+ * sampleResult
  * @return none
  *************************************************************************/
 void initChemicalDisinfectFlushMode( void )
@@ -178,6 +189,8 @@
     hasAlarmBeenTriggered                      = FALSE;
     haveDrainParamsBeenInit[ DG_RESERVOIR_1 ]  = FALSE;
     haveDrainParamsBeenInit[ DG_RESERVOIR_2 ]  = FALSE;
+    sampleResult.hasMessageBeenReceived        = FALSE;
+    sampleResult.chemFlushSampleResult         = SAMPLE_FLUSH_RESULT_FAIL;
 }
 
 /*********************************************************************//**
@@ -300,6 +313,20 @@
 
 /*********************************************************************//**
  * @brief
+ * The setChemicalDisinfectFlushSampleResult function sets the received chemical
+ * disinfect sample flush result.
+ * @details Inputs: none
+ * @details Outputs: sampleResult
+ * @return none
+ *************************************************************************/
+void setChemicalDisinfectFlushSampleResult( U32 result )
+{
+    sampleResult.hasMessageBeenReceived = TRUE;
+    sampleResult.chemFlushSampleResult  = result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The stopChemicalDisinfectFlush function stops chemical disinfect flush mode.
  * @details Inputs: none
  * @details Outputs: none
@@ -369,6 +396,15 @@
 {
     DG_CHEM_DISINFECT_FLUSH_STATE_T state = DG_CHEM_DISINFECT_FLUSH_STATE_DRAIN_R1;
 
+    if ( ( TRUE == isThisLastDrain ) && ( SAMPLE_FLUSH_RESULT_PASS == sampleResult.chemFlushSampleResult ) )
+    {
+        // Drain R1 state comes after chemical flush sample result. If this is the last drain, and the sample flush result
+        // has passed write the new chemical flush sample time to the NV memory. This is done in drain R1 so the write to NV
+        // can be attempted until the write is scheduled in the NV queue.
+        // If the sample result is failed, do not update the time so the chemical disinfect sample flush is considered failed.
+        writeDisinfectDataToNV( USAGE_INFO_CHEM_FLUSH );
+    }
+
     if ( DG_RESERVOIR_ABOVE_TARGET == rsrvr1Status )
     {
         rsrvr1Status = getRsrvrDrainStatus( DG_RESERVOIR_1, DRAIN_WEIGHT_UNCHANGE_TIMEOUT_MS, RSRVRS_INITIAL_FINAL_DRAIN_TIME_OUT_MS );
@@ -718,26 +754,30 @@
 
     if ( ( TRUE == hasAlarmBeenTriggered ) && ( FALSE == isAlarmActive( ALARM_ID_DG_CHEM_DISINFECT_FLUSH_FLUSH_SAMPLE ) ) )
     {
-        signalROPumpHardStop();
-        turnOffUVReactor( INLET_UV_REACTOR );
-        turnOffUVReactor( OUTLET_UV_REACTOR );
-        requestConcentratePumpOff( CONCENTRATEPUMPS_CP1_ACID, NO_PARK_CONC_PUMPS );
-        requestConcentratePumpOff( CONCENTRATEPUMPS_CP2_BICARB, NO_PARK_CONC_PUMPS );
-        setValveState( VPI, VALVE_STATE_CLOSED );
-        setValveState( VRF, VALVE_STATE_R2_C_TO_NO );
-        setValveState( VPD, VALVE_STATE_DRAIN_C_TO_NO );
-        setValveState( VRC, VALVE_STATE_DRAIN_C_TO_NO );
-        setValveState( VDR, VALVE_STATE_DRAIN_C_TO_NO );
-        setValveState( VRI, VALVE_STATE_R1_C_TO_NO );
-        setValveState( VPO, VALVE_STATE_FILL_C_TO_NC );
-        setValveState( VRD1, VALVE_STATE_OPEN );
-        setValveState( VRD2, VALVE_STATE_CLOSED );
+        if ( TRUE == sampleResult.hasMessageBeenReceived )
+        {
+            // The sample flush message has been received.
+            signalROPumpHardStop();
+            turnOffUVReactor( INLET_UV_REACTOR );
+            turnOffUVReactor( OUTLET_UV_REACTOR );
+            requestConcentratePumpOff( CONCENTRATEPUMPS_CP1_ACID, NO_PARK_CONC_PUMPS );
+            requestConcentratePumpOff( CONCENTRATEPUMPS_CP2_BICARB, NO_PARK_CONC_PUMPS );
+            setValveState( VPI, VALVE_STATE_CLOSED );
+            setValveState( VRF, VALVE_STATE_R2_C_TO_NO );
+            setValveState( VPD, VALVE_STATE_DRAIN_C_TO_NO );
+            setValveState( VRC, VALVE_STATE_DRAIN_C_TO_NO );
+            setValveState( VDR, VALVE_STATE_DRAIN_C_TO_NO );
+            setValveState( VRI, VALVE_STATE_R1_C_TO_NO );
+            setValveState( VPO, VALVE_STATE_FILL_C_TO_NC );
+            setValveState( VRD1, VALVE_STATE_OPEN );
+            setValveState( VRD2, VALVE_STATE_CLOSED );
 
-        isThisLastDrain       = TRUE;
-        rsrvr1Status          = DG_RESERVOIR_ABOVE_TARGET;
-        hasAlarmBeenTriggered = TRUE;
-        stateTimer            = getMSTimerCount();
-        state                 = DG_CHEM_DISINFECT_FLUSH_STATE_DRAIN_R1;
+            isThisLastDrain       = TRUE;
+            rsrvr1Status          = DG_RESERVOIR_ABOVE_TARGET;
+            hasAlarmBeenTriggered = TRUE;
+            stateTimer            = getMSTimerCount();
+            state                 = DG_CHEM_DISINFECT_FLUSH_STATE_DRAIN_R1;
+        }
     }
 
     if ( TRUE == didTimeout( stateTimer, SAMPLE_FLUSH_WAIT_STATE_TIMEOUT_MS ) )