Index: firmware/App/Controllers/ConductivitySensors.c
===================================================================
diff -u -rc230be1bd4296324bf5dfc288c212eb7c2ce5d2d -r96dd3e3d17fdfd5b70870bfc15d12a147f4900ee
--- firmware/App/Controllers/ConductivitySensors.c	(.../ConductivitySensors.c)	(revision c230be1bd4296324bf5dfc288c212eb7c2ce5d2d)
+++ firmware/App/Controllers/ConductivitySensors.c	(.../ConductivitySensors.c)	(revision 96dd3e3d17fdfd5b70870bfc15d12a147f4900ee)
@@ -20,6 +20,7 @@
 #include "FPGA.h"
 #include "NVDataMgmt.h"
 #include "MessageSupport.h"
+#include "ModeFill.h"
 #include "OperationModes.h"
 #include "PersistentAlarm.h"
 #include "SystemCommMessages.h"
@@ -52,6 +53,9 @@
 #define MAX_COND_SENSOR_CPI_WARNING_LOW_US_PER_CM       200.0F                                      ///< Maximum allowed low conductivity value in uS/cm.
 #define MIN_COND_SENSOR_CPI_WARNING_LOW_US_PER_CM       220.0F                                      ///< Minimum allowed low conductivity value in uS/cm.
 
+#define MAX_RO_ONLY_COND_SENSOR_CPI_HIGH_US_PER_CM      100.0F                                      ///< Maximum RO only mode high conductivity value in uS/cm.
+#define MIN_RO_ONLY_COND_SENSOR_CPI_HIGH_US_PER_CM       90.0F                                      ///< Minimum RO only mode high conductivity value in uS/cm.
+
 #define MAX_ALLOWED_UNCHANGED_CONDUCTIVITY_READS        ( MS_PER_SECOND / TASK_PRIORITY_INTERVAL )  ///< New reading every 800 ms, expect to get valid new reading in 1s.
 #define MAX_CONDUCTIVITY_SENSOR_FAILURES                5                                           ///< maximum number of conductivity sensor errors within window period before alarm.
 #define MAX_CONDUCTIVITY_SENSOR_FAILURE_WINDOW_MS       ( 60 * MS_PER_SECOND )                      ///< Conductivity sensor error window.
@@ -299,9 +303,20 @@
     {
         DG_OP_MODE_T opMode   = getCurrentOperationMode();
         F32 conductivity      = getConductivityValue( CONDUCTIVITYSENSORS_CPI_SENSOR );
-        BOOL isConductTooLow  = ( conductivity < MAX_COND_SENSOR_CPI_WARNING_LOW_US_PER_CM ? TRUE : FALSE );
-        BOOL isConductTooHigh = ( conductivity > MAX_COND_SENSOR_CPI_WARNING_HIGH_US_PER_CM ? TRUE : FALSE );
+        BOOL isConductTooLow  = FALSE;
+        BOOL isConductTooHigh = FALSE;
 
+        if ( FALSE == isROOnlyModeEnabled() )
+        {
+            isConductTooLow  = ( conductivity < MAX_COND_SENSOR_CPI_WARNING_LOW_US_PER_CM ? TRUE : FALSE );
+            isConductTooHigh = ( conductivity > MAX_COND_SENSOR_CPI_WARNING_HIGH_US_PER_CM ? TRUE : FALSE );
+        }
+        else
+        {
+            isConductTooLow  = FALSE;
+            isConductTooHigh = ( conductivity > MAX_RO_ONLY_COND_SENSOR_CPI_HIGH_US_PER_CM ? TRUE : FALSE );
+        }
+
         switch( opMode )
         {
             case DG_MODE_GENE:
@@ -317,7 +332,14 @@
 
                 if ( TRUE == isAlarmActive( ALARM_ID_INLET_WATER_CONDUCTIVITY_IN_HIGH_RANGE ) )
                 {
-                    isConductTooHigh = ( conductivity <= MIN_COND_SENSOR_CPI_WARNING_HIGH_US_PER_CM ? FALSE : TRUE );
+                    if ( FALSE == isROOnlyModeEnabled() )
+                    {
+                        isConductTooHigh = ( conductivity <= MIN_COND_SENSOR_CPI_WARNING_HIGH_US_PER_CM ? FALSE : TRUE );
+                    }
+                    else
+                    {
+                        isConductTooHigh = ( conductivity <= MIN_RO_ONLY_COND_SENSOR_CPI_HIGH_US_PER_CM ? FALSE : TRUE );
+                    }
                 }
 
                 // Per PRS 404