Index: firmware/App/Monitors/WaterQualityMonitor.c
===================================================================
diff -u -r3a5cc585b69ffa194e3601a005915d23b48bd865 -r44dbba513dffd7b1a997f873426407dbfc4163d1
--- firmware/App/Monitors/WaterQualityMonitor.c	(.../WaterQualityMonitor.c)	(revision 3a5cc585b69ffa194e3601a005915d23b48bd865)
+++ firmware/App/Monitors/WaterQualityMonitor.c	(.../WaterQualityMonitor.c)	(revision 44dbba513dffd7b1a997f873426407dbfc4163d1)
@@ -1,17 +1,17 @@
 /**************************************************************************
 *
-* Copyright (c) 2024-2024 Diality Inc. - All Rights Reserved.
+* Copyright (c) 2025-2025 Diality Inc. - All Rights Reserved.
 *
 * THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
 * WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
 *
 * @file    WaterQualityMonitor.c
 *
-* @author  (last)      Sean Nash
-* @date    (last)      21-Nov-2024
+* @author  (last)      Michael Garthwaite
+* @date    (last)      01-Aug-2025
 *
-* @author  (original)  Sean Nash
-* @date    (original)  21-Nov-2024
+* @author  (original)  Michael Garthwaite
+* @date    (original)  25-Jul-2025
 *
 ***************************************************************************/
 
@@ -53,6 +53,7 @@
 #define INLET_WATER_COND_OUT_OF_RANGE_TIMEOUT_MS            ( 5 * MS_PER_SECOND )                                   ///< Persistence period for conductivity out of range error in milliseconds.
 #define INLET_WATER_COND_OUT_OF_RANGE_CLEAR_MS              ( 5 * MS_PER_SECOND )                                   ///< Persistence period for conductivity out of range clear in milliseconds.
 #define INLET_CONDUCTIVITY_HIGH_THRESHOLD_US                2000.0F                                                 ///< Maximum allowed outlet conductivity in uS/cm.
+#define MIN_RO_REJECTION_RATIO_PCT                          90.0F                                                   ///< Minimum RO rejection ration in percentage
 
 // ********** private data **********
 
@@ -230,7 +231,27 @@
     checkPersistentAlarm( ALARM_ID_FP_RO_OUTLET_CONDUCTIVITY_HIGH_RANGE, isConductivityOutOfLowRange, conductivityP18, OUTLET_CONDUCTIVITY_HIGH_THRESHOLD_US );
 }
 
+/*********************************************************************//**
+ * @brief
+ * The checkRORejectionRatio function checks the RO rejection ratio
+ * alarm if the rejection ratio is out of range.
+ * @details \b Inputs: roRRAvg
+ * @details \b Outputs: none
+ * @details \b Alarms: ALARM_ID_FP_REJECTION_RATIO_LOW_RANGE when
+ * RO rejection ratio goes below allowed rejection ratio limit.
+ * @return none
+ *************************************************************************/
+void checkRORejectionRatio( void )
+{
+    F32 avgRORR = getRORRAverage();
+    // Alarm if the filtered average is less than allowed RO rejection limit
+    if ( avgRORR < MIN_RO_REJECTION_RATIO_PCT )
+    {
+        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_FP_REJECTION_RATIO_LOW_RANGE, avgRORR, MIN_RO_REJECTION_RATIO_PCT)
+    }
+}
 
+
 /*************************************************************************
  *                       TEST SUPPORT FUNCTIONS
  *************************************************************************/