Index: firmware/App/Controllers/DrainPump.c
===================================================================
diff -u -r0953a2a6940f9f096fa98cc1e8a5578deab4d8ef -r92eb8fea402c19b6d250651f9e11b088c6d9efd1
--- firmware/App/Controllers/DrainPump.c	(.../DrainPump.c)	(revision 0953a2a6940f9f096fa98cc1e8a5578deab4d8ef)
+++ firmware/App/Controllers/DrainPump.c	(.../DrainPump.c)	(revision 92eb8fea402c19b6d250651f9e11b088c6d9efd1)
@@ -46,6 +46,10 @@
 #define DRP_SPEED_ADC_TO_RPM_FACTOR            12.94               ///< conversion factor from ADC counts to RPM for Drain pump
 #define DRP_SPEED_RPM_TO_ADC_FACTOR            ( 1.0 / DRP_SPEED_ADC_TO_RPM_FACTOR )   ///< conversion factor from RPM to ADC counts for Drain pump
 
+#define DRAIN_PUMP_P_COEFFICIENT               0.005           //TODO DARA
+#define DRAIN_PUMP_I_COEFFICIENT               0.0015          //TODO DARA
+#define DRAIN_PUMP_TARGET_DELTA_PRESSURE       NEARLY_ZERO     //TODO dara
+
 /// Enumeration of drain pump states.
 typedef enum DrainPump_States
 {
@@ -110,6 +114,11 @@
 void initDrainPump( void )
 {
     stopDrainPump();
+
+    // Initialize the drain pump
+    initializePIController( PI_CONTROLLER_ID_DRAIN_PUMP, MIN_DRAIN_PUMP_RPM_TARGET,
+                            DRAIN_PUMP_P_COEFFICIENT, DRAIN_PUMP_I_COEFFICIENT,
+                            MIN_DRAIN_PUMP_RPM_TARGET, MAX_DRAIN_PUMP_RPM_TARGET );
 }
 
 /*********************************************************************//**
@@ -122,7 +131,7 @@
  * @param rpm : new target drain pump speed (in RPM).
  * @return TRUE if new target speed is set, FALSE if not
  *************************************************************************/
-BOOL setDrainPumpTargetSpeed( U32 rpm )
+BOOL setDrainPumpTargetSpeed( U32 rpm, PUMP_CONTROL_MODE_T mode )
 {
     BOOL result = FALSE;
 
@@ -131,7 +140,7 @@
     {
         drainPumpDAC = (U32)((F32)rpm * DRP_SPEED_RPM_TO_ADC_FACTOR + FLOAT_TO_INT_ROUNDUP_OFFSET);
         targetDrainPumpSpeed.data = rpm;
-        drainPumpControlMode = PUMP_CONTROL_MODE_OPEN_LOOP;
+        drainPumpControlMode = mode;
         result = TRUE;
     }
 
@@ -234,6 +243,11 @@
         SET_DRAIN_PUMP_ENABLE();
         // set drain pump control mode
         drainPumpControlModeSet = drainPumpControlMode;
+        // Check if drain pump mode is closed loop
+        if ( drainPumpControlModeSet == PUMP_CONTROL_MODE_CLOSED_LOOP )
+        {
+           resetPIController( PI_CONTROLLER_ID_DRAIN_PUMP, MIN_DRAIN_PUMP_RPM_TARGET );
+        }
         // set drain pump DAC
         drainPumpDACSet = drainPumpDAC;
         setFPGADrainPumpSpeed( drainPumpDACSet );
@@ -263,7 +277,12 @@
     {
         if ( drainPumpControlModeSet == PUMP_CONTROL_MODE_CLOSED_LOOP )
         {
-            // TODO - will drain pump have a closed loop?
+            F32 inletDrainPressure = getMeasuredDGPressure ( PRESSURE_SENSOR_DRAIN_PUMP_INLET );
+            F32 outletDrainPressure = getMeasuredDGPressure ( PRESSURE_SENSOR_DRAIN_PUMP_OUTLET );
+            F32 pressureDiff = fabs( inletDrainPressure - outletDrainPressure );
+            F32 rpm = runPIController( PI_CONTROLLER_ID_DRAIN_PUMP, DRAIN_PUMP_TARGET_DELTA_PRESSURE, pressureDiff );
+            drainPumpDAC = (U32)((F32)rpm * DRP_SPEED_RPM_TO_ADC_FACTOR + FLOAT_TO_INT_ROUNDUP_OFFSET);
+            setFPGADrainPumpSpeed( drainPumpDAC );
         }
         drainControlTimerCounter = 0;
     }
@@ -465,7 +484,7 @@
         targetDrainPumpSpeed.ovInitData = targetDrainPumpSpeed.data; // backup current target pressure
         targetDrainPumpSpeed.ovData = value;
         targetDrainPumpSpeed.override = OVERRIDE_KEY;
-        result = setDrainPumpTargetSpeed( value );
+        result = setDrainPumpTargetSpeed( value, PUMP_CONTROL_MODE_OPEN_LOOP );
     }
 
     return result;
@@ -490,7 +509,7 @@
         targetDrainPumpSpeed.override = OVERRIDE_RESET;
         targetDrainPumpSpeed.ovInitData = 0;
         targetDrainPumpSpeed.ovData = 0;
-        result = setDrainPumpTargetSpeed( targetDrainPumpSpeed.data );
+        result = setDrainPumpTargetSpeed( targetDrainPumpSpeed.data, PUMP_CONTROL_MODE_OPEN_LOOP );
     }
 
     return result;
Index: firmware/App/Controllers/DrainPump.h
===================================================================
diff -u -r2496e9225fa1b2c627d625def02515a0f0dd5793 -r92eb8fea402c19b6d250651f9e11b088c6d9efd1
--- firmware/App/Controllers/DrainPump.h	(.../DrainPump.h)	(revision 2496e9225fa1b2c627d625def02515a0f0dd5793)
+++ firmware/App/Controllers/DrainPump.h	(.../DrainPump.h)	(revision 92eb8fea402c19b6d250651f9e11b088c6d9efd1)
@@ -38,7 +38,7 @@
 void execDrainPumpMonitor( void );
 void execDrainPumpController( void );
 
-BOOL setDrainPumpTargetSpeed( U32 rpm );
+BOOL setDrainPumpTargetSpeed( U32 rpm, PUMP_CONTROL_MODE_T mode );
 void signalDrainPumpHardStop( void );
 
 SELF_TEST_STATUS_T execDrainPumpTest( void );
Index: firmware/App/Controllers/ROPump.h
===================================================================
diff -u -r1e044a958c655d09fed725cfbc9808319b642d13 -r92eb8fea402c19b6d250651f9e11b088c6d9efd1
--- firmware/App/Controllers/ROPump.h	(.../ROPump.h)	(revision 1e044a958c655d09fed725cfbc9808319b642d13)
+++ firmware/App/Controllers/ROPump.h	(.../ROPump.h)	(revision 92eb8fea402c19b6d250651f9e11b088c6d9efd1)
@@ -32,8 +32,8 @@
 #define MAX_RO_PRESSURE                 140             ///< Maximum target RO outlet pressure (in PSI). //TODO remove
 #define MIN_RO_PRESSURE                 100             ///< Minimum target RO outlet pressure (in PSI). //TODO remove
 
-#define MAX_RO_FLOWRATE                 2000
-#define MIN_RO_FLOWRATE                 300
+#define MAX_RO_FLOWRATE                 2000            //TODO dara
+#define MIN_RO_FLOWRATE                 300             //TODO dara
 
 // ********** public function prototypes **********
 
Index: firmware/App/Modes/ModeDrain.c
===================================================================
diff -u -rd8c4c523f0551a95c3c6ee5cf5b693f75161d163 -r92eb8fea402c19b6d250651f9e11b088c6d9efd1
--- firmware/App/Modes/ModeDrain.c	(.../ModeDrain.c)	(revision d8c4c523f0551a95c3c6ee5cf5b693f75161d163)
+++ firmware/App/Modes/ModeDrain.c	(.../ModeDrain.c)	(revision 92eb8fea402c19b6d250651f9e11b088c6d9efd1)
@@ -67,7 +67,7 @@
 
     // set initial actuator states
     setValveState( VDR, VALVE_STATE_DRAIN_C_TO_NO );
-    setDrainPumpTargetSpeed( TARGET_DRAIN_PUMP_RPM );
+    setDrainPumpTargetSpeed( TARGET_DRAIN_PUMP_RPM, PUMP_CONTROL_MODE_OPEN_LOOP );
 }
 
 /*********************************************************************//**
@@ -123,7 +123,7 @@
     // if we've reached our target drain to volume (by weight), we're done draining - go back to re-circ mode
     if ( getReservoirDrainVolumeTargetMl() >= getLoadCellFilteredWeight( drainWeightLoadCell ) )
     {
-        setDrainPumpTargetSpeed( 0 );
+        setDrainPumpTargetSpeed( 0, PUMP_CONTROL_MODE_OPEN_LOOP );
         requestNewOperationMode( DG_MODE_CIRC );
     }
 
Index: firmware/App/Modes/ModeHeatDisinfect.c
===================================================================
diff -u -r1e044a958c655d09fed725cfbc9808319b642d13 -r92eb8fea402c19b6d250651f9e11b088c6d9efd1
--- firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision 1e044a958c655d09fed725cfbc9808319b642d13)
+++ firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision 92eb8fea402c19b6d250651f9e11b088c6d9efd1)
@@ -211,7 +211,7 @@
     setValveState ( VRF, VALVE_STATE_R2_C_TO_NO );
 
     setROPumpTargetPressure( 0, PUMP_CONTROL_MODE_CLOSED_LOOP );
-    setDrainPumpTargetSpeed( 0 );
+    setDrainPumpTargetSpeed( 0, PUMP_CONTROL_MODE_OPEN_LOOP );
     stopInletUVReactor();
     stopOutletUVReactor();
     stopPrimaryHeater();
@@ -294,7 +294,7 @@
     //TODO composition pumps
 
     setROPumpTargetPressure( 0, PUMP_CONTROL_MODE_CLOSED_LOOP );
-    setDrainPumpTargetSpeed( 0 );
+    setDrainPumpTargetSpeed( 0, PUMP_CONTROL_MODE_OPEN_LOOP );
     stopInletUVReactor();
     stopOutletUVReactor();
     stopPrimaryHeater();
Index: firmware/App/Services/PIControllers.c
===================================================================
diff -u -r3cc737c39b4440e18abab95ef2f8b6aef13acba9 -r92eb8fea402c19b6d250651f9e11b088c6d9efd1
--- firmware/App/Services/PIControllers.c	(.../PIControllers.c)	(revision 3cc737c39b4440e18abab95ef2f8b6aef13acba9)
+++ firmware/App/Services/PIControllers.c	(.../PIControllers.c)	(revision 92eb8fea402c19b6d250651f9e11b088c6d9efd1)
@@ -56,6 +56,8 @@
 {   // Kp   Ki  uMax  uMin  ref meas  err  esw esum ctrl
 
     { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 },  // PI_CONTROLLER_ID_RO_PUMP
+    { 0.0, 0.0, 0.99, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 },  // P_CONTROLLER_ID_RO_PUMP_RAMP_UP
+    { 0.0, 0.0, 3000, 300, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 },  // PI_CONTROLLER_ID_DRAIN_PUMP
     { 0.0, 0.0, 0.89, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 },  // PI_CONTROLLER_ID_PRIMARY_HEATER
     { 0.0, 0.0, 0.50, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 }   // PI_CONTROLLER_ID_TRIMMER_HEATER
 };
Index: firmware/App/Services/PIControllers.h
===================================================================
diff -u -r1e044a958c655d09fed725cfbc9808319b642d13 -r92eb8fea402c19b6d250651f9e11b088c6d9efd1
--- firmware/App/Services/PIControllers.h	(.../PIControllers.h)	(revision 1e044a958c655d09fed725cfbc9808319b642d13)
+++ firmware/App/Services/PIControllers.h	(.../PIControllers.h)	(revision 92eb8fea402c19b6d250651f9e11b088c6d9efd1)
@@ -33,7 +33,8 @@
 typedef enum ControllerList
 {
     PI_CONTROLLER_ID_RO_PUMP = 0,                   ///< RO Pump controller.
-    P_CONTROLLER_ID_RO_PUMP_RAMP_UP,                ///< RO Pump controller during ramp up time
+    P_CONTROLLER_ID_RO_PUMP_RAMP_UP,                ///< RO Pump controller during ramp up time.
+    PI_CONTROLLER_ID_DRAIN_PUMP,                    ///< Drain Pump controller.
     PI_CONTROLLER_ID_PRIMARY_HEATER,                ///< Primary Heater controller.
     PI_CONTROLLER_ID_TRIMMER_HEATER,                ///< Trimmer Heater controller.
     NUM_OF_PI_CONTROLLERS_IDS                       ///< Number of PI controllers.