diff --git a/examples/swat-s1/physical_process.py b/examples/swat-s1/physical_process.py
index d0026c6..1605114 100644
--- a/examples/swat-s1/physical_process.py
+++ b/examples/swat-s1/physical_process.py
@@ -10,9 +10,9 @@
 
 from minicps.devices import Tank
 
-from utils import PUMP_FLOWRATE_IN, PUMP_FLOWRATE_OUT
+from utils import PUMP_FLOWRATE_IN, PUMP_FLOWRATE_OUT, TANK2_INFLOW, TANK2_OUTFLOW
 from utils import TANK_HEIGHT, TANK_SECTION, TANK_DIAMETER
-from utils import LIT_101_M, RWT_INIT_LEVEL
+from utils import LIT_101_M, RWT_INIT_LEVEL, LIT_301_M
 from utils import STATE, PP_PERIOD_SEC, PP_PERIOD_HOURS, PP_SAMPLES
 import pandas as pd
 
@@ -39,6 +39,7 @@ def pre_loop(self):
         self.set(MV101, 1)
         self.set(P101, 0)
         self.level = self.set(LIT101, 0.800)
+        self.level2 = self.set(LIT301,0.850)
         # SPHINX_SWAT_TUTORIAL STATE INIT)
 
         # test underflow
@@ -55,6 +56,7 @@ def main_loop(self):
         while(count <= PP_SAMPLES):
 
             new_level = self.level
+            tank2_level = self.level2
 
             # compute water volume
             water_volume = self.section * new_level
@@ -76,7 +78,9 @@ def main_loop(self):
                 outflow = PUMP_FLOWRATE_OUT * PP_PERIOD_HOURS
                 # print("DEBUG RawWaterTank outflow: ", outflow)
                 water_volume -= outflow
+                tank2_level += TANK2_INFLOW
             else:
+                tank2_level -= TANK2_OUTFLOW
                 self.set(FIT201, 0.00)
 
             # compute new water_level
@@ -90,11 +94,16 @@ def main_loop(self):
             print("DEBUG new_level: %.5f \t delta: %.5f" % (
                 new_level, new_level - self.level))
             self.level = self.set(LIT101, new_level)
+            self.level2 = self.set(LIT301, tank2_level)
 
             # 988 sec starting from 0.500 m
             if new_level >= LIT_101_M['HH']:
                 print('DEBUG RawWaterTank above HH count: ', count)
                 break
+            
+            if tank2_level >= LIT_301_M['HH']:
+                print('DEBUG WaterTank2 above HH count: ', count)
+                break
 
             # 367 sec starting from 0.500 m
             elif new_level <= LIT_101_M['LL']:
diff --git a/examples/swat-s1/utils.py b/examples/swat-s1/utils.py
index ad99f67..9f07ac7 100644
--- a/examples/swat-s1/utils.py
+++ b/examples/swat-s1/utils.py
@@ -30,6 +30,8 @@
 TANK_SECTION = 1.5             # m^2
 PUMP_FLOWRATE_IN = 2.55        # m^3/h spec say btw 2.2 and 2.4
 PUMP_FLOWRATE_OUT = 2.45       # m^3/h spec say btw 2.2 and 2.4
+TANK2_INFLOW = 0.45/1000       # Simplification from Hybrid model
+TANK2_OUTFLOW = 0.15/1000
 
 # periods in msec
 # R/W = Read or Write