diff --git a/MaterialLib/MPL/Properties/TemperatureDependentFraction.h b/MaterialLib/MPL/Properties/TemperatureDependentFraction.h
index e7a2f7932d4bced1fe571c1e611f3f677756169b..a68d71a27f7aaa665a470137a5cee3e63598a6da 100644
--- a/MaterialLib/MPL/Properties/TemperatureDependentFraction.h
+++ b/MaterialLib/MPL/Properties/TemperatureDependentFraction.h
@@ -10,9 +10,6 @@
  */
 #pragma once
 
-#include <fstream>
-#include <iostream>
-
 #include "MaterialLib/MPL/Property.h"
 #include "MaterialLib/MPL/Utils/SigmoidFunction.h"
 namespace MaterialPropertyLib
diff --git a/MaterialLib/SolidModels/Ehlers.h b/MaterialLib/SolidModels/Ehlers.h
index d984878cf1397093c1fa8409c7c63f3c80cc43c1..e333206fa6989ab2431bbb1644c892af90c3d37a 100644
--- a/MaterialLib/SolidModels/Ehlers.h
+++ b/MaterialLib/SolidModels/Ehlers.h
@@ -19,7 +19,7 @@
 #pragma once
 
 #ifndef NDEBUG
-#include <ostream>
+#include <iosfwd>
 #endif
 
 #include "BaseLib/Error.h"
diff --git a/MeshLib/PropertyVector.h b/MeshLib/PropertyVector.h
index dea884ae9539c00868b71b6c688891fd7c27108b..0eb345ea0dcdb490796e9f7c291fa2c3e4411699 100644
--- a/MeshLib/PropertyVector.h
+++ b/MeshLib/PropertyVector.h
@@ -11,7 +11,6 @@
 
 #include <cassert>
 #include <iterator>
-#include <ostream>
 #include <string>
 #include <utility>
 #include <vector>
@@ -238,23 +237,6 @@ public:
         return p[component];
     }
 
-#ifndef NDEBUG
-    std::ostream& print(std::ostream& os) const
-    {
-        os << "\nPropertyVector<T*> at address: " << this << ":\n";
-        os << "\tmapping (" << size() << "):\n";
-        std::copy(this->cbegin(), this->cend(),
-                  std::ostream_iterator<std::size_t>(os, " "));
-        os << "\n\tvalues (" << _values.size() << "):\n";
-        for (std::size_t k(0); k < _values.size(); k++)
-        {
-            os << "val: " << *(_values[k]) << ", address: " << _values[k]
-               << "\n";
-        }
-        return os;
-    }
-#endif
-
 protected:
     /// @brief The constructor taking meta information for the data.
     /// @param n_prop_groups number of different property values
diff --git a/NumLib/Fem/CoordinatesMapping/ShapeMatrices.h b/NumLib/Fem/CoordinatesMapping/ShapeMatrices.h
index 33193496d7227c59a7899aa07f961e44867b8b86..556eff411197a2864f81f5d1ad769281e4f236d9 100644
--- a/NumLib/Fem/CoordinatesMapping/ShapeMatrices.h
+++ b/NumLib/Fem/CoordinatesMapping/ShapeMatrices.h
@@ -13,7 +13,7 @@
 #pragma once
 
 #include <Eigen/Core>
-#include <ostream>
+#include <iosfwd>
 
 namespace NumLib
 {
diff --git a/ProcessLib/BoundaryConditionAndSourceTerm/Python/BHEInflowPythonBoundaryCondition.h b/ProcessLib/BoundaryConditionAndSourceTerm/Python/BHEInflowPythonBoundaryCondition.h
index b5fbebb6c22701f977dadbf09c771eff78c3e342..2ba00a2bdf466442ccf9a4d1d918396f12210633 100644
--- a/ProcessLib/BoundaryConditionAndSourceTerm/Python/BHEInflowPythonBoundaryCondition.h
+++ b/ProcessLib/BoundaryConditionAndSourceTerm/Python/BHEInflowPythonBoundaryCondition.h
@@ -13,7 +13,6 @@
 #include <pybind11/pybind11.h>
 #endif  // OGS_USE_PYTHON
 #include <algorithm>
-#include <iostream>
 #include <vector>
 
 #include "BHEInflowPythonBoundaryConditionPythonSideInterface.h"
diff --git a/ProcessLib/RichardsMechanics/ComputeMicroPorosity.h b/ProcessLib/RichardsMechanics/ComputeMicroPorosity.h
index b7c3e33d48c42c462e81a4473f6be6096c2dc0ef..7596c26d78e1e4f7de50596b32efdd4e22615140 100644
--- a/ProcessLib/RichardsMechanics/ComputeMicroPorosity.h
+++ b/ProcessLib/RichardsMechanics/ComputeMicroPorosity.h
@@ -11,7 +11,7 @@
 
 #include <Eigen/LU>
 #include <cassert>
-#include <ostream>
+#include <iosfwd>
 
 #include "MaterialLib/MPL/Medium.h"
 #include "MaterialLib/MPL/Utils/FormEigenTensor.h"
diff --git a/Tests/NumLib/ODEs.h b/Tests/NumLib/ODEs.h
index d60572c38de3ea6a2f09924c3bc20afcaac91ca1..c3df0a4e1931bfcb0a281374108bd12ea5105f90 100644
--- a/Tests/NumLib/ODEs.h
+++ b/Tests/NumLib/ODEs.h
@@ -10,13 +10,11 @@
 #pragma once
 
 #include <boost/math/constants/constants.hpp>
+
 #include "MathLib/LinAlg/LinAlg.h"
 #include "MathLib/LinAlg/UnifiedMatrixSetters.h"
 #include "NumLib/ODESolver/ODESystem.h"
 
-// debug
-//#include <iostream>
-
 template <class Ode>
 class ODETraits;