diff --git a/dumux/common/boundarytypes.hh b/dumux/common/boundarytypes.hh
index d11ddf6de4dea68afd64066da6f01fa7730c6101..dbce125fe98e807ca46820353c0b62a16ced8820 100644
--- a/dumux/common/boundarytypes.hh
+++ b/dumux/common/boundarytypes.hh
@@ -117,6 +117,7 @@ public:
     /*!
      * \brief Set all boundary conditions to Neumann.
      */
+    [[deprecated("Will be removed after release 3.4")]]
     void setAllOutflow()
     {
         for (int eqIdx = 0; eqIdx < numEq; ++eqIdx)
@@ -181,6 +182,7 @@ public:
      * \param eqIdx The index of the equation on which the outflow
      *              condition applies.
      */
+    [[deprecated("Will be removed after release 3.4")]]
     void setOutflow(int eqIdx)
     {
         resetEq(eqIdx);
@@ -308,6 +310,7 @@ public:
      *
      * \param eqIdx The index of the equation
      */
+    [[deprecated("Will be removed after release 3.4")]]
     bool isOutflow(unsigned eqIdx) const
     { return boundaryInfo_[eqIdx].isOutflow; }
 
@@ -315,6 +318,7 @@ public:
      * \brief Returns true if some equation is used to specify an
      *        outflow condition.
      */
+    [[deprecated("Will be removed after release 3.4")]]
     bool hasOutflow() const
     {
         return std::any_of(boundaryInfo_.begin(),
diff --git a/dumux/discretization/box/elementboundarytypes.hh b/dumux/discretization/box/elementboundarytypes.hh
index ac9422771db7126316859f1ec704e91a5d807ddb..f36fc097bf892beb359bc06359e5dc4a016a95e9 100644
--- a/dumux/discretization/box/elementboundarytypes.hh
+++ b/dumux/discretization/box/elementboundarytypes.hh
@@ -26,6 +26,7 @@
 
 #include <cassert>
 #include <vector>
+#include <dune/common/deprecated.hh>
 
 namespace Dumux {
 
@@ -72,7 +73,9 @@ public:
 
                 hasDirichlet_ = hasDirichlet_ || vertexBCTypes_[scvIdxLocal].hasDirichlet();
                 hasNeumann_ = hasNeumann_ || vertexBCTypes_[scvIdxLocal].hasNeumann();
+DUNE_NO_DEPRECATED_BEGIN
                 hasOutflow_ = hasOutflow_ || vertexBCTypes_[scvIdxLocal].hasOutflow();
+DUNE_NO_DEPRECATED_END
             }
         }
     }
@@ -95,6 +98,7 @@ public:
      * \brief Returns whether the element potentially features an
      *        outflow boundary segment.
      */
+    [[deprecated("Will be removed after release 3.4")]]
     bool hasOutflow() const
     { return hasOutflow_; }