diff --git a/src/userInputParameters/load_BC_list.cc b/src/userInputParameters/load_BC_list.cc
index bf423507f..13cc3b67b 100644
--- a/src/userInputParameters/load_BC_list.cc
+++ b/src/userInputParameters/load_BC_list.cc
@@ -1,24 +1,31 @@
+// ------------------------------------------------------------------------
+// Method to extract the list of boundary conditions from input parameters
+// and store them in BC_list object
+// ------------------------------------------------------------------------
+
+#include <deal.II/base/exceptions.h>
+
 #include "../../include/userInputParameters.h"
 
-// ==========================================================================================
-// Method to extract the list of boundary conditions
-// ==========================================================================================
 template <int dim>
 void
 userInputParameters<dim>::load_BC_list(std::vector<std::string> list_of_BCs)
 {
-  // Load the BC information from the strings into a varBCs object
-  // Move this to a new method and write a unit test for it!!!!
-
+  // Loop over the list of boundary conditions specified in parameters
+  // and provided in the input list_of_BCs. Process the BCs and place
+  // them into the vector BC_list
   std::vector<std::string> temp;
-
   for (unsigned int i = 0; i < list_of_BCs.size(); i++)
     {
+      // Ensure all variables have BCs specified in parameters.prm
+      AssertThrow(!list_of_BCs[i].empty(),
+                  dealii::ExcMessage(std::string("Boundary condition not specified.")));
+
       varBCs<dim> newBC;
       temp = dealii::Utilities::split_string_list(list_of_BCs[i]);
 
-      // If there is only one BC listed, make another dim*2-1 copies of it so
-      // that the same BC is applied for all boundaries
+      // If there is only one BC listed, make another dim*2-1 copies of it so that
+      // the same BC is applied for all boundaries
       if (temp.size() == 1)
         {
           for (unsigned int boundary = 0; boundary < (dim * 2 - 1); boundary++)
@@ -27,76 +34,64 @@ userInputParameters<dim>::load_BC_list(std::vector<std::string> list_of_BCs)
             }
         }
 
-      // Load the BC for each boundary into 'newBC'
-      for (unsigned int i = 0; i < (2 * dim); i++)
+      // Load the BC for each boundary into 'newBC'.
+      for (unsigned int j = 0; j < (2 * dim); j++)
         {
-          if (boost::iequals(temp[i], "NATURAL"))
+          if (boost::iequals(temp[j], "NATURAL"))
             {
               newBC.var_BC_type.push_back(NATURAL);
               newBC.var_BC_val.push_back(0.0);
             }
-          else if (boost::iequals(temp[i], "PERIODIC"))
+          else if (boost::iequals(temp[j], "PERIODIC"))
             {
               newBC.var_BC_type.push_back(PERIODIC);
               newBC.var_BC_val.push_back(0.0);
             }
-          else if (boost::iequals(temp[i], "NON_UNIFORM_DIRICHLET"))
+          else if (boost::iequals(temp[j], "NON_UNIFORM_DIRICHLET"))
             {
               newBC.var_BC_type.push_back(NON_UNIFORM_DIRICHLET);
               newBC.var_BC_val.push_back(0.0);
             }
-          else if (boost::iequals(temp[i].substr(0, 9), "DIRICHLET"))
+          else if (boost::iequals(temp[j].substr(0, 9), "DIRICHLET"))
             {
               newBC.var_BC_type.push_back(DIRICHLET);
-              std::string dirichlet_val = temp[i].substr(10, temp[i].size());
+              std::string dirichlet_val = temp[j].substr(10, temp[j].size());
               dirichlet_val             = dealii::Utilities::trim(dirichlet_val);
               newBC.var_BC_val.push_back(
                 dealii::Utilities::string_to_double(dirichlet_val));
             }
-          else if (boost::iequals(temp[i].substr(0, 7), "NEUMANN"))
+          else if (boost::iequals(temp[j].substr(0, 7), "NEUMANN"))
             {
               newBC.var_BC_type.push_back(NEUMANN);
-              std::string neumann_val = temp[i].substr(8, temp[i].size());
+              std::string neumann_val = temp[j].substr(8, temp[j].size());
               neumann_val             = dealii::Utilities::trim(neumann_val);
               newBC.var_BC_val.push_back(
                 dealii::Utilities::string_to_double(neumann_val));
             }
           else
             {
-              std::cout << temp[i].substr(0, 8) << std::endl;
+              std::cout << temp[j].substr(0, 8) << std::endl;
               std::cout << "Error: Boundary conditions specified improperly."
                         << std::endl;
               abort();
             }
+
+          // If periodic BCs are used, ensure they are applied on both sides of
+          // domain
+          if (j % 2 == 0)
+            {
+              AssertThrow(!((boost::iequals(temp[j], "PERIODIC") &&
+                             !boost::iequals(temp[j + 1], "PERIODIC")) ||
+                            (!boost::iequals(temp[j], "PERIODIC") &&
+                             boost::iequals(temp[j + 1], "PERIODIC"))),
+                          dealii::ExcMessage(
+                            std::string("Periodic boundary condition must be "
+                                        "specified on both sides of domain")));
+            }
         }
+      // Append BCs for current field to total list
       BC_list.push_back(newBC);
-
-      // Validate input using something like this:
-      // try{
-      //     if ((BC_type_dim1_min == "PERIODIC") && (BC_type_dim1_max !=
-      //     "PERIODIC")){
-      //         throw 0;
-      //     }
-      //     if ((BC_type_dim2_min == "PERIODIC") && (BC_type_dim2_max !=
-      //     "PERIODIC")){
-      //         throw 0;
-      //     }
-      //     if ((BC_type_dim3_min == "PERIODIC") && (BC_type_dim3_max !=
-      //     "PERIODIC")){
-      //         throw 0;
-      //     }
-      // }
-      // catch (int e){
-      //     if (e == 0){
-      //         std::cout << "Error: For periodic BCs, both faces for a given
-      //         direction must be set as periodic. "
-      //                 "Please check the BCs that are set in ICs_and_BCs.h."
-      //                 << std::endl;
-      //     }
-      //     abort();
-      // }
     }
 }
 
-// Template instantiations
-#include "../../include/userInputParameters_template_instantiations.h"
+#include "../../include/userInputParameters_template_instantiations.h"
\ No newline at end of file