Index: Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs
===================================================================
diff -u -rc4a957f939912203096b6ba3e09f43950414389a -rbc869d73deeaf43feda4141583194e52b9f23d6f
--- Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs	(.../PipingPlugin.cs)	(revision c4a957f939912203096b6ba3e09f43950414389a)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs	(.../PipingPlugin.cs)	(revision bc869d73deeaf43feda4141583194e52b9f23d6f)
@@ -76,7 +76,7 @@
             yield return new PropertyInfo<PipingInputContext, PipingInputContextProperties>
             {
                 CreateInstance = context => new PipingInputContextProperties(context,
-                                                                             () => GetNormativeAssessmentLevel(context.PipingCalculation),
+                                                                             () => GetNormativeAssessmentLevel(context.AssessmentSection, context.PipingCalculation),
                                                                              new ObservablePropertyChangeHandler(context.PipingCalculation, context.WrappedData))
             };
             yield return new PropertyInfo<PipingOutputContext, PipingOutputProperties>
@@ -617,9 +617,9 @@
 
         #endregion
 
-        private static RoundedDouble GetNormativeAssessmentLevel(PipingCalculation calculation)
+        private static RoundedDouble GetNormativeAssessmentLevel(IAssessmentSection assessmentSection, PipingCalculation calculation)
         {
-            return calculation.InputParameters.HydraulicBoundaryLocation?.DesignWaterLevelCalculation1.Output?.Result ?? RoundedDouble.NaN;
+            return assessmentSection.GetNormativeAssessmentLevel(calculation.InputParameters.HydraulicBoundaryLocation);
         }
 
         #region PipingFailureMechanismContext TreeNodeInfo
@@ -809,7 +809,7 @@
 
         private static void Validate(PipingCalculationScenarioContext context)
         {
-            PipingCalculationService.Validate(context.WrappedData, GetNormativeAssessmentLevel(context.WrappedData));
+            PipingCalculationService.Validate(context.WrappedData, GetNormativeAssessmentLevel(context.AssessmentSection, context.WrappedData));
         }
 
         private static string ValidateAllDataAvailableAndGetErrorMessage(PipingCalculationScenarioContext context)
@@ -821,7 +821,7 @@
         {
             ActivityProgressDialogRunner.Run(Gui.MainWindow,
                                              new PipingCalculationActivity(calculation,
-                                                                           GetNormativeAssessmentLevel(calculation),
+                                                                           GetNormativeAssessmentLevel(context.AssessmentSection, calculation),
                                                                            context.FailureMechanism.PipingProbabilityAssessmentInput,
                                                                            context.AssessmentSection.FailureMechanismContribution.Norm,
                                                                            context.FailureMechanism.Contribution));