diff --git a/internal/runner/abstract_manager.go b/internal/runner/abstract_manager.go
index 6fa06fe..8e9c9cd 100644
--- a/internal/runner/abstract_manager.go
+++ b/internal/runner/abstract_manager.go
@@ -64,10 +64,14 @@ func (n *AbstractManager) EnvironmentStatistics() map[dto.EnvironmentID]*dto.Sta
 			ID:                 int(e.ID()),
 			PrewarmingPoolSize: e.PrewarmingPoolSize(),
 			IdleRunners:        uint(e.IdleRunnerCount()),
-			UsedRunners:        0, // Adjusted later as the information is present in the specific runner manager.
+			UsedRunners:        0, // Increased below.
 		}
 	}
 
+	for _, r := range n.usedRunners.List() {
+		environments[r.Environment()].UsedRunners++
+	}
+
 	return environments
 }
 
diff --git a/internal/runner/aws_manager.go b/internal/runner/aws_manager.go
index 5487779..d7889a3 100644
--- a/internal/runner/aws_manager.go
+++ b/internal/runner/aws_manager.go
@@ -45,22 +45,3 @@ func (a AWSRunnerManager) Return(r Runner) error {
 	}
 	return nil
 }
-
-// EnvironmentStatistics returns only the used runner for each environment as the prewarming is handled
-// by AWS transparently.
-func (a AWSRunnerManager) EnvironmentStatistics() map[dto.EnvironmentID]*dto.StatisticalExecutionEnvironmentData {
-	environments := a.AbstractManager.EnvironmentStatistics()
-
-	for _, r := range a.usedRunners.List() {
-		workload, isAWSRunner := r.(*AWSFunctionWorkload)
-		if !isAWSRunner {
-			log.WithField("workload", workload).Error("Stored runners must be AWS runner")
-			continue
-		}
-
-		environmentID := workload.environment.ID()
-		environments[environmentID].UsedRunners++
-	}
-
-	return environments
-}
diff --git a/internal/runner/aws_runner.go b/internal/runner/aws_runner.go
index 6f2641d..318c456 100644
--- a/internal/runner/aws_runner.go
+++ b/internal/runner/aws_runner.go
@@ -61,6 +61,10 @@ func (w *AWSFunctionWorkload) ID() string {
 	return w.id
 }
 
+func (w *AWSFunctionWorkload) Environment() dto.EnvironmentID {
+	return w.environment.ID()
+}
+
 func (w *AWSFunctionWorkload) MappedPorts() []*dto.MappedPort {
 	return []*dto.MappedPort{}
 }
diff --git a/internal/runner/nomad_manager.go b/internal/runner/nomad_manager.go
index e971d41..c9f77ba 100644
--- a/internal/runner/nomad_manager.go
+++ b/internal/runner/nomad_manager.go
@@ -34,19 +34,6 @@ func NewNomadRunnerManager(apiClient nomad.ExecutorAPI, ctx context.Context) *No
 	return m
 }
 
-func (m *NomadRunnerManager) EnvironmentStatistics() map[dto.EnvironmentID]*dto.StatisticalExecutionEnvironmentData {
-	environments := m.AbstractManager.EnvironmentStatistics()
-
-	for _, r := range m.usedRunners.List() {
-		id, err := nomad.EnvironmentIDFromRunnerID(r.ID())
-		if err != nil {
-			log.WithError(err).Error("Stored runners must have correct IDs")
-		}
-		environments[id].UsedRunners++
-	}
-	return environments
-}
-
 func (m *NomadRunnerManager) Claim(environmentID dto.EnvironmentID, duration int) (Runner, error) {
 	environment, ok := m.environments.Get(environmentID)
 	if !ok {
diff --git a/internal/runner/nomad_runner.go b/internal/runner/nomad_runner.go
index 3a79eef..bb01090 100644
--- a/internal/runner/nomad_runner.go
+++ b/internal/runner/nomad_runner.go
@@ -66,6 +66,14 @@ func (r *NomadJob) ID() string {
 	return r.id
 }
 
+func (r *NomadJob) Environment() dto.EnvironmentID {
+	id, err := nomad.EnvironmentIDFromRunnerID(r.ID())
+	if err != nil {
+		log.WithError(err).Error("Runners must have correct IDs")
+	}
+	return id
+}
+
 func (r *NomadJob) MappedPorts() []*dto.MappedPort {
 	ports := make([]*dto.MappedPort, 0, len(r.portMappings))
 	for _, portMapping := range r.portMappings {
diff --git a/internal/runner/runner.go b/internal/runner/runner.go
index cd09de8..066b784 100644
--- a/internal/runner/runner.go
+++ b/internal/runner/runner.go
@@ -19,6 +19,9 @@ type Runner interface {
 	// ID returns the id of the runner.
 	ID() string
 
+	// Environment returns the id of the Environment to which the Runner belongs.
+	Environment() dto.EnvironmentID
+
 	// MappedPorts returns the mapped ports of the runner.
 	MappedPorts() []*dto.MappedPort
 
diff --git a/internal/runner/runner_mock.go b/internal/runner/runner_mock.go
index f44aa0f..5879ceb 100644
--- a/internal/runner/runner_mock.go
+++ b/internal/runner/runner_mock.go
@@ -1,4 +1,4 @@
-// Code generated by mockery v0.0.0-dev. DO NOT EDIT.
+// Code generated by mockery v2.10.4. DO NOT EDIT.
 
 package runner
 
@@ -32,6 +32,20 @@ func (_m *RunnerMock) Destroy() error {
 	return r0
 }
 
+// Environment provides a mock function with given fields:
+func (_m *RunnerMock) Environment() dto.EnvironmentID {
+	ret := _m.Called()
+
+	var r0 dto.EnvironmentID
+	if rf, ok := ret.Get(0).(func() dto.EnvironmentID); ok {
+		r0 = rf()
+	} else {
+		r0 = ret.Get(0).(dto.EnvironmentID)
+	}
+
+	return r0
+}
+
 // ExecuteInteractively provides a mock function with given fields: id, stdin, stdout, stderr
 func (_m *RunnerMock) ExecuteInteractively(id string, stdin io.ReadWriter, stdout io.Writer, stderr io.Writer) (<-chan ExitInfo, context.CancelFunc, error) {
 	ret := _m.Called(id, stdin, stdout, stderr)