diff --git a/src/python/grpcio_health_checking/grpc_health/v1/health.py b/src/python/grpcio_health_checking/grpc_health/v1/health.py
index f135ffbb645..c1bb998df90 100644
--- a/src/python/grpcio_health_checking/grpc_health/v1/health.py
+++ b/src/python/grpcio_health_checking/grpc_health/v1/health.py
@@ -60,15 +60,15 @@ class _Watcher():
             self._condition.notify()
 
 
-def _watcher_to_on_next_adapter(watcher):
+def _watcher_to_on_next_callback_adapter(watcher):
 
-    def on_next(response):
+    def on_next_callback(response):
         if response is None:
             watcher.close()
         else:
             watcher.add(response)
 
-    return on_next
+    return on_next_callback
 
 
 class HealthServicer(_health_pb2_grpc.HealthServicer):
@@ -83,12 +83,12 @@ class HealthServicer(_health_pb2_grpc.HealthServicer):
         self.Watch.__func__.experimental_non_blocking = experimental_non_blocking
         self.Watch.__func__.experimental_thread_pool = experimental_thread_pool
 
-    def _on_close_callback(self, on_next, service):
+    def _on_close_callback(self, on_next_callback, service):
 
         def callback():
             with self._lock:
-                self._on_next_callbacks[service].remove(on_next)
-            on_next(None)
+                self._on_next_callbacks[service].remove(on_next_callback)
+            on_next_callback(None)
 
         return callback
 
@@ -102,24 +102,26 @@ class HealthServicer(_health_pb2_grpc.HealthServicer):
                 return _health_pb2.HealthCheckResponse(status=status)
 
     # pylint: disable=arguments-differ
-    def Watch(self, request, context, on_next=None):
+    def Watch(self, request, context, on_next_callback=None):
         blocking_watcher = None
-        if on_next is None:
+        if on_next_callback is None:
             # The server does not support the experimental_non_blocking
             # parameter. For backwards compatibility, return a blocking response
             # generator.
             blocking_watcher = _Watcher()
-            on_next = _watcher_to_on_next_adapter(blocking_watcher)
+            on_next_callback = _watcher_to_on_next_callback_adapter(
+                blocking_watcher)
         service = request.service
         with self._lock:
             status = self._server_status.get(service)
             if status is None:
                 status = _health_pb2.HealthCheckResponse.SERVICE_UNKNOWN  # pylint: disable=no-member
-            on_next(_health_pb2.HealthCheckResponse(status=status))
+            on_next_callback(_health_pb2.HealthCheckResponse(status=status))
             if service not in self._on_next_callbacks:
                 self._on_next_callbacks[service] = set()
-            self._on_next_callbacks[service].add(on_next)
-            context.add_callback(self._on_close_callback(on_next, service))
+            self._on_next_callbacks[service].add(on_next_callback)
+            context.add_callback(
+                self._on_close_callback(on_next_callback, service))
         return blocking_watcher
 
     def set(self, service, status):
@@ -133,5 +135,6 @@ class HealthServicer(_health_pb2_grpc.HealthServicer):
         with self._lock:
             self._server_status[service] = status
             if service in self._on_next_callbacks:
-                for on_next in self._on_next_callbacks[service]:
-                    on_next(_health_pb2.HealthCheckResponse(status=status))
+                for on_next_callback in self._on_next_callbacks[service]:
+                    on_next_callback(
+                        _health_pb2.HealthCheckResponse(status=status))
diff --git a/src/python/grpcio_tests/tests/health_check/_health_servicer_test.py b/src/python/grpcio_tests/tests/health_check/_health_servicer_test.py
index 3b8ee883bbe..2b1d17adfb0 100644
--- a/src/python/grpcio_tests/tests/health_check/_health_servicer_test.py
+++ b/src/python/grpcio_tests/tests/health_check/_health_servicer_test.py
@@ -23,6 +23,7 @@ from grpc_health.v1 import health_pb2
 from grpc_health.v1 import health_pb2_grpc
 
 from tests.unit import test_common
+from tests.unit import _thread_pool
 from tests.unit.framework.common import test_constants
 
 from six.moves import queue
@@ -42,8 +43,11 @@ class BaseWatchTests(object):
 
     class WatchTests(unittest.TestCase):
 
-        def start_server(self, servicer):
-            self._servicer = servicer
+        def start_server(self, non_blocking=False, thread_pool=None):
+            self._thread_pool = thread_pool
+            self._servicer = health.HealthServicer(
+                experimental_non_blocking=non_blocking,
+                experimental_thread_pool=thread_pool)
             self._servicer.set('', health_pb2.HealthCheckResponse.SERVING)
             self._servicer.set(_SERVING_SERVICE,
                                health_pb2.HealthCheckResponse.SERVING)
@@ -80,6 +84,9 @@ class BaseWatchTests(object):
             thread.join()
             self.assertTrue(response_queue.empty())
 
+            if self._thread_pool is not None:
+                self.assertTrue(self._thread_pool.was_used())
+
         def test_watch_new_service(self):
             request = health_pb2.HealthCheckRequest(service=_WATCH_SERVICE)
             response_queue = queue.Queue()
@@ -199,9 +206,9 @@ class BaseWatchTests(object):
 class HealthServicerTest(BaseWatchTests.WatchTests):
 
     def setUp(self):
+        self._thread_pool = _thread_pool.RecordingThreadPool(max_workers=None)
         super(HealthServicerTest, self).start_server(
-            health.HealthServicer(
-                experimental_non_blocking=False, experimental_thread_pool=None))
+            non_blocking=True, thread_pool=self._thread_pool)
 
     def test_check_empty_service(self):
         request = health_pb2.HealthCheckRequest()
@@ -239,8 +246,7 @@ class HealthServicerBackwardsCompatibleWatchTest(BaseWatchTests.WatchTests):
 
     def setUp(self):
         super(HealthServicerBackwardsCompatibleWatchTest, self).start_server(
-            health.HealthServicer(
-                experimental_non_blocking=False, experimental_thread_pool=None))
+            non_blocking=False, thread_pool=None)
 
 
 if __name__ == '__main__':