diff --git a/akka-docs-dev/rst/scala/code/docs/http/HttpServerExampleSpec.scala b/akka-docs-dev/rst/scala/code/docs/http/HttpServerExampleSpec.scala
index 5a6a37e1a0..2d4b678689 100644
--- a/akka-docs-dev/rst/scala/code/docs/http/HttpServerExampleSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/http/HttpServerExampleSpec.scala
@@ -22,7 +22,7 @@ class HttpServerExampleSpec
     implicit val materializer = FlowMaterializer()
 
     val serverBinding = Http(system).bind(interface = "localhost", port = 8080)
-    serverBinding.connections.foreach { connection => // foreach materializes the source
+    serverBinding.connections.runForeach { connection => // foreach materializes the source
       println("Accepted new connection from " + connection.remoteAddress)
     }
     //#bind-example
@@ -52,7 +52,7 @@ class HttpServerExampleSpec
       case _: HttpRequest                                => HttpResponse(404, entity = "Unknown resource!")
     }
 
-    serverBinding.connections foreach { connection =>
+    serverBinding.connections runForeach { connection =>
       println("Accepted new connection from " + connection.remoteAddress)
 
       connection handleWithSyncHandler requestHandler
diff --git a/akka-docs-dev/rst/scala/code/docs/stream/IntegrationDocSpec.scala b/akka-docs-dev/rst/scala/code/docs/stream/IntegrationDocSpec.scala
index f5a602f57e..361be23ddb 100644
--- a/akka-docs-dev/rst/scala/code/docs/stream/IntegrationDocSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/stream/IntegrationDocSpec.scala
@@ -307,7 +307,7 @@ class IntegrationDocSpec extends AkkaSpec(IntegrationDocSpec.config) {
     Source(List("a", "B", "C", "D", "e", "F", "g", "H", "i", "J"))
       .map(elem => { println(s"before: $elem"); elem })
       .mapAsync(service.convert)
-      .foreach(elem => println(s"after: $elem"))
+      .runForeach(elem => println(s"after: $elem"))
     //#sometimes-slow-mapAsync
 
     probe.expectMsg("after: A")
@@ -339,7 +339,7 @@ class IntegrationDocSpec extends AkkaSpec(IntegrationDocSpec.config) {
     Source(List("a", "B", "C", "D", "e", "F", "g", "H", "i", "J"))
       .map(elem => { println(s"before: $elem"); elem })
       .mapAsyncUnordered(service.convert)
-      .foreach(elem => println(s"after: $elem"))
+      .runForeach(elem => println(s"after: $elem"))
     //#sometimes-slow-mapAsyncUnordered
 
     probe.receiveN(10).toSet should be(Set(
diff --git a/akka-docs-dev/rst/scala/code/docs/stream/StreamTcpDocSpec.scala b/akka-docs-dev/rst/scala/code/docs/stream/StreamTcpDocSpec.scala
index dea4949424..f51739c8f9 100644
--- a/akka-docs-dev/rst/scala/code/docs/stream/StreamTcpDocSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/stream/StreamTcpDocSpec.scala
@@ -40,7 +40,7 @@ class StreamTcpDocSpec extends AkkaSpec {
     //#echo-server-simple-handle
     val connections: Source[IncomingConnection] = binding.connections
 
-    connections foreach { connection =>
+    connections runForeach { connection =>
       println(s"New connection from: ${connection.remoteAddress}")
 
       val echo = Flow[ByteString]
@@ -77,7 +77,7 @@ class StreamTcpDocSpec extends AkkaSpec {
     val binding = StreamTcp().bind(localhost)
 
     //#welcome-banner-chat-server
-    binding.connections foreach { connection =>
+    binding.connections runForeach { connection =>
 
       val serverLogic = Flow() { implicit b =>
         import FlowGraphImplicits._
diff --git a/akka-docs-dev/rst/scala/code/docs/stream/TwitterStreamQuickstartDocSpec.scala b/akka-docs-dev/rst/scala/code/docs/stream/TwitterStreamQuickstartDocSpec.scala
index 1e8f346c61..827abde491 100644
--- a/akka-docs-dev/rst/scala/code/docs/stream/TwitterStreamQuickstartDocSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/stream/TwitterStreamQuickstartDocSpec.scala
@@ -92,7 +92,7 @@ class TwitterStreamQuickstartDocSpec extends AkkaSpec {
     //#authors-foreachsink-println
 
     //#authors-foreach-println
-    authors.foreach(println)
+    authors.runForeach(println)
     //#authors-foreach-println
   }
 
@@ -149,7 +149,7 @@ class TwitterStreamQuickstartDocSpec extends AkkaSpec {
       val completion: Future[Unit] =
         Source(1 to 10)
           .map(i => { println(s"map => $i"); i })
-          .foreach { i => readLine(s"Element = $i; continue reading? [press enter]\n") }
+          .runForeach { i => readLine(s"Element = $i; continue reading? [press enter]\n") }
 
       Await.ready(completion, 1.minute)
       //#backpressure-by-readline
diff --git a/akka-docs-dev/rst/scala/code/docs/stream/cookbook/RecipeReduceByKey.scala b/akka-docs-dev/rst/scala/code/docs/stream/cookbook/RecipeReduceByKey.scala
index 671c5c7625..30f654b6c7 100644
--- a/akka-docs-dev/rst/scala/code/docs/stream/cookbook/RecipeReduceByKey.scala
+++ b/akka-docs-dev/rst/scala/code/docs/stream/cookbook/RecipeReduceByKey.scala
@@ -23,7 +23,7 @@ class RecipeReduceByKey extends RecipeSpec {
       // add counting logic to the streams
       val countedWords: Source[Future[(String, Int)]] = wordStreams.map {
         case (word, wordStream) =>
-          wordStream.fold((word, 0)) {
+          wordStream.runFold((word, 0)) {
             case ((w, count), _) => (w, count + 1)
           }
       }
@@ -57,7 +57,7 @@ class RecipeReduceByKey extends RecipeSpec {
         val groupStreams = Flow[In].groupBy(groupKey)
         val reducedValues = groupStreams.map {
           case (key, groupStream) =>
-            groupStream.fold((key, foldZero(key))) {
+            groupStream.runFold((key, foldZero(key))) {
               case ((key, aggregated), elem) => (key, fold(aggregated, elem))
             }
         }
diff --git a/akka-docs-dev/rst/scala/stream-flows-and-basics.rst b/akka-docs-dev/rst/scala/stream-flows-and-basics.rst
index 9f3d10f81a..c32b402d45 100644
--- a/akka-docs-dev/rst/scala/stream-flows-and-basics.rst
+++ b/akka-docs-dev/rst/scala/stream-flows-and-basics.rst
@@ -185,7 +185,7 @@ but is not restricted to that - it could also mean opening files or socket conne
 
 Materialization is triggered at so called "terminal operations". Most notably this includes the various forms of the ``run()``
 and ``runWith()`` methods defined on flow elements as well as a small number of special syntactic sugars for running with
-well-known sinks, such as ``foreach(el => )`` (being an alias to ``runWith(Sink.foreach(el => ))``.
+well-known sinks, such as ``runForeach(el => )`` (being an alias to ``runWith(Sink.foreach(el => ))``.
 
 Materialization is currently performed synchronously on the materializing thread.
 Tha actual stream processing is handled by :ref:`Actors actor-scala` started up during the streams materialization,
diff --git a/akka-http-core/src/main/scala/akka/http/model/Multipart.scala b/akka-http-core/src/main/scala/akka/http/model/Multipart.scala
index 84d0641915..38451b72a2 100644
--- a/akka-http-core/src/main/scala/akka/http/model/Multipart.scala
+++ b/akka-http-core/src/main/scala/akka/http/model/Multipart.scala
@@ -58,7 +58,7 @@ object Multipart {
 
   private def strictify[BP <: Multipart.BodyPart, BPS <: Multipart.BodyPart.Strict](parts: Source[BP])(f: BP ⇒ Future[BPS])(implicit ec: ExecutionContext, fm: FlowMaterializer): Future[Vector[BPS]] =
     // TODO: move to Vector `:+` when https://issues.scala-lang.org/browse/SI-8930 is fixed
-    parts.fold(new VectorBuilder[Future[BPS]]) {
+    parts.runFold(new VectorBuilder[Future[BPS]]) {
       case (builder, part) ⇒ builder += f(part)
     }.fast.flatMap(builder ⇒ FastFuture.sequence(builder.result()))
 
diff --git a/akka-http-core/src/main/scala/akka/http/util/StreamUtils.scala b/akka-http-core/src/main/scala/akka/http/util/StreamUtils.scala
index c3c9b8e4cb..9f960e59f3 100644
--- a/akka-http-core/src/main/scala/akka/http/util/StreamUtils.scala
+++ b/akka-http-core/src/main/scala/akka/http/util/StreamUtils.scala
@@ -270,7 +270,7 @@ private[http] object StreamUtils {
  */
 private[http] class EnhancedByteStringSource(val byteStringStream: Source[ByteString]) extends AnyVal {
   def join(implicit materializer: FlowMaterializer): Future[ByteString] =
-    byteStringStream.fold(ByteString.empty)(_ ++ _)
+    byteStringStream.runFold(ByteString.empty)(_ ++ _)
   def utf8String(implicit materializer: FlowMaterializer, ec: ExecutionContext): Future[String] =
     join.map(_.utf8String)
 }
diff --git a/akka-http/src/main/scala/akka/http/unmarshalling/PredefinedFromEntityUnmarshallers.scala b/akka-http/src/main/scala/akka/http/unmarshalling/PredefinedFromEntityUnmarshallers.scala
index fed5fcbd1a..2ad0124efe 100644
--- a/akka-http/src/main/scala/akka/http/unmarshalling/PredefinedFromEntityUnmarshallers.scala
+++ b/akka-http/src/main/scala/akka/http/unmarshalling/PredefinedFromEntityUnmarshallers.scala
@@ -15,7 +15,7 @@ trait PredefinedFromEntityUnmarshallers extends MultipartUnmarshallers {
   implicit def byteStringUnmarshaller(implicit fm: FlowMaterializer): FromEntityUnmarshaller[ByteString] =
     Unmarshaller {
       case HttpEntity.Strict(_, data) ⇒ FastFuture.successful(data)
-      case entity                     ⇒ entity.dataBytes.fold(ByteString.empty)(_ ++ _)
+      case entity                     ⇒ entity.dataBytes.runFold(ByteString.empty)(_ ++ _)
     }
 
   implicit def byteArrayUnmarshaller(implicit fm: FlowMaterializer,
diff --git a/akka-stream-tests/src/test/java/akka/stream/actor/ActorPublisherTest.java b/akka-stream-tests/src/test/java/akka/stream/actor/ActorPublisherTest.java
index 9682d539b9..df4e100f54 100644
--- a/akka-stream-tests/src/test/java/akka/stream/actor/ActorPublisherTest.java
+++ b/akka-stream-tests/src/test/java/akka/stream/actor/ActorPublisherTest.java
@@ -43,8 +43,9 @@ public class ActorPublisherTest extends StreamTest {
       .actorOf(Props.create(TestPublisher.class).withDispatcher("akka.test.stream-dispatcher"));
     final Publisher<Integer> publisher = UntypedActorPublisher.create(ref);
     Source.from(publisher)
-      .foreach(new akka.stream.javadsl.japi.Procedure<Integer>(){
-        @Override public void apply(Integer elem) throws Exception {
+      .runForeach(new akka.stream.javadsl.japi.Procedure<Integer>() {
+        @Override
+        public void apply(Integer elem) throws Exception {
           probe.getRef().tell(elem, ActorRef.noSender());
         }
       }, materializer);
diff --git a/akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java b/akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java
index 3659f82762..b63c53ea3c 100644
--- a/akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java
+++ b/akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java
@@ -65,7 +65,7 @@ public class FlowTest extends StreamTest {
           }
         });
 
-    ints.via(flow1.via(flow2)).fold("", new Function2<String, String, String>() {
+    ints.via(flow1.via(flow2)).runFold("", new Function2<String, String, String>() {
           public String apply(String acc, String elem) {
             return acc + elem;
           }
@@ -116,7 +116,7 @@ public class FlowTest extends StreamTest {
         };
       }
     });
-    Source.from(input).via(flow).foreach(new Procedure<Integer>() {
+    Source.from(input).via(flow).runForeach(new Procedure<Integer>() {
       public void apply(Integer elem) {
         probe.getRef().tell(elem, ActorRef.noSender());
       }
@@ -142,10 +142,10 @@ public class FlowTest extends StreamTest {
         return elem.substring(0, 1);
       }
     });
-    Source.from(input).via(slsFlow).foreach(new Procedure<Pair<String, Source<String>>>() {
+    Source.from(input).via(slsFlow).runForeach(new Procedure<Pair<String, Source<String>>>() {
       @Override
       public void apply(final Pair<String, Source<String>> pair) throws Exception {
-        pair.second().foreach(new Procedure<String>() {
+        pair.second().runForeach(new Procedure<String>() {
           @Override
           public void apply(String elem) throws Exception {
             probe.getRef().tell(new Pair<String, String>(pair.first(), elem), ActorRef.noSender());
@@ -179,7 +179,7 @@ public class FlowTest extends StreamTest {
         return elem.equals(".");
       }
     });
-    Source.from(input).via(flow).foreach(new Procedure<Source<String>>() {
+    Source.from(input).via(flow).runForeach(new Procedure<Source<String>>() {
       @Override
       public void apply(Source<String> subStream) throws Exception {
         subStream.filter(new Predicate<String>() {
@@ -187,7 +187,7 @@ public class FlowTest extends StreamTest {
           public boolean test(String elem) {
             return !elem.equals(".");
           }
-        }).grouped(10).foreach(new Procedure<List<String>>() {
+        }).grouped(10).runForeach(new Procedure<List<String>>() {
           @Override
           public void apply(List<String> chunk) throws Exception {
             probe.getRef().tell(chunk, ActorRef.noSender());
@@ -342,7 +342,7 @@ public class FlowTest extends StreamTest {
     final Source<String> in1 = Source.from(input1);
     final Source<String> in2 = Source.from(input2);
     final Flow<String, String> flow = Flow.of(String.class);
-    in1.via(flow.concat(in2)).foreach(new Procedure<String>() {
+    in1.via(flow.concat(in2)).runForeach(new Procedure<String>() {
       public void apply(String elem) {
         probe.getRef().tell(elem, ActorRef.noSender());
       }
@@ -413,7 +413,7 @@ public class FlowTest extends StreamTest {
         return aggr + in;
       }
     });
-    Future <String> future = Source.from(input).via(flow).fold("", new Function2<String, String, String>() {
+    Future <String> future = Source.from(input).via(flow).runFold("", new Function2<String, String, String>() {
       @Override
       public String apply(String aggr, String in) throws Exception {
         return aggr + in;
@@ -454,7 +454,7 @@ public class FlowTest extends StreamTest {
         return Futures.successful(elem.toUpperCase());
       }
     });
-    Source.from(input).via(flow).foreach(new Procedure<String>() {
+    Source.from(input).via(flow).runForeach(new Procedure<String>() {
       public void apply(String elem) {
         probe.getRef().tell(elem, ActorRef.noSender());
       }
diff --git a/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java b/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
index c8677119ef..4f24a6d366 100644
--- a/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
+++ b/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
@@ -63,7 +63,7 @@ public class SourceTest extends StreamTest {
         public java.util.List<String> apply(java.util.List<String> elem) {
           return elem;
         }
-      }).fold("", new Function2<String, String, String>() {
+      }).runFold("", new Function2<String, String, String>() {
       public String apply(String acc, String elem) {
         return acc + elem;
       }
@@ -82,7 +82,7 @@ public class SourceTest extends StreamTest {
     final java.lang.Iterable<String> input = Arrays.asList("a", "b", "c");
     Source<String> ints = Source.from(input);
 
-    Future<BoxedUnit> completion = ints.foreach(new Procedure<String>() {
+    Future<BoxedUnit> completion = ints.runForeach(new Procedure<String>() {
       public void apply(String elem) {
         probe.getRef().tell(elem, ActorRef.noSender());
       }
@@ -137,7 +137,7 @@ public class SourceTest extends StreamTest {
 
         };
       }
-    }).foreach(new Procedure<Integer>() {
+    }).runForeach(new Procedure<Integer>() {
       public void apply(Integer elem) {
         probe.getRef().tell(elem, ActorRef.noSender());
       }
@@ -162,10 +162,10 @@ public class SourceTest extends StreamTest {
       public String apply(String elem) {
         return elem.substring(0, 1);
       }
-    }).foreach(new Procedure<Pair<String, Source<String>>>() {
+    }).runForeach(new Procedure<Pair<String, Source<String>>>() {
       @Override
       public void apply(final Pair<String, Source<String>> pair) throws Exception {
-        pair.second().foreach(new Procedure<String>() {
+        pair.second().runForeach(new Procedure<String>() {
           @Override
           public void apply(String elem) throws Exception {
             probe.getRef().tell(new Pair<String, String>(pair.first(), elem), ActorRef.noSender());
@@ -198,7 +198,7 @@ public class SourceTest extends StreamTest {
       public boolean test(String elem) {
         return elem.equals(".");
       }
-    }).foreach(new Procedure<Source<String>>() {
+    }).runForeach(new Procedure<Source<String>>() {
       @Override
       public void apply(Source<String> subStream) throws Exception {
         subStream.filter(new Predicate<String>() {
@@ -206,7 +206,7 @@ public class SourceTest extends StreamTest {
           public boolean test(String elem) {
             return !elem.equals(".");
           }
-        }).grouped(10).foreach(new Procedure<List<String>>() {
+        }).grouped(10).runForeach(new Procedure<List<String>>() {
           @Override
           public void apply(List<String> chunk) throws Exception {
             probe.getRef().tell(chunk, ActorRef.noSender());
@@ -240,7 +240,7 @@ public class SourceTest extends StreamTest {
     final Source<String> in1 = Source.from(input1);
     final Source<String> in2 = Source.from(input2);
 
-    in1.concat(in2).foreach(new Procedure<String>() {
+    in1.concat(in2).runForeach(new Procedure<String>() {
       public void apply(String elem) {
         probe.getRef().tell(elem, ActorRef.noSender());
       }
@@ -260,7 +260,7 @@ public class SourceTest extends StreamTest {
         return input1.iterator();
       }
     };
-    Source.from(input).foreach(new Procedure<Integer>() {
+    Source.from(input).runForeach(new Procedure<Integer>() {
       public void apply(Integer elem) {
         probe.getRef().tell(elem, ActorRef.noSender());
       }
@@ -375,7 +375,7 @@ public class SourceTest extends StreamTest {
       public String apply(String aggr, String in) throws Exception {
         return aggr + in;
       }
-    }).fold("", new Function2<String, String, String>() {
+    }).runFold("", new Function2<String, String, String>() {
       @Override
       public String apply(String aggr, String in) throws Exception {
         return aggr + in;
@@ -431,7 +431,7 @@ public class SourceTest extends StreamTest {
       public Future<String> apply(String elem) {
         return Futures.successful(elem.toUpperCase());
       }
-    }).foreach(new Procedure<String>() {
+    }).runForeach(new Procedure<String>() {
       public void apply(String elem) {
         probe.getRef().tell(elem, ActorRef.noSender());
       }
diff --git a/akka-stream-tests/src/test/java/akka/stream/javadsl/StreamTcpTest.java b/akka-stream-tests/src/test/java/akka/stream/javadsl/StreamTcpTest.java
index f2932186b5..292a04f14c 100644
--- a/akka-stream-tests/src/test/java/akka/stream/javadsl/StreamTcpTest.java
+++ b/akka-stream-tests/src/test/java/akka/stream/javadsl/StreamTcpTest.java
@@ -63,7 +63,7 @@ public class StreamTcpTest extends StreamTest {
     final Source<ByteString> responseStream =
       Source.from(testInput).via(StreamTcp.get(system).outgoingConnection(serverAddress).flow());
     
-    final Future<ByteString> resultFuture = responseStream.fold(
+    final Future<ByteString> resultFuture = responseStream.runFold(
         ByteString.empty(), new Function2<ByteString, ByteString, ByteString>() {
           public ByteString apply(ByteString acc, ByteString elem) {
             return acc.concat(elem);
diff --git a/akka-stream-tests/src/test/scala/akka/stream/io/StreamTcpSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/io/StreamTcpSpec.scala
index 6bffa63ad5..42b5b56ecd 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/io/StreamTcpSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/io/StreamTcpSpec.scala
@@ -56,7 +56,7 @@ class StreamTcpSpec extends AkkaSpec with TcpHelper {
       val resultFuture =
         Source(idle.publisherProbe)
           .via(StreamTcp().outgoingConnection(server.address).flow)
-          .fold(ByteString.empty)((acc, in) ⇒ acc ++ in)
+          .runFold(ByteString.empty)((acc, in) ⇒ acc ++ in)
       val serverConnection = server.waitAccept()
 
       for (in ← testInput) {
@@ -198,7 +198,7 @@ class StreamTcpSpec extends AkkaSpec with TcpHelper {
       val testInput = (0 to 255).map(ByteString(_))
       val expectedOutput = ByteString(Array.tabulate(256)(_.asInstanceOf[Byte]))
       val resultFuture =
-        Source(testInput).via(StreamTcp().outgoingConnection(serverAddress).flow).fold(ByteString.empty)((acc, in) ⇒ acc ++ in)
+        Source(testInput).via(StreamTcp().outgoingConnection(serverAddress).flow).runFold(ByteString.empty)((acc, in) ⇒ acc ++ in)
 
       Await.result(resultFuture, 3.seconds) should be(expectedOutput)
       Await.result(binding.unbind(echoServerMM), 3.seconds)
@@ -226,7 +226,7 @@ class StreamTcpSpec extends AkkaSpec with TcpHelper {
           .via(echoConnection)
           .via(echoConnection)
           .via(echoConnection)
-          .fold(ByteString.empty)((acc, in) ⇒ acc ++ in)
+          .runFold(ByteString.empty)((acc, in) ⇒ acc ++ in)
 
       Await.result(resultFuture, 5.seconds) should be(expectedOutput)
       Await.result(binding.unbind(echoServerMM), 3.seconds)
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConflateSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConflateSpec.scala
index 484be8ab1f..16c131ed69 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConflateSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConflateSpec.scala
@@ -58,7 +58,7 @@ class FlowConflateSpec extends AkkaSpec {
       val future = Source(1 to 1000)
         .conflate(seed = i ⇒ i)(aggregate = (sum, i) ⇒ sum + i)
         .map { i ⇒ if (ThreadLocalRandom.current().nextBoolean()) Thread.sleep(10); i }
-        .fold(0)(_ + _)
+        .runFold(0)(_ + _)
       Await.result(future, 10.seconds) should be(500500)
     }
 
@@ -95,7 +95,7 @@ class FlowConflateSpec extends AkkaSpec {
       val future = Source(1 to 50)
         .conflate(seed = i ⇒ i)(aggregate = (sum, i) ⇒ sum + i)
         .buffer(50, OverflowStrategy.backpressure)
-        .fold(0)(_ + _)
+        .runFold(0)(_ + _)
       Await.result(future, 3.seconds) should be((1 to 50).sum)
     }
 
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowExpandSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowExpandSpec.scala
index fb7dde14e9..bae944dd8c 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowExpandSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowExpandSpec.scala
@@ -91,7 +91,7 @@ class FlowExpandSpec extends AkkaSpec {
       val future = Source(1 to 100)
         .map { i ⇒ if (ThreadLocalRandom.current().nextBoolean()) Thread.sleep(10); i }
         .expand(seed = i ⇒ i)(extrapolate = i ⇒ (i, i))
-        .fold(Set.empty[Int])(_ + _)
+        .runFold(Set.empty[Int])(_ + _)
 
       Await.result(future, 10.seconds) should contain theSameElementsAs ((1 to 100).toSet)
     }
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowFoldSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowFoldSpec.scala
index f4699229a3..3054a249ce 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowFoldSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowFoldSpec.scala
@@ -17,14 +17,14 @@ class FlowFoldSpec extends AkkaSpec with DefaultTimeout {
 
     "fold" in {
       val input = 1 to 100
-      val future = Source(input).fold(0)(_ + _)
+      val future = Source(input).runFold(0)(_ + _)
       val expected = input.fold(0)(_ + _)
       Await.result(future, timeout.duration) should be(expected)
     }
 
     "propagate an error" in {
       val error = new Exception with NoStackTrace
-      val future = Source[Unit](() ⇒ throw error).fold(())((_, _) ⇒ ())
+      val future = Source[Unit](() ⇒ throw error).runFold(())((_, _) ⇒ ())
       the[Exception] thrownBy Await.result(future, timeout.duration) should be(error)
     }
 
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowForeachSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowForeachSpec.scala
index 35654b5198..e92ff3fcc6 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowForeachSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowForeachSpec.scala
@@ -16,7 +16,7 @@ class FlowForeachSpec extends AkkaSpec {
   "A Foreach" must {
 
     "call the procedure for each element" in {
-      Source(1 to 3).foreach(testActor ! _) onSuccess {
+      Source(1 to 3).runForeach(testActor ! _) onSuccess {
         case _ ⇒ testActor ! "done"
       }
       expectMsg(1)
@@ -26,7 +26,7 @@ class FlowForeachSpec extends AkkaSpec {
     }
 
     "complete the future for an empty stream" in {
-      Source.empty.foreach(testActor ! _) onSuccess {
+      Source.empty.runForeach(testActor ! _) onSuccess {
         case _ ⇒ testActor ! "done"
       }
       expectMsg("done")
@@ -34,7 +34,7 @@ class FlowForeachSpec extends AkkaSpec {
 
     "yield the first error" in {
       val p = StreamTestKit.PublisherProbe[Int]()
-      Source(p).foreach(testActor ! _) onFailure {
+      Source(p).runForeach(testActor ! _) onFailure {
         case ex ⇒ testActor ! ex
       }
       val proc = p.expectSubscription
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowScanSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowScanSpec.scala
index 0429c61efc..6050b23025 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowScanSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowScanSpec.scala
@@ -23,7 +23,7 @@ class FlowScanSpec extends AkkaSpec {
   "A Scan" must {
 
     def scan(s: Source[Int], duration: Duration = 5.seconds): immutable.Seq[Int] =
-      Await.result(s.scan(0)(_ + _).fold(immutable.Seq.empty[Int])(_ :+ _), duration)
+      Await.result(s.scan(0)(_ + _).runFold(immutable.Seq.empty[Int])(_ :+ _), duration)
 
     "Scan" in {
       val v = Vector.fill(random.nextInt(100, 1000))(random.nextInt())
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/ImplicitFlowMaterializerSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/ImplicitFlowMaterializerSpec.scala
index 504c8b790d..2cb0adae1f 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/ImplicitFlowMaterializerSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/ImplicitFlowMaterializerSpec.scala
@@ -21,7 +21,7 @@ object ImplicitFlowMaterializerSpec {
       case "run" ⇒
         // run takes an implicit FlowMaterializer parameter, which is provided by ImplicitFlowMaterializer
         import context.dispatcher
-        flow.fold("")(_ + _) pipeTo sender()
+        flow.runFold("")(_ + _) pipeTo sender()
     }
   }
 }
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/OptimizingActorBasedFlowMaterializerSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/OptimizingActorBasedFlowMaterializerSpec.scala
index 12660a6343..6068654501 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/OptimizingActorBasedFlowMaterializerSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/OptimizingActorBasedFlowMaterializerSpec.scala
@@ -28,7 +28,7 @@ class OptimizingActorBasedFlowMaterializerSpec extends AkkaSpec with ImplicitSen
         take(20).
         take(10).
         drop(5).
-        fold(0)(_ + _)
+        runFold(0)(_ + _)
 
       val expected = (1 to 100).
         drop(9).
@@ -44,7 +44,7 @@ class OptimizingActorBasedFlowMaterializerSpec extends AkkaSpec with ImplicitSen
     "optimize map + map" in {
       implicit val mat = FlowMaterializer().asInstanceOf[ActorBasedFlowMaterializer].copy(optimizations = Optimizations.all)
 
-      val fl = Source(1 to 100).map(_ + 2).map(_ * 2).fold(0)(_ + _)
+      val fl = Source(1 to 100).map(_ + 2).map(_ * 2).runFold(0)(_ + _)
       val expected = (1 to 100).map(_ + 2).map(_ * 2).fold(0)(_ + _)
 
       Await.result(fl, 5.seconds) should be(expected)
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/PublisherSinkSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/PublisherSinkSpec.scala
index 957848316e..f954d6dec6 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/PublisherSinkSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/PublisherSinkSpec.scala
@@ -29,7 +29,7 @@ class PublisherSinkSpec extends AkkaSpec {
       }.run()
 
       Seq(p1, p2) map { sink ⇒
-        Source(m.get(sink)).map(identity).fold(0)(_ + _)
+        Source(m.get(sink)).map(identity).runFold(0)(_ + _)
       } zip Seq(30, 15) foreach {
         case (future, result) ⇒ whenReady(future)(_ shouldBe result)
       }
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
index 2171909475..4176956e64 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
@@ -205,7 +205,7 @@ class Source[+Out](delegate: scaladsl.Source[Out]) {
    * function evaluation when the input stream ends, or completed with `Failure`
    * if there is an error is signaled in the stream.
    */
-  def fold[U](zero: U, f: japi.Function2[U, Out, U], materializer: FlowMaterializer): Future[U] =
+  def runFold[U](zero: U, f: japi.Function2[U, Out, U], materializer: FlowMaterializer): Future[U] =
     runWith(Sink.fold(zero, f), materializer)
 
   /**
@@ -223,7 +223,7 @@ class Source[+Out](delegate: scaladsl.Source[Out]) {
    * normal end of the stream, or completed with `Failure` if there is an error is signaled in
    * the stream.
    */
-  def foreach(f: japi.Procedure[Out], materializer: FlowMaterializer): Future[Unit] =
+  def runForeach(f: japi.Procedure[Out], materializer: FlowMaterializer): Future[Unit] =
     runWith(Sink.foreach(f), materializer)
 
   // COMMON OPS //
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala
index 39ea49e74a..99112e3518 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala
@@ -45,7 +45,7 @@ trait Source[+Out] extends FlowOps[Out] with Materializable {
    * function evaluation when the input stream ends, or completed with `Failure`
    * if there is an error is signaled in the stream.
    */
-  def fold[U](zero: U)(f: (U, Out) ⇒ U)(implicit materializer: FlowMaterializer): Future[U] = runWith(FoldSink(zero)(f)) // FIXME why is fold always an end step?
+  def runFold[U](zero: U)(f: (U, Out) ⇒ U)(implicit materializer: FlowMaterializer): Future[U] = runWith(FoldSink(zero)(f)) // FIXME why is fold always an end step?
 
   /**
    * Shortcut for running this `Source` with a foreach procedure. The given procedure is invoked
@@ -54,7 +54,7 @@ trait Source[+Out] extends FlowOps[Out] with Materializable {
    * normal end of the stream, or completed with `Failure` if there is an error is signaled in
    * the stream.
    */
-  def foreach(f: Out ⇒ Unit)(implicit materializer: FlowMaterializer): Future[Unit] = runWith(ForeachSink(f))
+  def runForeach(f: Out ⇒ Unit)(implicit materializer: FlowMaterializer): Future[Unit] = runWith(ForeachSink(f))
 
   /**
    * Concatenates a second source so that the first element