diff --git a/data/gwr-window.ui b/data/gwr-window.ui
index 68f6dee..f9eddca 100644
--- a/data/gwr-window.ui
+++ b/data/gwr-window.ui
@@ -22,6 +22,7 @@
             <property name="visible">True</property>
             <property name="can_focus">True</property>
             <property name="receives_default">True</property>
+            <property name="action_name">win.add</property>
             <child>
               <object class="GtkImage">
                 <property name="visible">True</property>
diff --git a/src/gwr-water-level.c b/src/gwr-water-level.c
index d514e27..58324f9 100644
--- a/src/gwr-water-level.c
+++ b/src/gwr-water-level.c
@@ -32,7 +32,19 @@ void
 gwr_water_level_set_level(GwrWaterLevel *self,
                           gfloat         level)
 {
-    self->level = MAX(0, MIN(level, 1.0));
+    g_debug("Setting level to %.2f", level);
+
+    if (G_UNLIKELY(level > 1.0)) {
+        g_warning("Value (%.2f) is too large.  Scaling down to 1.0", level);
+        level = 1.0;
+    } else if (G_UNLIKELY(level < 0.0)) {
+        g_warning("Value (%.2f) is too small.  Scaling up to 0.0", level);
+        level = 0.0;
+    }
+
+    self->level = level;
+
+    gtk_widget_queue_draw(GTK_WIDGET(self));
 
     g_object_notify_by_pspec(G_OBJECT(self), props[PROP_LEVEL]);
 }
diff --git a/src/gwr-window.c b/src/gwr-window.c
index b45602c..042aae8 100644
--- a/src/gwr-window.c
+++ b/src/gwr-window.c
@@ -31,6 +31,14 @@ struct _GwrWindow
 
 G_DEFINE_TYPE (GwrWindow, gwr_window, GTK_TYPE_APPLICATION_WINDOW)
 
+static void gwr_window_add_action(GSimpleAction *action,
+                                  GVariant      *parameter,
+                                  gpointer       user_data);
+
+static GActionEntry win_entries[] = {
+    { "add", gwr_window_add_action, NULL, NULL, NULL },
+};
+
 static void
 gwr_window_class_init (GwrWindowClass *klass)
 {
@@ -47,4 +55,16 @@ gwr_window_init (GwrWindow *self)
   g_type_ensure(GWR_TYPE_WATER_LEVEL);
 
   gtk_widget_init_template (GTK_WIDGET (self));
+
+    g_action_map_add_action_entries(G_ACTION_MAP(self), win_entries, G_N_ELEMENTS(win_entries), self);
+}
+
+static void
+ gwr_window_add_action(GSimpleAction *action,
+                       GVariant      *parameter,
+                       gpointer       user_data)
+{
+    GwrWindow *self = GWR_WINDOW(user_data);
+
+    gwr_water_level_set_level (self->level, gwr_water_level_get_level (self->level) + 0.1);
 }