diff --git a/layers/transportation_name/merge_highways.sql b/layers/transportation_name/merge_highways.sql
index 6a58c99..c834c17 100644
--- a/layers/transportation_name/merge_highways.sql
+++ b/layers/transportation_name/merge_highways.sql
@@ -1,3 +1,9 @@
+
+DROP TABLE IF EXISTS osm_transportation_name_linestring CASCADE;
+DROP TABLE IF EXISTS osm_transportation_name_linestring_gen1 CASCADE;
+DROP TABLE IF EXISTS osm_transportation_name_linestring_gen2 CASCADE;
+DROP TABLE IF EXISTS osm_transportation_name_linestring_gen3 CASCADE;
+
 -- Instead of using relations to find out the road names we
 -- stitch together the touching ways with the same name
 -- to allow for nice label rendering
diff --git a/layers/water_name/water_lakeline.sql b/layers/water_name/water_lakeline.sql
index 20381ef..16522e8 100644
--- a/layers/water_name/water_lakeline.sql
+++ b/layers/water_name/water_lakeline.sql
@@ -1,3 +1,6 @@
+
+DROP TABLE IF EXISTS osm_water_lakeline CASCADE;
+
 -- etldoc:  osm_water_polygon ->  osm_water_lakeline
 -- etldoc:  lake_centerline  ->  osm_water_lakeline
 CREATE TABLE IF NOT EXISTS osm_water_lakeline AS (
diff --git a/layers/water_name/water_point.sql b/layers/water_name/water_point.sql
index 5f9658a..498a6e8 100644
--- a/layers/water_name/water_point.sql
+++ b/layers/water_name/water_point.sql
@@ -1,3 +1,6 @@
+
+DROP TABLE IF EXISTS osm_water_point CASCADE;
+
 -- etldoc:  osm_water_polygon ->  osm_water_point
 -- etldoc:  lake_centerline ->  osm_water_point
 CREATE TABLE IF NOT EXISTS osm_water_point AS (
diff --git a/layers/waterway/merge_waterway.sql b/layers/waterway/merge_waterway.sql
index c58b21a..604e004 100644
--- a/layers/waterway/merge_waterway.sql
+++ b/layers/waterway/merge_waterway.sql
@@ -1,3 +1,9 @@
+
+DROP TABLE IF EXISTS osm_important_waterway_linestring CASCADE;
+DROP TABLE IF EXISTS osm_important_waterway_linestring_gen1 CASCADE;
+DROP TABLE IF EXISTS osm_important_waterway_linestring_gen2 CASCADE;
+DROP TABLE IF EXISTS osm_important_waterway_linestring_gen3 CASCADE;
+
 -- We merge the waterways by name like the highways
 -- This helps to drop not important rivers (since they do not have a name)
 -- and also makes it possible to filter out too short rivers