diff --git a/Makefile b/Makefile
index aa2682ee5f..00c1fb21f4 100644
--- a/Makefile
+++ b/Makefile
@@ -61,7 +61,7 @@ clean:
 clean-import: clean import
 	@echo "✓ Clean import complete!"
 
-test: setup
+test: setup fetch-schemas
 	@echo "Running unit tests..."
 	@$(PYTHON) -m unittest discover tests -v
 
diff --git a/data/wash-media/generic/water.yaml b/data/wash-media/generic/water.yaml
new file mode 100644
index 0000000000..9450b0176e
--- /dev/null
+++ b/data/wash-media/generic/water.yaml
@@ -0,0 +1,7 @@
+slug: water
+uuid: 78c9e93b-94dc-4c63-af42-4bce6304142f
+brand:
+  slug: generic
+name: Water
+density: 1
+wash_capacity: 10000
diff --git a/schema_version.conf b/schema_version.conf
index a8b7cf3f2c..e6ba1798a4 100644
--- a/schema_version.conf
+++ b/schema_version.conf
@@ -1,5 +1,5 @@
 # OpenPrintTag Schema Configuration
 SCHEMA_REPO_URL="https://github.com/OpenPrintTag/openprinttag-architecture.git"
-SCHEMA_COMMIT="438a81fb5ae1c3c21a1c23ba00c309db0a337da0"
+SCHEMA_COMMIT="328e859465f9a3c499e69f141a7bc3c16273e911"
 SCHEMA_SPARSE_PATH="schema/generated/opt_db_schema"
 SCHEMA_TARGET_DIR="./openprinttag"
diff --git a/scripts/validate_json_schema.py b/scripts/validate_json_schema.py
index 84ef3b013e..355c140b1c 100755
--- a/scripts/validate_json_schema.py
+++ b/scripts/validate_json_schema.py
@@ -46,6 +46,7 @@ class JsonSchemaValidator:
         'materials': 'material.schema.json',
         'material-packages': 'material_package.schema.json',
         'material-containers': 'material_container.schema.json',
+        'wash-media': 'wash_medium.schema.json',
     }
 
     # Foreign key definitions: entity -> [(field_path, target_entity, target_field, is_array, condition)]
@@ -68,6 +69,9 @@ class JsonSchemaValidator:
         'brands': [
             (['countries_of_origin'], 'countries', 'code', True, None),
         ],
+        'wash-media': [
+            (['brand', 'slug'], 'brands', 'slug', False, None),
+        ],
     }
 
     def __init__(self, base_path: Path):
diff --git a/tests/test_validate_wash_media.py b/tests/test_validate_wash_media.py
new file mode 100644
index 0000000000..945a9c5c8a
--- /dev/null
+++ b/tests/test_validate_wash_media.py
@@ -0,0 +1,64 @@
+"""
+Tests that wash-media entities are actually validated by validate_json_schema.py.
+"""
+
+import shutil
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent))
+sys.path.insert(0, str(Path(__file__).parent.parent / "scripts"))
+
+from scripts.validate_json_schema import JsonSchemaValidator
+
+REPO_ROOT = Path(__file__).parent.parent
+
+
+class TestWashMediaValidation(unittest.TestCase):
+    """Confirm the wash-media data directory is wired into the validator."""
+
+    def test_generic_water_is_validated_without_errors(self):
+        """The real data/wash-media tree should be picked up and pass validation."""
+        validator = JsonSchemaValidator(REPO_ROOT)
+        count = validator.validate_entity_directory('wash-media', validator.ENTITY_SCHEMA_MAPPING['wash-media'])
+
+        self.assertGreaterEqual(count, 1, "no wash-media files were found/validated")
+        wash_media_errors = [e for e in validator.errors if e.entity == 'wash-media']
+        self.assertEqual(
+            [str(e) for e in wash_media_errors], [],
+            "wash-media data failed schema validation"
+        )
+
+    def test_invalid_wash_medium_is_rejected(self):
+        """A wash medium with a non-numeric density must be caught by the validator."""
+        temp_dir = Path(tempfile.mkdtemp())
+        self.addCleanup(shutil.rmtree, temp_dir, ignore_errors=True)
+
+        wash_media_dir = temp_dir / "wash-media" / "generic"
+        wash_media_dir.mkdir(parents=True)
+        (wash_media_dir / "bad-water.yaml").write_text(
+            "slug: bad-water\n"
+            "uuid: 78c9e93b-94dc-4c63-af42-4bce6304142f\n"
+            "brand:\n"
+            "  slug: generic\n"
+            "name: Bad Water\n"
+            "density: not-a-number\n"
+            "wash_capacity: 10000\n"
+        )
+
+        validator = JsonSchemaValidator(REPO_ROOT)
+        validator.data_dir = temp_dir  # schema_dir stays pointed at the real, current schema
+
+        validator.validate_entity_directory('wash-media', validator.ENTITY_SCHEMA_MAPPING['wash-media'])
+
+        schema_errors = [e for e in validator.errors if e.rule == 'schema_validation']
+        self.assertTrue(
+            schema_errors,
+            "validator did not flag a wash medium with a non-numeric density"
+        )
+
+
+if __name__ == '__main__':
+    unittest.main()