diff --git a/backend/documents_parser/tests/test_end_to_end.py b/backend/documents_parser/tests/test_end_to_end.py
index 5d0bc31d..b994cd11 100644
--- a/backend/documents_parser/tests/test_end_to_end.py
+++ b/backend/documents_parser/tests/test_end_to_end.py
@@ -267,3 +267,6 @@ class TestPdfToEpcPropertyDataFixture2:
 
     def test_cylinder_insulation_thickness(self, result: EpcPropertyData) -> None:
         assert result.sap_heating.cylinder_insulation_thickness_mm == 38
+
+    def test_cylinder_size(self, result: EpcPropertyData) -> None:
+        assert result.sap_heating.cylinder_size == "Normal (90-130 litres)"
diff --git a/backend/documents_parser/tests/test_extractor.py b/backend/documents_parser/tests/test_extractor.py
index 6eda5284..27214fd2 100644
--- a/backend/documents_parser/tests/test_extractor.py
+++ b/backend/documents_parser/tests/test_extractor.py
@@ -398,6 +398,9 @@ class TestWaterHeatingCylinderThickness:
     def test_cylinder_insulation_thickness_mm_absent(self, hhw_no_cylinder: HeatingAndHotWater) -> None:
         assert hhw_no_cylinder.water_heating.insulation_thickness_mm is None
 
+    def test_cylinder_size(self, hhw: HeatingAndHotWater) -> None:
+        assert hhw.water_heating.cylinder_size == "Normal (90-130 litres)"
+
 
 class TestHeatingAndHotWater:
     @pytest.fixture
diff --git a/datatypes/epc/domain/epc_property_data.py b/datatypes/epc/domain/epc_property_data.py
index cc21d7f9..f0d8607d 100644
--- a/datatypes/epc/domain/epc_property_data.py
+++ b/datatypes/epc/domain/epc_property_data.py
@@ -54,8 +54,8 @@ class SapHeating:
     instantaneous_wwhrs: InstantaneousWwhrs
     main_heating_details: List[MainHeatingDetail]
     has_fixed_air_conditioning: bool
-    cylinder_size: Optional[int] = (
-        None  # int code from API; not directly available from site notes
+    cylinder_size: Optional[Union[int, str]] = (
+        None  # int code from API; str (e.g. "Normal (90-130 litres)") from site notes
     )
     water_heating_code: Optional[int] = None  # TODO: make enum?
     water_heating_fuel: Optional[int] = None  # TODO: make enum?