diff --git a/containers/backend/Dockerfile b/containers/backend/Dockerfile
index 242746ca..6e9e9ce7 100644
--- a/containers/backend/Dockerfile
+++ b/containers/backend/Dockerfile
@@ -3,10 +3,13 @@ LABEL maintainer="frederick.thomas@ouce.ox.ac.uk"
 
 WORKDIR /code
 
+# Install project with dependencies - these can be cached as docker layers if unchanged
 COPY pyproject.toml .
-
 RUN python -m pip install .
+
+# Copy and install latest package code
 COPY ./backend /code/backend
+RUN python -m pip install --upgrade --compile .
 
 CMD ["uvicorn", "backend.app.main:app", "--host", "0.0.0.0", "--port", "8888"]
 
diff --git a/containers/backend/backend/app/routers/tiles.py b/containers/backend/backend/app/routers/tiles.py
index 53a08cf1..4ff2692e 100644
--- a/containers/backend/backend/app/routers/tiles.py
+++ b/containers/backend/backend/app/routers/tiles.py
@@ -16,6 +16,7 @@
 from sqlalchemy.exc import NoResultFound
 from sqlalchemy.orm import Session
 from geoalchemy2 import functions
+from terracotta.exceptions import DatasetNotFoundError
 
 
 from app import schemas
@@ -93,19 +94,29 @@ def _domain_exists(db: Session, domain: str) -> bool:
     return res == 1
 
 
-def _tile_db_from_domain(db: Session, domain: str) -> str:
+def _tile_db_from_domain(domain: str) -> str:
     """
     Query the name of the mysql database within-which the tiles reside
         using the first value of the path keys (which links to hazard-type in the UI)
         See: frontend/src/config/hazards/domains.ts
     """
-    source_db = db.execute(
-        # Should only return one entry
-        select(models.RasterTileSource.source_db).where(
-            models.RasterTileSource.domain == domain
-        )
-    ).scalar_one()
-    return source_db
+    # TODO try conventional or configured mappin again - hot fix for db pool exhaustion
+    domain_to_db = {
+        "buildings": "terracotta_buildings",
+        "coastal": "terracotta_aqueduct",
+        "cyclone_iris": "terracotta_iris",
+        "cyclone": "terracotta_cyclone",
+        "dem": "terracotta_dem",
+        "drought": "terracotta_drought",
+        "earthquake": "terracotta_gem_earthquake",
+        "extreme_heat": "terracotta_extreme_heat",
+        "fluvial": "terracotta_aqueduct",
+        "land_cover": "terracotta_land_cover",
+        "nature": "terracotta_exposure_nature",
+        "population": "terracotta_jrc_pop",
+        "traveltime_to_healthcare": "terracotta_traveltime_to_healthcare",
+    }
+    return domain_to_db[domain]
 
 
 def _source_options(source_db: str, domain: str = None) -> List[dict]:
@@ -307,7 +318,6 @@ async def get_tile(
     colormap: Union[str, None] = None,
     stretch_range: Union[str, None] = None,
     explicit_color_map: Union[str, None] = None,
-    db: Session = Depends(get_db),
 ):
     """
     Serves XYZ Raster Tiles with the given colormap / stretch range or explicit color map for categorical data.
@@ -346,9 +356,9 @@ async def get_tile(
     parsed_keys = _parse_keys(keys)
     domain = _domain_from_keys(parsed_keys)
     try:
-        source_db = _tile_db_from_domain(db, domain)
+        source_db = _tile_db_from_domain(domain)
         logger.debug("source DB for tile path: %s", source_db)
-    except NoResultFound:
+    except KeyError:
         raise HTTPException(
             status_code=404,
             detail=f"No source database for the given domain {domain} could be found",
@@ -393,6 +403,12 @@ async def get_tile(
             status_code=400,
             detail=f"source database {source_db} does not exist in tiles metastore",
         )
+    except DatasetNotFoundError as err:
+        handle_exception(logger, err)
+        raise HTTPException(
+            status_code=400,
+            detail=f"layer with keys {parsed_keys} not found in {source_db} in tiles metastore",
+        )
     except Exception as err:
         handle_exception(logger, err)
         raise HTTPException(status_code=500)
diff --git a/containers/backend/backend/app/schemas.py b/containers/backend/backend/app/schemas.py
index 9b20a5f6..fcf30b91 100644
--- a/containers/backend/backend/app/schemas.py
+++ b/containers/backend/backend/app/schemas.py
@@ -1,5 +1,5 @@
 from enum import Enum
-from typing import Generic, List, Optional, TypeVar
+from typing import Generic, List, Optional, TypeVar, Union
 from pydantic import BaseModel, ConfigDict, conint, validator
 
 
@@ -7,7 +7,7 @@ class FeatureBase(BaseModel):
     id: int
     string_id: str
     layer: str
-    sublayer: str | None
+    sublayer: Optional[str] = None
     properties: dict
 
 
@@ -33,7 +33,7 @@ class DataParameters(BaseModel):
 class ExpectedDamagesDimensions(DataDimensions):
     hazard: str
     rcp: str
-    epoch: str
+    epoch: Union[str, int]
     protection_standard: int
 
 
@@ -54,7 +54,7 @@ class ExpectedDamage(ExpectedDamagesDimensions, ExpectedDamagesVariables):
 class ReturnPeriodDamagesDimensions(DataDimensions):
     hazard: str
     rcp: str
-    epoch: str
+    epoch: Union[str, int]
     rp: int
 
 
diff --git a/docker-compose-dev.yaml b/docker-compose-dev.yaml
index 12ac664d..b9a6fc88 100644
--- a/docker-compose-dev.yaml
+++ b/docker-compose-dev.yaml
@@ -46,7 +46,7 @@ services:
 
   backend:
     build: ./containers/backend
-    image: ghcr.io/nismod/gri-backend:1.3
+    image: ghcr.io/nismod/gri-backend:1.4.2
     volumes:
       - ./etl/raster/cog/:/data/
       - ./containers/backend/backend/:/code/backend/
diff --git a/docker-compose-prod-build.yaml b/docker-compose-prod-build.yaml
index 3100120a..885a6450 100644
--- a/docker-compose-prod-build.yaml
+++ b/docker-compose-prod-build.yaml
@@ -1,6 +1,6 @@
 services:
   backend:
-    image: ghcr.io/nismod/gri-backend:1.3
+    image: ghcr.io/nismod/gri-backend:1.4.2
     build: ./containers/backend
 
   vector-tileserver:
diff --git a/docker-compose-prod-deploy.yaml b/docker-compose-prod-deploy.yaml
index fab79aab..91bbb3c5 100644
--- a/docker-compose-prod-deploy.yaml
+++ b/docker-compose-prod-deploy.yaml
@@ -45,7 +45,7 @@ services:
     mem_limit: "250M"
 
   backend:
-    image: ghcr.io/nismod/gri-backend:1.3
+    image: ghcr.io/nismod/gri-backend:1.4.2
     restart: always
     volumes:
       - ./tileserver/raster/data:/data