diff --git a/.flake8 b/.flake8
index 21099b7..c2cf6c9 100644
--- a/.flake8
+++ b/.flake8
@@ -14,3 +14,4 @@ extend-ignore =
     D100,
     D104,
     D107,
+    E203,
diff --git a/pyproject.toml b/pyproject.toml
index 5812612..23aa34e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,7 +31,6 @@ pandas = "^2.1.0"
 flake8-broken-line = "^1.0.0"
 loguru = "^0.7.2"
 importlib-metadata = "^7.2.1"
-env_yaml = "^0.0.3"
 
 [tool.poetry.dev-dependencies]
 pyspark = "^3.4.1"
diff --git a/rialto/common/env_yaml.py b/rialto/common/env_yaml.py
new file mode 100644
index 0000000..e92bf67
--- /dev/null
+++ b/rialto/common/env_yaml.py
@@ -0,0 +1,35 @@
+import os
+import re
+
+import yaml
+from loguru import logger
+
+__all__ = ["EnvLoader"]
+
+# Regex pattern to capture variable and the rest of the string
+_path_matcher = re.compile(r"(?P<before>.*)\$\{(?P<env_name>[^}^{:]+)(?::(?P<default_value>[^}^{]*))?\}(?P<after>.*)")
+
+
+def _path_constructor(loader, node):
+    value = node.value
+    match = _path_matcher.search(value)
+    if match:
+        before = match.group("before")
+        after = match.group("after")
+        sub = os.getenv(match.group("env_name"), match.group("default_value"))
+        if sub is None:
+            raise ValueError(f"Environment variable {match.group('env_name')} has no assigned value")
+        new_value = before + sub + after
+        logger.info(f"Config: Replacing {value}, with {new_value}")
+        return new_value
+    return value
+
+
+class EnvLoader(yaml.SafeLoader):
+    """Custom loader that replaces values with environment variables"""
+
+    pass
+
+
+EnvLoader.add_implicit_resolver("!env_substitute", _path_matcher, None)
+EnvLoader.add_constructor("!env_substitute", _path_constructor)
diff --git a/rialto/common/utils.py b/rialto/common/utils.py
index b2e19b4..6f5ed1f 100644
--- a/rialto/common/utils.py
+++ b/rialto/common/utils.py
@@ -19,10 +19,11 @@
 
 import pyspark.sql.functions as F
 import yaml
-from env_yaml import EnvLoader
 from pyspark.sql import DataFrame
 from pyspark.sql.types import FloatType
 
+from rialto.common.env_yaml import EnvLoader
+
 
 def load_yaml(path: str) -> Any:
     """
diff --git a/tests/common/test_yaml.py b/tests/common/test_yaml.py
new file mode 100644
index 0000000..9d63b66
--- /dev/null
+++ b/tests/common/test_yaml.py
@@ -0,0 +1,81 @@
+import os
+
+import pytest
+import yaml
+
+from rialto.common.env_yaml import EnvLoader
+
+
+def test_plain():
+    data = {"a": "string_value", "b": 2}
+    cfg = """
+    a: string_value
+    b: 2
+    """
+    assert yaml.load(cfg, EnvLoader) == data
+
+
+def test_full_sub_default():
+    data = {"a": "default_value", "b": 2}
+    cfg = """
+    a: ${EMPTY_VAR:default_value}
+    b: 2
+    """
+    assert yaml.load(cfg, EnvLoader) == data
+
+
+def test_full_sub_env():
+    os.environ["FILLED_VAR"] = "env_value"
+    data = {"a": "env_value", "b": 2}
+    cfg = """
+    a: ${FILLED_VAR:default_value}
+    b: 2
+    """
+    assert yaml.load(cfg, EnvLoader) == data
+
+
+def test_partial_sub_start():
+    data = {"a": "start_string", "b": 2}
+    cfg = """
+    a: ${START_VAR:start}_string
+    b: 2
+    """
+    assert yaml.load(cfg, EnvLoader) == data
+
+
+def test_partial_sub_end():
+    data = {"a": "string_end", "b": 2}
+    cfg = """
+    a: string_${END_VAR:end}
+    b: 2
+    """
+    assert yaml.load(cfg, EnvLoader) == data
+
+
+def test_partial_sub_mid():
+    data = {"a": "string_mid_sub", "b": 2}
+    cfg = """
+    a: string_${MID_VAR:mid}_sub
+    b: 2
+    """
+    assert yaml.load(cfg, EnvLoader) == data
+
+
+def test_partial_sub_no_default_no_value():
+    with pytest.raises(Exception) as e:
+        cfg = """
+        a: string_${MANDATORY_VAL_MISSING}_sub
+        b: 2
+        """
+        assert yaml.load(cfg, EnvLoader)
+    assert str(e.value) == "Environment variable MANDATORY_VAL_MISSING has no assigned value"
+
+
+def test_partial_sub_no_default():
+    os.environ["MANDATORY_VAL"] = "mandatory_value"
+    data = {"a": "string_mandatory_value_sub", "b": 2}
+    cfg = """
+    a: string_${MANDATORY_VAL}_sub
+    b: 2
+    """
+    assert yaml.load(cfg, EnvLoader) == data