diff --git a/custom_components/localthings/registry/capabilities/water_purifier.py b/custom_components/localthings/registry/capabilities/water_purifier.py
index 159f11a..b04e2e9 100644
--- a/custom_components/localthings/registry/capabilities/water_purifier.py
+++ b/custom_components/localthings/registry/capabilities/water_purifier.py
@@ -175,11 +175,23 @@ FAVORITE_HOTWATER = Capability(
                    write_fn=lambda p, rep, href=None: (
                        ['favorite', 'hotwater', 'vs', '0'],
                        {'x.com.samsung.da.switchHotwater': 'Locked' if p == 'On' else 'Unlocked'})),
+        # Issue #196: `supportedList` is only the four *fixed* presets
+        # (e.g. ['40', '75', '85', '90']) -- the SmartThings app also lets
+        # the user add one custom value to their own display list via its
+        # "temperatures to display" editor (a wheel picker bounded by
+        # /setting/waterpurifier/vs/0's hotwaterRange, separate resource),
+        # and that custom value shows up in `showList`
+        # (['40', '50', '75', '85', '90'] here) but never in
+        # `supportedList`. Reading options from `supportedList` meant a
+        # unit whose current default *was* that custom value rendered as
+        # "unknown" -- not a coverage gap, just the wrong field. `showList`
+        # is a superset of `supportedList` that always includes whatever
+        # the current default actually is, custom or not.
         SelectDesc(key='favorite_hotwater_temperature',
                    field='x.com.samsung.da.favorite.defaultTemperature',
                    icon='mdi:thermometer',
                    entity_category='config',
-                   options_field='x.com.samsung.da.favorite.supportedList',
+                   options_field='x.com.samsung.da.favorite.showList',
                    write_fn=lambda p, rep, href=None: (
                        ['favorite', 'hotwater', 'vs', '0'],
                        {'x.com.samsung.da.favorite.defaultTemperature': p})),
diff --git a/tests/test_water_purifier_capabilities.py b/tests/test_water_purifier_capabilities.py
index 432eb8a..5721fd7 100644
--- a/tests/test_water_purifier_capabilities.py
+++ b/tests/test_water_purifier_capabilities.py
@@ -281,9 +281,17 @@ def test_hotwater_lock_fallback_gating_across_status_lock_states():
     assert fallback.exists_fn({}, {}) is False
 
 
-def test_favorite_hotwater_temperature_options_come_from_live_supported_list():
+def test_favorite_hotwater_temperature_options_come_from_live_show_list():
+    """`supportedList` is only the four fixed presets -- `showList` is a
+    superset that also carries the one custom value (if any) the
+    SmartThings app's "temperatures to display" editor let the user add,
+    and always includes whatever the current default actually is. Reading
+    `supportedList` meant a unit whose default *was* that custom value
+    rendered as 'unknown' in HA (issue #196) -- see the ailite fixture's
+    version of this test below for the case that actually exercises it
+    (this fixture's showList == supportedList, no custom value set)."""
     desc = _desc_coffee('favorite_hotwater_temperature')
-    assert desc.options_field == 'x.com.samsung.da.favorite.supportedList'
+    assert desc.options_field == 'x.com.samsung.da.favorite.showList'
 
 
 def test_coffee_recipe_hrefs_are_ignored_not_guessed():
@@ -361,6 +369,24 @@ def test_ailite_hot_water_temperature_gated_off_without_supported_list():
     assert 'hot_water_temperature' not in state
 
 
+def test_ailite_favorite_hotwater_temperature_options_include_the_custom_value():
+    """This board's real dump (issue #196) is the concrete case: the user
+    added a custom 50C value via the SmartThings app's "temperatures to
+    display" editor, so favorite.showList is
+    ['40', '50', '75', '85', '90'] while favorite.supportedList stays the
+    fixed ['40', '75', '85', '90'] -- '50' only ever appears in showList.
+    Whichever of the two the descriptor reads from, a default temperature
+    of '50' would render as HA's 'unknown' state unless that field's raw
+    option list actually contains '50'."""
+    desc = _desc_ailite('favorite_hotwater_temperature')
+    assert desc.options_field == 'x.com.samsung.da.favorite.showList'
+    _, resources = _water_purifier_ailite()
+    rep = resources['/favorite/hotwater/vs/0']
+    assert rep['x.com.samsung.da.favorite.defaultTemperature'] in rep[desc.options_field]
+    assert '50' not in rep['x.com.samsung.da.favorite.supportedList']
+    assert '50' in rep['x.com.samsung.da.favorite.showList']
+
+
 def test_ailite_sound_mode_options_come_from_live_supported_modes():
     """This board's supportedModes (voice/fixedTone/mute) differs from both
     laundry.SOUND_MODE's hardcoded voice/tone/mute and air_purifier.SOUND_MODE's