diff --git a/geetools/ee_image_collection.py b/geetools/ee_image_collection.py
index 66ce2933..65112a16 100644
--- a/geetools/ee_image_collection.py
+++ b/geetools/ee_image_collection.py
@@ -881,10 +881,13 @@ def groupInterval(self, unit: str = "month", duration: int = 1) -> ee.List:
                 split = collection.geetools.groupInterval("month", 1)
                 print(split.getInfo())
         """
+        sizeName = "__geetools_generated_size__"  # set generated properties name
+
         # as everything is relyin on the "system:time_start" property
         # we sort the image collection in the first place. In most collection it will change nothing
         # so free of charge unless for plumbing
         ic = self._obj.sort("system:time_start")
+        toCopy = ic.first().propertyNames()
 
         # transform the interval into a duration in milliseconds
         # I can use the DateRangeAccessor as it's imported earlier in the __init__.py file
@@ -896,6 +899,20 @@ def groupInterval(self, unit: str = "month", duration: int = 1) -> ee.List:
             lambda dr: ic.filterDate(ee.DateRange(dr).start(), ee.DateRange(dr).end())
         )
 
+        def add_size(ic):
+            ic = ee.ImageCollection(ic)
+            return ic.set({sizeName: ic.size()})
+
+        def delete_size_property(ic):
+            ic = ee.ImageCollection(ic)
+            return ee.ImageCollection(ic.copyProperties(ic, properties=toCopy))
+
+        imageCollectionList = (
+            imageCollectionList.map(add_size)
+            .filter(ee.Filter.gt(sizeName, 0))
+            .map(delete_size_property)
+        )
+
         return ee.List(imageCollectionList)
 
     def reduceInterval(
@@ -943,16 +960,20 @@ def reduceInterval(
         red = getattr(ee.Reducer, reducer)() if isinstance(reducer, str) else reducer
 
         def reduce(ic):
-            timeList = ee.ImageCollection(ic).aggregate_array("system:time_start")
+            ic = ee.ImageCollection(ic)
+            timeList = ic.aggregate_array("system:time_start")
             start, end = timeList.get(0), timeList.get(-1)
-            bandNames = ee.ImageCollection(ic).first().bandNames()
-            image = ee.ImageCollection(ic).reduce(red).rename(bandNames)
+            firstImg = ic.first()
+            bandNames = firstImg.bandNames()
+            propertyNames = firstImg.propertyNames()
+            image = ic.reduce(red).rename(bandNames).copyProperties(firstImg, propertyNames)
             return image.set("system:time_start", start, "system:time_end", end)
 
         reducedImagesList = imageCollectionList.map(reduce)
 
         # set back the original properties
-        ic = ee.ImageCollection(reducedImagesList).copyProperties(self._obj)
+        propertyNames = self._obj.propertyNames()
+        ic = ee.ImageCollection(reducedImagesList).copyProperties(self._obj, propertyNames)
 
         return ee.ImageCollection(ic)
 
diff --git a/tests/test_ImageCollection.py b/tests/test_ImageCollection.py
index 7ddeb616..39d48e3f 100644
--- a/tests/test_ImageCollection.py
+++ b/tests/test_ImageCollection.py
@@ -297,6 +297,14 @@ def test_group_interval_with_interval_and_unit(self, jaxa_rainfall):
         assert grouped.size().getInfo() == 3
         assert ee.ImageCollection(grouped.get(0)).size().getInfo() == 24
 
+    def test_group_interval_drop_empty_collections(self, s2_sr):
+        ic = s2_sr.filterDate("2021-01-01", "2021-01-07")
+        grouped = ic.geetools.groupInterval(duration=1, unit="day")
+        # Each collection must not be empty
+        for i in range(grouped.size().getInfo()):
+            imgCollection = ee.ImageCollection(grouped.get(i))
+            assert imgCollection.size().getInfo() != 0
+
     def test_deprecated_make_equal_interval(self, jaxa_rainfall):
         # get 3 month worth of data and group it with default parameters
         ic = jaxa_rainfall.filterDate("2020-01-01", "2020-03-31")
@@ -340,6 +348,22 @@ def test_reduce_interval_with_non_existing_reducer_and_properties(self, jaxa_rai
         with pytest.raises(AttributeError):
             ic.geetools.reduceInterval("toto")
 
+    def test_reduce_interval_with_empty_days(self, s2_sr):
+        ic = s2_sr.filterDate("2021-01-01", "2021-01-07")
+        resultSize = ic.geetools.reduceInterval("mean", duration=1, unit="day").size().getInfo()
+        assert resultSize == 3
+
+    def test_reduce_interval_image_collection_with_system_id(self, s2_sr):
+        originalIc = s2_sr.filterDate("2021-01-01", "2021-01-07")
+        ic = originalIc.geetools.reduceInterval("mean", duration=1, unit="day")
+        assert "system:id" in ic.propertyNames().getInfo()
+
+    def test_reduce_interval_image_with_system_id(self, s2_sr):
+        originalIc = s2_sr.filterDate("2021-01-01", "2021-01-07")
+        ic = originalIc.geetools.reduceInterval("mean", duration=1, unit="day")
+        firstImg = ic.first()
+        assert "system:id" in firstImg.propertyNames().getInfo()
+
     def test_deprecated_reduce_equal_interval(self, jaxa_rainfall, amazonas, num_regression):
         # get 3 month worth of data and group it with default parameters
         ic = jaxa_rainfall.filterDate("2020-01-01", "2020-03-31")