Complex sentence: It was possibly in use until as late as the 9th century, well after the fall of Rome, however, lack of maintenance after the 4th century meant that it became increasingly clogged by mineral deposits and debris that eventually choked off the flow of water.
Split into simpler sentences: It was possibly in use until as late as the 9th century, well after the fall of Rome. However, lack of maintenance after the 4th century meant that it became increasingly clogged by mineral deposits and debris that eventually choked off the flow of water.