Solutions Heavy water has 4 entries with similar clues

• 3-letter words
• nor"Water, water, every where, / ... any drop to drink": "The Rime of the Ancient Mariner"
• 7-letter words
• breakerSmall cask for fresh water - or sea water?
• oilskinHeavy-duty, waterproof
• 9-letter words
• tarpaulinHeavy waterproof cover