The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Vintage (2 members)
- Visions (26 members)
- Voluntary simplicity (5 members)
- Vulca (6 members)
- Walden Ecovillage (6 members)
- Wales (12 members)
- Wales files (4 members)
- Wales images (0 members)
- Wales sustainable community action topics (1 member)
- Washington (state) (4 members)
- Washington (state) files (5 members)
- Washington (state) images (0 members)
- Waste (53 members)
- Waste heat recovery (1 member)
- Waste management (127 members)
- Waste to energy (7 members)
- Wastewater (48 members)
- Wastewater treatment (20 members)
- Water (397 members)
- Water Filter (1 member)
- Water Wheel (1 member)
- Water and sanitation for developing countries (37 members)
- Water conservation (47 members)
- Water disinfection (5 members)
- Water distribution (13 members)
- Water filters (35 members)
- Water filtration (8 members)
- Water heating (15 members)
- Water pollution (10 members)
- Water purification (99 members)
- Water quality (54 members)
- Water recycling (5 members)
- Water supply (45 members)
- Water treatment (41 members)
- Water use (1 member)
- Water videos (53 members)
- Waterborne diseases (3 members)
- Watering (1 member)
- Waterpod (19 members)
- Watershed Water Quality Monitoring Project (8 members)
- Wattle and daub (5 members)
- Weather (3 members)
- Web platforms (2 members)
- Webcams (1 member)
- Websites (4 members)
- Wellness (1 member)
- West Midlands (5 members)
- West Midlands files (4 members)
- West Midlands images (0 members)
- Western (0 members)