| Name | Location | County | Country | Power source | Type | Function | River |
| Apsley Mill, Apsley | Apsley | Hertfordshire | United Kingdom | Water | Watermill | Paper mill | Gade |
| Frogmore Paper Mill, Apsley | Apsley | Hertfordshire | United Kingdom | Water | Watermill | Paper mill | Gade |
| Grove Mill, Watford | Watford | Hertfordshire | United Kingdom | Water | Watermill | Corn mill | Gade |
| Hunton Bridge Mill, Hunton Bridge | Hunton Bridge | Hertfordshire | United Kingdom | Water | Watermill | Corn mill | Gade |
| Kings Langley Mill, Kings Langley | Kings Langley | Hertfordshire | United Kingdom | Electricity, Steam, Water | Roller flour mill, Watermill | Corn mill | Gade |
| Old Mill, Cassiobury Park | Watford | Hertfordshire | United Kingdom | Water | Watermill | Pumping mill/wheel | Gade |
| Piccott's End Mill, Hemel Hempstead | Hemel Hempstead | Hertfordshire | United Kingdom | Water | Watermill | Corn mill | Gade |