With Bountiful Fares installed, its Cups hold graded water like a glass bottle, its teas, ciders and stews restore thirst, and sea water can't be fermented or brewed into tea.
Supported versions
Fabric and NeoForge on Minecraft 1.21.1, with 
Bountiful Fares 3.0.13, which needs NexusLib. Its older versions for 1.20 are no longer updated and are not supported.
The Cup
A Cup works like a glass bottle. Filled from water, it gets that water's grade, so a Cup filled from the sea holds sea water. A Water Cup is drunk like a water bottle and restores the same thirst, with the same chance of sickness from dirty water.
Water Cups pour into and draw from cauldrons, the Hanging Pot and the Copper Distiller one drink at a time, and the water keeps its grade.
Fermentation and tea
The Fermentation Vessel won't take sea water. Fresh water of any grade still works, and what comes out is safe to drink.
Tea crafted from a Water Cup of sea water won't work, and neither will a Sponge Cake made with buckets of sea water.
Drinks and food
| Item | Thirst | Quenched |
|---|---|---|
| Every tea, Apple, Hoary and Plum Cider, stews | 6 | 4 |
| Mead, Maple Mead | 5 | 2 |
| Coconut Milk | 4 | 0 |
| Elderberry and Lapisberry Wine | 3 | 1 |
| Compotes | 3 | 2 |
| Medleys, Sea Salad, Oranges, Lemons, Plums, Hoary Apples, Passion Fruit, Spongekin Slices | 2 | 0 |
| Elderberries, Lapisberries | 1 | 0 |
Maple Mead only exists with No Man's Land installed. Every value can be changed in the config.