The prices should not go up a lot, because if they did, farming would become unprofitable.
E.g., tomato farming produces around $4000 worth of produce per acre and year[0], and requires 2.5 feet applied water. ($4000/acre)/(2.5 feet) = 0.5 cents/gallon. If the water got that expensive they'd need to stop growing tomatoes, since just the water would already cost more than the produce would be worth.
By contrast, residential water is 0.7 cents per gallon[1], so the prices involved are really tiny compared to what human users are already paying.
You mean farming of water-intensive crops would become unprofitable. Yeah that is fine.
The flip side of this is that it never was profitable to begin with and only was done because citizens gave enormous handouts to these companies (paying for all their water). You can keep doing that, but make it more explicit: Make them pay for all the water, but give them a subsidy of $X and change it if they waste water.
Noooo… tomatoes would just get more expensive to the point where demand balances out. You need to think beyond the first effect. All of this stuff ripples through the entire market.
You can still grow tomatoes outside California though, surely production would shift to a place with cheaper water? And if the prices are too high people would stop buying tomatoes.
I agree that the prices would not be exactly the same, my point is just that these prices are still extremely low. You don't need to fear people dying from dehydration (like the comment above suggested).
E.g., tomato farming produces around $4000 worth of produce per acre and year[0], and requires 2.5 feet applied water. ($4000/acre)/(2.5 feet) = 0.5 cents/gallon. If the water got that expensive they'd need to stop growing tomatoes, since just the water would already cost more than the produce would be worth.
By contrast, residential water is 0.7 cents per gallon[1], so the prices involved are really tiny compared to what human users are already paying.
[0] https://www.nass.usda.gov/Quick_Stats/Ag_Overview/stateOverv...
[1] https://www.calwater.com/docs/rates/rates_tariffs/ela/202201...