You will need to drink two litres of water every day. This amount will increase if you participate in rigorous physical activity like combat. Fresh water sources are relatively easy to access to refill your water bottle as necessary, but different conditions may bring you extra thirst.
The GM should make a note to declare when the party is becoming thirsty two times per day. The party should also drink half a litre after every combat. If the party is deprived of water for 6 consecutive “thirsts,” they will pass out and perish of deprivation.
Thirst rules should only be employed in scenarios where water is not instantly and freely accessible, such as during extended travel.