I don’t tend to measure this exactly, but I think aiming for a minimum of 4-6 litres of fluids a day, and salting each meal with a few grinds of Himalayan pink salt or Sea salt should be adequate (Approx 1g salt per litre of water is a good guideline). If you sweat a lot, then increase your fluid intake and consider supplementing with electrolytes also.
Your body is very good at indicating when you need more fluid through thirst and if you’re urinating too frequently, increase salt intake.