The amount of water you need for hiking depends on many things; your level of fitness, humidity, temperature, how much you exert yourself and more.
You need to replace the amount of water you lost through sweat and respiration or you risk dehydration which may result in muscle cramps, tiredness and loss of strength. Prolonged dehydration may cause dizziness, nausea and worse, heatstroke.
In general, a person can lose up to 1.5 litres of water in 2 or 3 hours. You can lose more than 5 litres more water after 7 hours. A bottle of water is hardly ever going to be enough. You need to carry at least four bottles if you’re going to be hiking that long.
A hydration pack can be useful because it allows you to drink handsfree and you don’t have to worry about empty bottles. There are usually outer pockets that you can use to keep your keys, wallet, phone, snacks and other small stuff.
How much water do you carry on a day hike?