Staying hydrated is crucial on treks as it can cause numerous problems. However, this starts before the adventure. It is essential to drink at least a litre a couple hours before the trek. This can limit the complications during the trek if you continue to have little water breaks throughout the trek. I personally bring a hydration bladder as I enjoy the convivence of it. As I do know people, who prefer water bottles, so there are other options. But never judge your hydration levels on how many times you urinate as it is not an effective method.
One way of judging your hydration levels is by evaluating the colour of your urine. NSW Royal Fire Service have a model they use to gauge their own hydration levels that are quite useful that can be found at https://twitter.com/lewshort14/status/422563558681890816/
Aside from the colour of the urine, another sign is headaches. If you ever get a headache while hiking, never disregard it! Your body is trying to tell you something.
Nevertheless, even though this blog is about dehydration, you must also be careful of drinking too much water. This can also be very dangerous. You need to find the perfect balance that suits your body.