It is just a matter of knowing where the water sources will be along the way, trusting your filter and not forgetting to stop and get water when you have the opportunity before you get too low. If water is more scarce drink plenty at the water source to avoid having to carry as much. Also adjust to the conditions. You will need more when it is hot or very dry. Most p[laces you are likely to camp will be reasonably close to a water source so you can probably plan to filter the water you need for camp once you get there or at the last reliable water source if you are dry camping.
Modern filters like the Sawyers make it very easy to collect and treat water as you go...at least in the US.
Note: Most chemical methods and boiling take too long. UV is fast and it is great for international travel where even municipal water sources may be suspect, you want to be discrete and you need broader protection but it is a bit fragile for backpacking. Unlike filters, none of these methods remove the particles so they don't result in water that is necessarily pleasant to drink.