Hydration status can impact your strength levels in multiple ways. For one, dehydration can comprise the fluid in your muscle cells, making them smaller in size. Being dehydrated can also slow down your nervous system, which can have a negative effect on muscle-contraction speed and strength.
To avoid this, make sure to drink enough fluid every single day. A solid goal to shoot for is about one gallon of water per day. It's also important that you're staying hydrated both before and during your workout.
Before your workout, aim to get 15-20 ounces (444-591ml) of fluid, and during your workout drink 5-10 ounces (148-296ml) of water every 15 minutes or so. Make sure to rehydrate after your workout to replenish fluids lost through sweat.
Grab your water bottle and start squatting!