Final answer:
The restrictions on the wear of personal hydration systems with the ACU are outlined in the AR 670-1 regulation. Personal hydration systems are not allowed on the front of the ACU, but can be attached to the back of the vest or plate carrier.
Step-by-step explanation:
The restrictions on the wear of personal hydration systems with the ACU (Army Combat Uniform) are outlined in the AR 670-1, which is the regulation for wear and appearance of Army uniforms. According to the regulation, soldiers are prohibited from wearing personal hydration systems on the front of their ACU. However, they are allowed to attach a hydration system on the back of their vest or plate carrier.
For example, soldiers can use a CamelBak or similar hydration bladder that is compatible with their vest or plate carrier. This allows them to stay hydrated without compromising the uniform's appearance or functionality. The purpose of these restrictions is to maintain a professional and cohesive appearance among soldiers while ensuring they have access to necessary hydration during their duties.