The **windshield wiper system** is essential for keeping the vehicle's front glass clean, thus ensuring good visibility while driving. This system is complemented by the **windshield washer**, which sprays a jet of liquid onto the glass to facilitate cleaning.

- It is crucial to **check the liquid level** in the windshield washer reservoir and refill it when necessary. This ensures that the system functions correctly and that the wiper can effectively clean the glass.

- Although special liquids can be used for the windshield washer, it is also possible to use water mixed with a little detergent.

Therefore, it is important to perform regular maintenance on the system, ensuring that the liquid reservoir is always full. This confirms that the **correct answer** is that the windshield wiper system **requires us to check the water level in its reservoir**.