Aspects herein are directed to a system that includes a storage tank, a mounting component, and a pump apparatus. The storage tank is configured to be placed within a volume of space between a false floor and an actual floor of a vehicle. The storage tank is further configured to store liquid. The system further includes a mounting component coupled to a first surface of the storage tank. The system also includes a pump apparatus coupled to a second surface of the mounting component. The pump apparatus is also configured to cause the liquid to be extracted from the storage tank and dispersed outside of the storage tank.

A method for calibrating a rain sensor (3), the rain sensor (3) being configured to measure a quantity of rain on a window (101) of a vehicle (100), the rain sensor (3) including a transmitter (4) and a receiver (5), the transmitter (4) being configured to emit or transmit light to the window (101) and the receiver (5) being configured to receive measurement light that is emitted or transmitted by the transmitter (4) and guided to the receiver (5) by the window (101); the method comprising: varying (S1) an incidence angle () of the light emitted or transmitted by the transmitter (4) to the window (101).