Trickling water/grinding noise when braking

I know next to nothing about cars but would like some advice before I take in my car so I don’t get completely taken advantage of. Recently when I put on the brakes it sounds like there is water running from the back of the car under the floor, and then it’s finished off by a awful grinding noise. I assume I need new rear brake pads, but I’m puzzled by the fluid noise. I live in Arizona and it hasn’t been raining, so it’s definitely not just rainwater trapped somewhere. Any advice would be appreciated.

I doubt if the water noise is related to the brakes. You may be low on coolant – check this yourself and top up if necessary.

Take the car into the shop for routine brake service. You can consider the noise problem later, if it still exists.