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2004 Prius - water in the rear battery compartment

I have a 2004 Prius which began smelling musty. I discovered water in the trunk area, which I was able to drain by removing the plugs in the spare area. BUT, there is also water standing in the small well in which the battery sits - where there is no plug. The battery is encased in plastic so that the water does not actually get into the battery but I’m afraid of what accumulated moisture may do to the electronics. Forum chat indicates others with the problem but no one seems to have an idea exactly where the water might be coming from. Any clues? Water leak around the rear light cover? Any solutions that don’t cost an arm and a leg?

Unfortunately I don’t have a solution - rather, we own a '04 and an '07 Prius and by sheer coincidence I just found water under the battery in both of them. That doesn’t seem healthy for the people and the car. My repair shop (whose owner is also a Prius owner) hasn’t seen anything like that. How do you test where it’s coming in? Water hose? It’s too much water for condensation, I think.

Consider putting someone in the trunk area with a flashlight and going through a touch-free car wash.

I gave up on Toyota rear leaks long ago and just open up all the drains by removing the rubber plugs. I hope somebody can find the solution. I usually check for window leaks with a water bottle filled with caar wash soap, diluted so as not to waste it or gum up everything. With all windows closed, vent system on outside air, squirt soapy water on all window edges. Huge amounts of bubbles will be a sign of leaks.

It should work around tail lights too.

Yep. I just found the drain plug. This little compartment seems to be built to hold water. It’s low enough to collect water from through the car. Maybe it is built for that. I guess they know why the put the drain plug in.

Cars Aren’t Supposed To Accumulate Water To Be Drained By Pulling A Drain Plug. This Car Has A Problem. Water Will Eventually Cause Problems, At Least Corrosion Problems, Maybe Mold, Bacteria, Window Fogging, Electrical Problems, Etcetera.

You need to locate the leak(s) and fix the problem before it becomes a major problem.
"I have a 2004 Prius which began smelling musty. " This is Mother Nature’s way of giving you a warning.


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