Would any of you know what's the reservoir
capacity of the windshield washer on this car?
If not exactly, would it be less, or more than 1 US Gal. (3.8L) ?

Thanks for your attention.

 

Can only guess, less then 1 gal.

 

Thanks, Toyomoho.
Hmm... I just emptied a whole gallon of washer and it didn't overflow.
That means there is a leak, possibly a crack in my tank?

 

The quantity was only a guess based on filling experiences as Toyota does not list a volume. Suggest you top off the reservoir and wait for it to drop if leaking.

The tank can crack but not common. What is your climate like, it is possible for the washer fluid to freeze if its low temp rating is exceeded then the tank might crack.

Or perhaps a loose hose connected to the pump.

 

Yes, I've also considered all those possibilities.
It's been excessively cold here, but that's not the first time and our windshield washer is rated accordingly. As soon as the weather becomes friendlier, I'll be able to investigate. Will report on my findings right after. Thanks for your help.