if you don't see a leak, maybe its leaking near the top or exhaust and burning off. or its leaking inside the motor. check the engine oil, see if its milkshaky, or overfill. or check the tailpipe.
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JP is right. have you changed your oil after your water dissappeared?
If you access to a dye and a floresent light to check if you have external leaks cuz it could of have steamed off before it hits the ground due to your exhaust.