Under the driver's seat and back wet

Hello friends, my driver's left side of the car and the rear lower part smelled wet, but not petrol, what can I do?

the problem is probably missing from the heater core seal. related topic

I thought it was petrol, but like water, would this be antifreeze?

Unfortunately, when used with water for a long time, this type of problem is unfortunately likely to happen in every vehicle. Because the anti-freeze has an abrasive protective feature. As you can see in the photos in the link, the seals must be changed and the missing screws must be completed.