2014 Nissan Altima water leak on driver's side floor

Might be a plugged up evaporator drain. Some are harder to get to than others Doubt it's coolant given the age of car but won't know till you have a look. Good Luck!

Normally there are holes under dash for electrical wires. Make sure those are sealed. If not that then... Check the windshield rain can run run from pillar to firewall and then to floor. But its not coolant because the heater core is on passengers side. Thinking about it now your condensation drain tube can be clogged and draining back into your car too.