Well, you said it was leaking through a bolt by the coolant container. That is where the leak is. More than likely the reservoir is leaking.
AnswerI had a 2000taurus that had a messed up reservoir leak right by a nub that held it in place. temporarily switched it out for a used one, that one cracked as well. had to buy a new one from Ford costing about $60.00If a vehicle is loosing coolant then there is a leak. If no leak is visible then the coolant could be leaking into the oil, or leaking into a cylinder and being blown out through the exhaust.
Leaking heater core
You should able to tell if it's leaking so I assume that you are not seeing any coolant where you park so it's a good chance you got a blown head gasket and the coolant is leaking in your cylinders and being burned off or leaking into your oil. Check your oil after running and if it is foamy it has coolant in it.
1) Your engine is overheating and the coolant is boiling. Or 2) Exhaust is leaking into the coolant, probably through a bad head gasket or cracked head.
Probably leaking heater core.If not repairable get one from junkyard.
Can be condensation which is normal or can be coolant if you have a blown head gasket.
If it's leaking from INSIDE the firewall (away from the engine compartment) you probably have a leaking heater control valve or damaged heater core.
If your heater core is LEAKING engine coolant so that your engine coolant level drops too low or the engine coolant is lost completely and causes your engine to overheat then your engine can be damaged beside the mess the leaking coolant makes inside your vehicle ( you might be able to just temporarily bypass the heater core so that no engine coolant is flowing through the heater core )
Means that your heater core is leaking coolant. Has to be replaced.
cracked head, leaking head gasket
I would suspect a leaking water pump, if I remember correctly it is mounted right in front of the timing cover and if it is leaking from the back the water will find it's way out somehow.
The only hose connections at the firewall that contain coolant are the connections at the heater core. You either have a loose clamp or the compression fitting between the steel and metal parts of the hose itself are leaking. If there is coolant leaking out of an drain at the bottom area of the firewall, there's a good chance that it's leaking from the heater core itself, through a drain pipe which is the same drain pipe that removes water condensation from the air conditioning.