When did you last clean it out. It should be drained and cleaned at least every 3-4 years.
Check where this rusty water is coming from. There are many possible causes.
I think it has something to with your pipes not your water. Your pipes are must probably rusty and it is coming out in the water.
Iron in the water would cause rusty stains in the toilet.
Sounds like you have a leaky heater core. You will need to replace the heater core and give the cooling system a good flushing, it shouldn't be rusty.
rusty water
lack of proper care. lack of proper (distilled) water in the radiator.
the reason for water coming out from under the dash is that a hose could have broke or you have a problem with your heater. your heater works off of the water in the radaitor and since it gets hot from the motor well it serculates threw the heater and that's who your heater works
Check your heater hoses, that's where the water ciruclates into the heater from the water pump.
It Might Cause tetanus at a certain point
Water on the floor that is not coming from the heater core is coming either from rain water leaking around a windshield seal or one of the firewall seals where hoses, wires or other components enter from the engine compartment.
Heater core? Inlet or outlet hose fitting at heater core?
ypu may have a busted heater core or a stuck thermostat im not for sure.