2005 audi a4, i have water in my floor board but it does not smell like coolant, what can it be

sorry ask a mechanic to have a look as it could be anything leaking from a hose to a water pump and everything inbetween ,cannot understand what possesed you to buy a petrol version though they are just jungle juice gobblers and at 10 dollars a gallon for petrol these sort of cars are not worth nothing here ,in the UK about a 1000pounds and not a lot more here in spain but a diesel ???? now your talking these fetch money

The only actual water under a car, would be from the
air conditioner or exhaust system on start up

Have you actually looked under there or felt & smelled the water,
to see if it is coolant.

The A/C condensor is also in that area and as it cools the air in the car it also removes moisture. This moisture will collect in a pan underneath the condensor and is supposed to drain out in the engine compartment. I would try to smell the water that is on your floorboards first. If it has a sweet smell and an "oily" type feel to it then your heater core probably has failed. If it is clear and odorless, then I would try to inspect the drain, at the firewall in the engine compartment for blockage.

does the check engine light come on or flash when the running issue starts? sounds like you have an ignition coil dropping out intermittenly.

If your car has a sunroof, one if the sunroof drains runs down through windshield post down through to bottom of the car. If it gets plugged it will back up into car. If it's coolant you're finding (sticky and smelling like coolant) your heater core is leaking

Check the coolant temperature sensor housing in back of the engine. This is made out of plastic on some model years A4 and eventually leaks coolant.

That sounds like you have bad fan switch it reads the temp.of the coolant and sends a signal to the computer to turn on the fan.

Could be thermostat this regulates the water flow around the engine to keep it cool sounds like it is sticking open when water gets hot!!

did you replace windshield?
do you have a sunroof?
these are the only places water could leak.
it could also be the condensation from the dehumidifier of the AC. maybe they forgot to reconnect the hose to expell the water.