You have a leak. The leak can be from the pump or any of the fittings. You may also have a leak at the rack & pinion.
You will have to keep adding power steering fluid.
If the power steering rack is leaking, it is likely an seal or a gasket. Replacing the seal or gasket should stop the leak.
The cost of a power steering leak repair depends on the leak placement and the car. A filler cap replacement might be 5.00, while a leak causing a steering rack replacement could be 750.00 or more.
The best way is to replaced the entire rack assembly.
could be several places, power steering hose, rack and pinion (or steering gear box) or power steering pump.
In order of MY observations: connections, hoses, power steering pump and finally rack or steering gear, although rack is becomming much more common.
We had to replace the rack and pinion in our 2005 T&C. The only symptom we had was the power steering fluid was leaking.
Check your hoses from the power steering reservoir for cracks in them and also check the power steering rack on the firewall to see if the rubber seals on the ends of the rack are leaking, maybe the reservoir itself is leaking, have it checked out.
When a power steering rack leaks you either have to rebuild it with a rebuild kit found at your local parts store or replace it completely. There is no quick repair for that.
Rack and pinion, power box, and power rack steering.
Check to see where leak originates could be: Leaking pump seal Leaking high or low pressure hose Could be steering rack