hi guys,
i noticed that i have to keep topping the coolant in my reservoir tank and i have checked and cant seem to find anywhere there is leakage on the radiator. dont know wat the probs might be, can anyone give me an idea of wat the probs might be.

You didn't say which car this is and the frequency of topping up.
How old is the car and was it retaining its water before this problem emerged?
You may have a blown head gasket.
Pull out the dip stick and check the bottom below the gauge markings. Does it have creamy deposits?
On the same dipstick does it have water droplets or creamy deposits? It should only show oil.
Check the oil filler cap. Do you have the same deposits on the cap.

This is not a 100% test but it is a fair indication that there are problems with the cooling system.

Also check that your radiator is not leaking or that you are losing water after driving the car.

Good luck

The plastic reservoir could also have had a little crack, therefore losing steam.