Sounds like you need to dig out cavemanocs toilet cooled system 
That was a very "cool" project hehe
btw - you claim that the dew point in your location is 8deg. The dew point varies according to atmospheric conditions (humidity etc) so to say that you as long as you keep the water temp above 8deg you won't get condensation is wrong. Indoors the atmospheric conditions are going to be quite different to outside so it's hard to know what the dew point will be. If the water pipes are cooler than your room temperature you will run the risk of condensation. Try feeling any of the mains water pipes in your house - the water will probably be around 12deg, but i bet the pipes are still damp from condensation.
Marc
That was a very "cool" project hehebtw - you claim that the dew point in your location is 8deg. The dew point varies according to atmospheric conditions (humidity etc) so to say that you as long as you keep the water temp above 8deg you won't get condensation is wrong. Indoors the atmospheric conditions are going to be quite different to outside so it's hard to know what the dew point will be. If the water pipes are cooler than your room temperature you will run the risk of condensation. Try feeling any of the mains water pipes in your house - the water will probably be around 12deg, but i bet the pipes are still damp from condensation.
Marc