The condensate trap extracts the discharge which gathers in the primary heating/cooling system. This is caused by the alterations in the pressure and temperature within those systems. A discharge pipe linked to the condensate trap then allows any held water passage out of the property. The water captured by a condensate trap may contain mild levels of acid due to carbon dioxode from the combustion process dissolving in the water. This is why the discharge pipe is almost always made of of plastic.