Wastes from safes, drip pans, etc., should not be directly connected to any part of the drainage system.
The lower end of such a pipe should have a brass flap valve to prevent the passage of cellar air.
The overflow from the attic tank or other similar tank should not be directly connected to the drainage system, but should be discharged upon the roof or into an open fixture. It is often convenient to discharge this overflow into the flush tank of a water closet on a floor below the tank. This overflow should never be less than 1 1/4 in in size, and 1 1/4-in. pipe is often better.