Upflush Toilet Venting

An upflush toilet is a type of installation for bathrooms, kitchens, and wet bars below the existing drain line. Upflush toilets are typically installed in retrofitted basements. Installing an upflush mechanism is often cheaper than trenching for a new, lower drain line. A motorized pump plugged into a GFI moves wastewater uphill to the point where the discharge pipe meets the main drain line.

These systems must also be vented in the same manner as traditional drain lines. The plumbing vents terminate in the vent stacks at the roof of your building. These vents exhaust methane and sewer gas up and away from the building's occupied spaces and allow the pressure in the drains to equalize. Sewer gases are hazardous to your health so proper drain venting is a very serious matter. The upflush toilet system should be designed and installed by a licensed plumber.

Planning for an Upflush Toilet Venting System

There are many different ways to run the plumbing vent lines. No configuration is incorrect as long as it complies with local building codes. However, some methods may be cheaper and easier to install than other alternatives. In general, you will want to avoid breaking through concrete walls or floors. If it is convenient to tie the drain and vent lines for the upflush system into the main lines somewhere inside the building, this is usually the best approach. However, tying in a vent line improperly can cause siphoning from other fixtures when the toilet is flushed.

If you need to run a vent line outside of the building, it has to terminate above the roof line. If you only run the vent line from the basement to ground level, sewer gases may be pulled inside by fans or through open windows. If you are installing especially deep or far from the drain line consider a macerating toilet. This toilet uses blades to grind up solids for easier pumping.

Installation of Vent Pipes

Use 4 inch PVC pipes joined with pipe cement for the drain vents. Fasten the pipes to the walls and ceiling with mounting brackets and pipe hangers. Install a backflow prevention valve on the discharge pipe. There are essentially two types of venting options. If the fixture is installed within five feet of an existing main vent stack, you can use a direct vent. A single drain line is connected directly to a vent stack which terminates above the roofline. If the distance from the fixture to the vent stack is too great, the fixture will not drain properly. Using a higher diameter pipe allows you to cover greater distances. Also, you cannot overload a vent stack. Surges of water create vacuums that cause siphoning at other fixtures. Consult the plumbing code for exact specifications. When direct venting is not possible, use a wet vent and dry vent arrangement. The dry vent goes up to the vent stack and the wet vent goes down to the main drain line for the room.