Outdoor Sewage Systems

Q. "What does 'AFD' stand for?"
A. The abbreviation "AFD" stands for Anti-flotation device. In this case it is a collar attached to the bottom of the basin to reduce or eliminate the basin from being forced out of the ground when the water table is high.

Q. "Can I mount the check valve horizontally?"
A.It is normally recommended that the check valve (or check/ball valve combination) is mounted vertically, however each can be mounted horizontally. The installation for each unit is similar; the check valve hinge must be at the top.

Q. "We noticed some of the basins are listed as 'Premium' Polyethylene Structural Foam basins. What makes them 'premium'?"
A.The "Premium" Polyethylene Structural Foam basins have torque arrestors molded into the bottom of the basin to keep the pump in place during operation and to prevent damage to the pump during shipping.

Q. "Why is a 3/16" vent hole pre-drilled into the discharge tube?"
A.A 3/16" vent hole, also known as an air bleed, is drilled into the discharge pipe located in the basin between the pump and check valve to prevent the pump from becoming air locked. This hole is normally drilled a few inches above the pumps "on" level. When a check valve is installed on the discharge pipe, air can be trapped under or behind the check valve. This trapped air blocks the pipe when the pump turns on preventing water to be pumped beyond the trapped air. If a pump becomes air locked it will continue to run but not push water, causing the pump to eventually burn out. This vent hole (air-bleed) allows the air to escape into the basin and helps prevent the pump from burning out.

Q. "What does it mean when it states 18' shut off head? "
A.It means the pump will not move water beyond that point in height. If the pump shut off height is 18 feet and you put a pipe 17 feet 11 inches high straight up from the pump, water would still trickle over and out of the pipe. If you put a pipe at 18' straight up from the pump, while the pump continues to operate, water will just stay at that height in the pipe.

Q. "What is a vortex impeller and what does it do?"
A. A vortex impeller handles debris better than other impellers. Due to the design of the impeller itself, a whirlpool, or vortex, action is created to move the material, resulting in less clogs as vortex impellers are recessed and generally do not come in contact with solids at all. By contrast vane, or two-vane, impellers are in direct contact with the solids, and so can be more prone to being clogged. Below is an example of a vortex impeller.

Q. "How are these Zoeller Outdoor Pre-packaged systems normally installed?"
A.Installation is normally done by digging a hole at least 24" larger in diameter than the basin diameter to allow for a 12" backfill all around it. The backfill material should be 1/8" -3/4" pea gravel or 1/8" -1/2" crushed stone. The hole should be dug deep enough to allow for 12" of compacted backfill or 6" deep if a concrete pad will be required. Do not backfill until the inlet and discharge plumbing lines have been installed into the basin. The hole should be at least 10 feet from adjacent structures. The top of the basin should be flush with the top of the surface of the ground for access to the pump and basin. When located below grade a riser is recommended to bring the lid up to ground surface for easy access to the pump and interior of the basin. The installer will need to dig a trench and plumb the fixtures to drain into the 4" basin inlet which can be bushed down to 3" if needed. A trench will also need to be dug for the discharge pipe and for the electrical conduit. The sewage discharge exits from the side of the basin to be plumbed horizontally underground and tied into the main drain or directly into the septic tank if dictated by ground elevations.

Installing a check/ball valve combination in the discharge pipe allows you to stop back flow from reaching the sump while servicing it. The electrical needs to be protected from weather conditions either in an approved electrical box rated for outdoors, or run back into the building structure. Venting for outdoor systems can normally be vented on the basin cover as necessary, but must be in accordance to all applicable National, State, and Local plumbing codes. Do NOT use an automatic plumbing vent device or air admittance valve that allows air to flow in but not to flow out, similar to "Provent®", or "Studor®" air admittance valves. You might consider using an Odorhog™ vent pipe system. Please remember, all discharge and venting plumbing, must be installed to meet local codes. Most Zoeller sewage pump systems are packaged for shipping with environmentally safe water soluble peanuts that will not need to be removed. Once the sewage system is installed and in use, the fluid level will rise and trigger the float switch which then turns on the pump and pumps the sewage through the check valve and into the regular drain line or septic tank.   Click here for typical installation.

Reminder: A check valve is needed for these sewage sump systems and for your convenience we offer a few choices giving you the freedom to choose the one that is best for your application. All of the Zoeller check valves sold separately on this page can be installed on vertical or horizontal pipe.