Zoeller’s Model 53, Liberty’s 250-Series, Wayne’s CDU800 and Little Giant’s 6 Series all have a 1-1/2" threaded discharge. Run the discharge pipe at least that size.
Discharge size by pump
| Pump | Discharge | The maker on the pipe |
|---|---|---|
| Zoeller Model 53 | 1-1/2" NPT | No discharge pipe smaller than the pump discharge, with a check valve and a union in the line |
| Liberty 250-Series | 1-1/2" threaded | Not below the size on the pump, and Schedule 40 PVC pressure pipe recommended |
| Wayne CDU800 | 1-1/2" NPT | Rigid PVC required, and no flex hose in a permanent installation |
| Little Giant 6 Series | 1-1/2" female pipe thread; some models come with a 1-1/4" FNPT reducing bushing | No piping smaller than the pump discharge, and pipe joint compound at every connection |
Other models from these makers can differ. The size is on the pump’s spec sheet or in its manual.
1-1/4 or 1-1/2 inch pipe?
Some of Little Giant’s 6 Series pumps come with a 1-1/4" reducing bushing, so the pump can take 1-1/4" pipe. Its manual still says not to use piping smaller than the pump discharge, and the IPC (section 1113.1.4) asks for pipe and fittings the same size as, or larger than, the pump’s discharge tapping. On a 1-1/2" discharge, 1-1/2" pipe meets both. Liberty adds that a long run may need a larger pipe to cut friction loss. Local code decides, so check with your building department.
For what 1-1/2" pipe measures across, see 1-1/2" pipe OD.
What goes in the discharge line
- A check valve. Zoeller, Liberty, Wayne and Little Giant all call for one, so water in the pipe can’t run back into the pit after each cycle. Zoeller’s 30-0181 check valve fits 1-1/4" or 1-1/2" Schedule 40 PVC, with rubber couplings or by solvent welding.
- A union. Zoeller, Liberty and Little Giant call for one just above the floor or the basin cover, so the pump can come out for service.
- A gate or ball valve where code calls for one. The IPC asks for a gate valve and a full-flow check valve, and for one- and two-family homes only the check valve. Wayne says to add a gate or ball valve if local code requires it.
- Check valve direction. Makers differ. Little Giant’s manual puts the check valve in horizontally, because solids can settle in a vertical one. Zoeller rates its 30-0181 for either.
The relief hole
With a check valve in the line, Zoeller, Liberty and Little Giant call for a small hole in the discharge pipe between the pump and the check valve, to let trapped air out. The size differs by maker. Zoeller says about 3/16", Liberty 1/8", and Little Giant 1/8" or 3/16". Wayne’s CDU800 has a top suction design that, in Wayne’s words, needs no weep holes. Zoeller puts the hole below the basin cover, and a small stream from it while the pump runs is normal. Follow your own pump’s manual.
Where the water goes
Where a sump pump may discharge is set by local code. Little Giant lists the house drainage system, a dry well, a splash block or a storm drain, depending on local plumbing codes. Wayne’s manual has the water carried at least 3 feet from the foundation, with the pipe sloping down and away where it can freeze. Ask your building department before you tie into any drain or sewer.
Unplug the pump before you touch it or its discharge pipe. If the floor around the pit is flooded, stay out of the water and have your electric company or a licensed electrician shut off the power first. Electrical work for a sump pump, such as its outlet or circuit, is a job for a licensed electrician.