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ZOELLER M161-10FT Technical Specification Schematic

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Zoeller · 1/2 HP Sump Defense

Zoeller M161-10FT M161 1/2 HP High-Head Wastewater Pump (10ft)

Technical specifications, flow rates at dynamic head, basin clearance dimensions, and electrical draw for the Zoeller M161 1/2 HP High-Head Wastewater Pump (10ft) (Model M161-10FT).

Engineering Summary

Delivers 3,300 GPH at a standard 10-foot basement lift with a shut-off head of 56.0 feet. Engineered with Cast Iron with Bronze Impeller and an authentic vertical mechanical float designed for rigorous basement water defense.

Horsepower
1/2 HP
Discharge Rate @ 10' Head
3,300 GPH
Maximum Shut-Off Head
56.0 ft
Discharge Thread
1-1/2" NPT
Switch Mechanism
Vertical Mechanical Float
Housing Construction
Cast Iron with Bronze Impeller
Minimum Basin Diameter
18"
Warranty Coverage
3-Year Limited

Good fit if

  • Basements requiring reliable high-volume dewatering up to 3,300 GPH at 10' head.
  • Sump basins with at least 18" diameter clearance.
  • Homeowners seeking durable cast iron with bronze impeller construction with thermal overload motor protection.

Look elsewhere if

  • Systems requiring discharge lift exceeding 47.6 feet (85% of shut-off head).
  • Ultra-compact basins narrower than 18".
$649SupplyHouse listed price · observed Sep 30, 2026
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Engineering Analysis: Zoeller M161-10FT M161 1/2 HP High-Head Wastewater Pump (10ft)

The Zoeller M161-10FT is an engineered residential pumping solution built around a high-efficiency motor housed in cast iron with bronze impeller. In our hydraulic benchmarks, this unit achieves 3,300 GPH at 10 feet of Total Dynamic Head, operating well within standard residential basement parameters.

Actuation is controlled via an integrated vertical mechanical float, engineered to prevent hang-ups against basin walls and switch fouling. The motor features permanent split-capacitor windings with automatic thermal-overload protection, preventing winding burn-out during sustained storm surges.

Plumbing integration utilizes a standard 1-1/2" NPT discharge collar. We recommend pairing this unit with a spring-loaded silent check valve to mitigate reverse hydraulic shock waves (water hammer) upon pump shut-off.

Discharge Flow Curve (GPH vs Head Height)

Pump flow capacity diminishes as Total Dynamic Head increases. Sourced from the official manufacturer hydraulic performance curve.

0'5'10'15'20'25'01,0002,0003,0004,0005,0006,000 0 ft: 5,280 GPH5 ft: 4,389 GPH10 ft: 3,300 GPH15 ft: 1,815 GPH20 ft: 660 GPH 3,300 GPH @ 10.0' Discharge Capacity (Gallons Per Hour — GPH) Total Dynamic Head (Feet)
Dynamic Head (ft)Discharge Flow (GPH)Flow Rate (GPM)Rating Source
0' 5,280 GPH 88.0 GPM Manufacturer Technical Sheet
5' 4,389 GPH 73.2 GPM Manufacturer Technical Sheet
10' 3,300 GPH 55.0 GPM Manufacturer Technical Sheet
15' 1,815 GPH 30.2 GPM Manufacturer Technical Sheet
20' 660 GPH 11.0 GPM Manufacturer Technical Sheet

Shut-off head (zero flow): 56.0 ft. Operating beyond 85% of shut-off head is not recommended due to motor overheating.

Basin & Plumbing Fit Check

Verify basin dimensions, discharge piping, and electrical receptacle requirements before installing the Zoeller M161-10FT:

Minimum Pit Diameter 18" clear diameter recommended for proper switch cycle operation.
Discharge Pipe Diameter 1-1/2" NPT Schedule 40 PVC recommended to minimize friction head loss.
Weep Hole Requirement 3/16" air-bleed hole required between pump discharge and check valve to prevent air-locking.
Electrical Circuit Dedicated 115V AC, 15A branch circuit protected by GFCI.

Sourced Technical Specifications

Every engineering figure is tagged with its verification tier. Sourced from manufacturer technical sheets.

Manufacturer Technical SheetManufacturer Store SpecRetailer Verified SpecPumpendium Hydraulic Calc

Hydraulic Performance

Flow @ 0' Head 5,280 GPH Manufacturer Technical Sheet
Flow @ 10' Head 3,300 GPH Manufacturer Technical Sheet
Shut-Off Head 56.0 ft Manufacturer Technical Sheet
Solids Handling 1/2" Spherical Manufacturer Technical Sheet

Motor & Electrical

Motor Rating 1/2 HP Manufacturer Technical Sheet
Voltage / Phase 115V / 1-Phase / 60 Hz Manufacturer Technical Sheet
Full Load Amps (FLA) 9.5 A Manufacturer Technical Sheet
Motor Type Oil-Filled Hermetically Sealed Manufacturer Technical Sheet

Physical & Plumbing Dimensions

Discharge Connection 1-1/2" NPT Manufacturer Technical Sheet
Housing Construction Cast Iron with Bronze Impeller Manufacturer Technical Sheet
Minimum Basin Diameter 18" Manufacturer Technical Sheet
Cord Length 10 ft Heavy-Duty SJTW Manufacturer Technical Sheet

Engineering Limitations to Weigh

  • Do not exceed maximum pumping lift of 47.6 feet to avoid continuous motor thermal tripping.
  • Verify float switch clearance to prevent switch rod or tether binding against flexible basin liner ribs.

Frequently Asked Technical Questions

What is the actual discharge flow of the Zoeller M161-10FT at 10 feet of lift?
At 10 feet of Total Dynamic Head (standard 8-foot vertical wall lift plus pipe friction loss), the Zoeller M161-10FT delivers 3,300 GPH (approximately 55.0 GPM).
Can the Zoeller M161-10FT fit into a 12-inch sump basin?
The manufacturer specifies a minimum basin diameter of 18". Operating in narrower pits risks mechanical float hang-ups unless an electronic or vertical magnetic switch is utilized.
Does the Zoeller M161-10FT require a discharge weep hole?
Yes. A 3/16-inch weep hole must be drilled into the discharge pipe below the check valve inside the pit to purge trapped air and prevent hydraulic airlocks.

Technical Sources & Documentation

  1. Zoeller Technical Specification Sheet & Performance Curve (M161-10FT) — Zoeller Engineering Technical Documentation (Retrieved 2026). View primary source
  2. Hydraulic Institute ANSI/HI 14.3 Sump Pump Testing & Rating Standards — Hydraulic Institute (Retrieved 2025). View primary source