Best for small pits in sump pumps
A one-piece cast-iron 1/3 HP pump whose vertical magnetic float has no switch arm or rubber boot to wear, and it fits a pit as narrow as 10 in.
Our score: 7.8/10 out of 10Researched, not lab-tested
- Motor
- 0.33 HP
- Switch
- Vertical magnetic float
- Maximum lift
- 23 ft
- Minimum pit width
- 10 in
Is it right for you?
Pros
- Vertical magnetic float switch: no switch arm or rubber boot
- Fits a sump pit as small as 10 in across
- One-piece cast-iron body; quick-connect cord replaceable
- Shut-off head 23 ft; up to 44 GPM at 5 ft
- cCSAus certified for Canada and the US
Cons
- No flow figure at 10 ft published, only a curve
- 10 ft cord as standard; 25 ft means the separate 257-2 model
- Sold mostly through plumbing distributors, so fewer stores carry it
- 1/3 HP: a very wet pit may need a 1/2 HP pump
- Best for
- Replacing a pump in a narrow or crowded pit, or anyone who wants a switch with fewer seals to fail.
- Not for
- Buyers who want a published flow at their lift to compare, or very wet pits that need 1/2 HP or more.
Our verdict
The Liberty 257 is the pump for a narrow pit. Its vertical magnetic float moves a magnet rather than a switch arm, so there is no rubber boot to crack and let water into the switch, and Liberty’s brochure lists a minimum pit diameter of 10 in, against 14 in for its wide-angle-float models. The body is one-piece cast iron, the 1/3 HP motor is a permanent split capacitor type with upper and lower ball bearings, and the pump is cCSAus certified, with a three-year warranty.
The catch is comparison. Liberty’s engineering specification gives a 23 ft shut-off head and 44 GPM at 5 ft, but no figure at 10 ft, so we leave that blank rather than read it off a curve. If you need a known flow at a typical lift, the Zoeller M53 publishes one. Liberty sells mainly through plumbing distributors; the 257 is on sale in both Canada and the US.
Installing and looking after it
The quick-connect cord can be replaced without opening the motor, and the standard cord is 10 ft (the 257-2 has 25 ft). Liberty rates it for water up to 104 °F continuously and 140 °F intermittently, with a 1-1/2 in discharge that passes 1/2 in solids; Liberty’s 1-1/2 in quiet check valve (QCV150) suits the outlet. Follow the installation manual in the box for the check valve, vent hole and outlet.
Safety: Unplug the pump before you reach into the pit. If the basement is already flooded, stay out of the water while anything electrical could be live and ask your electric utility to cut the power; our guide to the first hours after a basement floods goes step by step.
Specs
Liberty Pumps 257 1/3 HP Cast-Iron Sump Pump with Vertical Magnetic Float
Pump
| Motor | 0.33 HP |
|---|---|
| Maximum lift | 23 ft |
| Switch | Vertical magnetic float |
| Minimum pit width | 10 in |
| Cord length | 10 ft |
| Housing | Cast iron |
| Discharge | 1-1/2 in |
Other details
| Warranty | 3 years |
|---|---|
| Works in an outage | No |
| Alarm | No |
| Safety listing | cCSAus |
Maker’s figures, checked 4 Nov 2026.
Liberty 257 questions
What size sump pit does the Liberty 257 need?
Liberty’s brochure gives a minimum pit diameter of 10 in for the 257 with its vertical magnetic float. Its wide-angle-float models need 14 in.
Why choose a magnetic float switch?
The float moves a magnet past a sealed switch instead of working a switch arm through a rubber boot, so there is no boot to crack and let water into the switch.
How much water does the Liberty 257 pump?
Liberty publishes a maximum of 44 GPM at 5 ft and a shut-off head of 23 ft. It doesn’t print a figure at 10 ft, only a curve, so we don’t give one.
