Zoeller 540 Flex Water-Powered Backup Sump Pump
- Water powered, no battery or electricity
- 20 gpm flow rate
- ¾ inch inlet, 1-½ inch discharge
- Horizontal or vertical installation
- Product only in the package
Last refreshed Sep 28, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A water-powered backup sump pump that needs no battery or electricity, meant for use when the main pump fails. It is a backup rather than a main pump, and the listing gives no supply pressure or lift height.
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ASIN: B085W7Z4DGModel: 540 FlexCategory: Sump Pumps
Overview
A sump pit with a failing primary pump gets a backup driven by water supply instead of a battery or mains power. It installs horizontally or vertically and connects through its inlet and discharge ports.
Running without batteries or electricity means it can work when the main pump has failed. The listing is silent on the minimum supply pressure and the lifting height, and those decide whether it clears a given house.
Who it's for
A homeowner who already has a main sump pump and wants a backup that does not depend on electricity or a battery bank. Anyone who needs a primary pump, or has no usable water supply at the pit, should look elsewhere.
Pros and cons
- No battery or electricity required
- Mounts horizontally or vertically
- Stated flow rate
- Backup only, not a main pump
- Supply pressure need not listed
- No lift height given
- No fittings listed in the package
Performance notes
Because it runs on water instead of electricity, its output depends on the water supply feeding it, not on the grid. The listed flow rate describes the pump itself, and the port sizes set the pipe it connects to. Lift height is not given.
Specifications
| Brand | Zoeller |
|---|---|
| Model | 540 Flex |
| Dimensions & fit | |
| Item Dimensions L X W X H | 5.6"L x 13.8"W x 15.5"H |
| Discharge size | 1-½ inch |
| Inlet size | ¾ inch |
| Capacity & performance | |
| Flow Rate | 20 gpmlower than 91% of 23 sump pumps |
| Power & efficiency | |
| Power Source | Water Powered |
| Construction & materials | |
| Material Type | Plastic |
| Color | Black |
| Compatibility & installation | |
| Installation | Horizontal or vertical |
| Included components | |
| Included Components | Product Only |
| Unit Count | 1 Count |
| Other details | |
| Product Style | Sump Pump |
Closest rivals on specs
WAYNE WaterBUG Submersible Utility Pump 1/6 HP- Flow Rate 20 vs 23 gpm (-13%)
Basepump RB750 Water-Powered Backup Sump Pump- Flow Rate 20 vs 15 gpm (+33%)
Frequently asked questions
Is the Zoeller 540 Flex a primary sump pump?
No. The listing describes it as a backup system for use during sump pump failure.
Does the listing say how high the Zoeller 540 Flex lifts water?
No. It gives a flow rate and port sizes but no lifting height or supply pressure.