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Quick answer from a licensed plumber: Buy a grinder only if the waste must travel far, climb high or feed a pressurized sewer main. For short runs, the makers point you to an ejector, and Zoeller says never to use a grinder upstream of a septic tank. For a new basement bathroom, the Liberty ProVore 380 system is our pick. On a 230 V circuit, the pump-only Liberty PRG102A matches that system’s 50 ft shut-off head, and for an existing 18-inch basin on 115 V, the Zoeller Shark M803.
Our pick for a basement bathroom that needs a grinder: the Liberty ProVore 380 system, with basin, pump and floats assembled at the factory. Check the Liberty ProVore 380 on Amazon
A grinder pump chops sewage into a fine slurry so it can be pumped through small pipe over a long distance, up a steep lift or into a pressurized sewer main. Zoeller’s own guidance is that for short runs into a gravity sewer or septic tank, a regular sewage ejector is the right pump. So the first job is deciding whether you need a grinder at all. This guide compares four grinders from the makers’ documents. For the everyday basement case, see our sewage ejector pump guide and upflush toilet guide.
Grinder Pumps Compared
| Pump | HP / volts | Discharge | Flow at 20 ft of head | Flow at 30 ft | Shut-off head |
|---|---|---|---|---|---|
| Liberty ProVore 380 system | 1 / 115 V | 2 in. | curve only | 28 GPM | 50 ft |
| Liberty PRG102A | 1 / 230 V | 2 in. | curve only | 28 GPM | 50 ft |
| Zoeller Shark M803 | 1/2 / 115 V | 1-1/4 in. | 22 GPM | 9 GPM | 35 ft |
| Zoeller M802 | 1/2 / 115 V | 2 in. | 27 GPM | 0 (shut-off is 29.5 ft) | 29.5 ft |
Figures from the Zoeller FM2882 and FM3575 data sheets and Liberty’s PRG-Series specification, read on September 29, 2026. Liberty prints only the 30 ft point in text; the rest is on its curve. None of these pumps was sold by Amazon or by the maker on Amazon when we checked. Every linked listing is a third-party seller offering the named maker’s model, so read the seller’s return terms before you order.
Do You Actually Need a Grinder?
Long runs, high lift or a pressure main
Zoeller says a grinder is required when waste must travel long distances, climb a high vertical lift or enter a pressurized sewer main. Its rule of thumb is to switch to a grinder when total dynamic head passes what a standard ejector can do, “usually about 20 to 25 feet.” Plumber’s note, not from a maker: if your home is on a municipal low-pressure sewer, the utility may own or specify the grinder station, so call it before you replace anything.
Septic tanks: the makers’ warning
Zoeller says to never install a grinder upstream of a septic tank. The slurry stays suspended in the tank and gets pushed out to the drain field, which can lead to sewage surfacing in the yard or backing up into the house. Zoeller’s septic article says the preferred fix is to let the house drain to the tank by gravity and pump the effluent to the drain field instead. See our septic tank riser guide for access to the tank.
Grinders cost more to keep
Zoeller says ejectors generally cost less to own because they have fewer moving parts and no blades to dull. Grinder cutters can jam or dull from things that should not be flushed.
Liberty Pumps ProVore 380 Grinder System (P382XPRG101)
1 HP PRG101 grinder, 115 V, 12 A · 24 x 24 in. polyethylene basin, 41 gallons · 4 in. no-hub inlet, 2 in. discharge · 16-bolt cover, IAPMO listed, passes a 10 ft stack test (Liberty) · QuickTree removable float switches · 10 ft cord · 87 lb · 3-year limited warranty
Liberty sells the ProVore 380 fully assembled for basement bathroom additions: a sealed 41-gallon basin with the PRG101 grinder, floats and cover already in place. Liberty’s PRG-Series specification gives the pump a shut-off head of 50 feet and 28 GPM at 30 feet of total dynamic head, and says it can pump slurry through pipelines as small as 1.25 inches. Liberty says the system can sit above or below floor level; if the top of the basin is below grade you need its access riser, and the maximum burial depth is 18 inches.
Liberty’s documents do not agree on pipe size. The system manual says ProVore discharge sizes may be reduced to 1-1/4 inches, with a note to consult Liberty. The PRG pump manual says not to reduce the discharge below the pump outlet size, and its warranty does not apply “if the pump discharge has been reduced in size.” Plan on a full 2-inch line unless Liberty confirms a smaller one for your run in writing. The sales sheet lists the high-water alarm as a factory option (an “/A2” suffix), so do not count on one with the base P382XPRG101. Liberty says an alarm must be on a separate electrical circuit. The linked listing is sold by The Plumbing Mall, a third-party seller.
- Factory-assembled basin, pump and floats, per Liberty
- 50 ft shut-off head and 28 GPM at 30 ft, per Liberty’s specification
- QuickTree floats come out without pulling the pump, per Liberty
- Basin is IAPMO listed and passes a 10 ft stack test, per Liberty
- Sold by a third-party seller (The Plumbing Mall), not Amazon
- Liberty’s manuals disagree on reducing the discharge to 1-1/4 in.
- High-water alarm is a separate order option on the sales sheet
- Draws 12 A at 115 V; Liberty wants the receptacle on a 20 A breaker
Verdict: The pick for a new basement bathroom where the waste has to travel far or climb high. You get the basin, pump and floats as one listed package.
Liberty Pumps ProVore PRG102A Grinder Pump
1 HP · 230 V, 6 A · automatic wide-angle float with piggyback plug · 2 in. NPT discharge · 10 ft cord · 58 lb · shut-off head 50 ft, 28 GPM at 30 ft (Liberty) · 140°F intermittent, 104°F continuous · 3-year limited warranty
The PRG102A is the pump-only, 230-volt version of the same ProVore grinder. Liberty says it shreds “feminine products, rags, towels and wipes” that can jam a solids-handling pump, and that PRG pumps can replace its LE40 and LE50-Series pumps in 2-inch systems. It adds that you should consult the factory with the actual head before doing that. For a new basin, Liberty’s manual calls for at least 18 inches across and 24 inches deep, sealed and vented to code.
Liberty’s 230-volt warnings matter here. On a 208/230 V pump, one side of the line is always hot whether the float is on or off, so Liberty says to install a double-pole disconnect near the pump. It also says to run the pump without its float only from the breaker or panel disconnect. It wants licensed electrical personnel present the first time the breaker is turned on. The 115-volt PRG101A listing showed only 3 in stock when we checked, so we did not link it. The PRG102A listing is sold by Big Frog Supply, a third-party seller.
- Ties the ProVore 380 for the highest shut-off head here: 50 ft (Liberty)
- Draws 6 A at 230 V, per Liberty
- Piggyback plug lets you run it from the breaker if the float fails, per Liberty
- Liberty lists it as a replacement for LE40 and LE50 pumps in 2 in. systems, after a factory check
- Needs a 230 V circuit and a double-pole disconnect, per Liberty
- Sold by a third-party seller (Big Frog Supply), not Amazon
- Pump only: basin, check valve, vent and alarm are separate
- Warranty is void if the discharge is reduced in size, per Liberty
Verdict: The pick when you have a 230 V circuit, or can add one, and want the ProVore’s 50 ft shut-off head from a pump you set in your own basin.
Zoeller Shark M803 Grinder Pump
1/2 HP · 115 V, 7.0 A · automatic, integral float switch (on 13 in., off 5-3/4 in.) · 1-1/4 in. NPT discharge · 15 ft cord · cast iron, 65 lb · 440C stainless cutter and plate · shut-off head 35 ft · 3-year limited warranty
The M803 is Zoeller’s half-horsepower Shark with the float switch built on, so it needs no outside control. Zoeller recommends a pit 18 inches or larger across. Zoeller’s table gives 35 GPM at 5 feet of head, 22 at 20 feet and 9 at 30 feet, and it shuts off at 35 feet. The same data sheet covers the 3/4 HP 805 (45 ft shut-off) and 1 HP 807 (55 ft). Their Amazon listings showed 3 or fewer in stock when we checked. The nonautomatic N803 is the same pump without the switch. Zoeller says it needs a piggyback float switch or a control panel.
Zoeller’s Shark instructions open with a plain line: “Zoeller does not recommend using grinder pumps in any part of a septic system.” They call for a grounded, GFCI-protected receptacle within reach of the cord and no extension cord, and they recommend a separate branch circuit. Unplug the pump before you handle it, and wait 2-1/2 hours after disconnecting before service because the oil inside is hot and under pressure. The Shark warranty runs three years from the date of manufacture, not purchase, and excludes damage from things like sand, hydrocarbons and wash towels. The M803 listing is sold by NYDIRECT and the N803 by Faucets and More, both third-party sellers.
- Built-in float, no separate control needed (Zoeller)
- Zoeller publishes a full flow table at 5 to 50 ft of head
- 1-1/4 in. discharge, the small line grinders are made for
- Cast iron body with a 440C stainless cutter, per Zoeller
- Flow falls to 9 GPM at 30 ft of head (Zoeller table)
- Warranty counts from the date of manufacture, per the Shark manual
- Sold by third-party sellers, and the M803 listing showed only a few in stock
- Zoeller does not recommend it anywhere in a septic system
Verdict: The pick for a 115 V circuit and an existing 18-inch basin, where your total head stays under about 30 feet.
Not linked: Zoeller N803 (needs a float switch) — on 10/3/2026 the Amazon listing was sold by a third-party seller, not by Amazon or the maker. We re-check listings every week.
Zoeller M802 Grinder Pump
1/2 HP · 115 V, 9.6 A · automatic snap-action switch (on 10 in., off 4 in.) · 2 in. NPT discharge · 9 ft cord with LED plug · 25.3 lb · shut-off head 29.5 ft · 48 GPM at 5 ft (Zoeller) · 3-year limited warranty from purchase
Zoeller calls the 802 “an economical upgrade from a traditional sewage pump to a grinder pump.” Its data sheet gives 48 GPM at 5 feet of head, 35 at 15, 27 at 20 and 17 at 25, and it shuts off at 29.5 feet. That is more flow at low head than the Shark M803 (35 GPM at 5 feet) and the least lift of any pump here. It fits a short run where you want solids ground up, not a long pressure line. The LED plug shows at a glance that the pump has power.
Zoeller’s own documents disagree in places. The product page says the motor is shaded-pole; the data sheet says permanent split capacitor. The M802 instructions say the receptacle “may be protected” by a GFCI, while the Shark instructions call for a GFCI-protected receptacle. The M802 warranty is three years from purchase with proof of purchase. It excludes damage from “wash towels or feminine sanitary products,” even though the same sheet says the pump grinds reasonable quantities of sanitary napkins. Treat the warranty line as the rule. The M802 sheet has no septic line, but Zoeller’s 2026 article says never to put a grinder upstream of a septic tank. The listing is sold by KART IT, a third-party seller.
- More low-head flow than the M803: 48 vs 35 GPM at 5 ft (Zoeller)
- 2 in. discharge and a built-in switch, per Zoeller
- LED plug shows the pump has power
- Warranty counts from the purchase date, with proof of purchase
- Least lift here: shuts off at 29.5 ft (Zoeller)
- Warranty excludes damage from feminine sanitary products and wash towels
- Zoeller’s pages disagree on motor type and GFCI wording
- Sold by a third-party seller (KART IT), not Amazon
Verdict: The pick for a short, low-lift run where an ejector keeps clogging and you want the solids ground. Look elsewhere if your head is near 30 feet.
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Before You Buy
- Work out your total dynamic head. Measure from the bottom of the pit to the highest point of the discharge, then add friction for every foot of pipe and every fitting. Read that number against the maker’s curve, not the horsepower on the box.
- Find out where the line goes. Into a septic tank: Zoeller says no grinder. Into a pressurized main: Zoeller says a grinder is required. Into a gravity sewer on a short run: an ejector usually does it.
- Match the circuit. The Liberty 380, Zoeller M803 and M802 run on 115 V; the PRG102A needs 230 V and a double-pole disconnect, per Liberty. Liberty says each pump needs its own properly fused, grounded branch circuit.
- Size the basin. Liberty calls for at least 18 in. across and 24 in. deep, sealed and vented; Zoeller recommends a pit 18 in. or larger. Local code may require more.
- Keep the receipt. Liberty wants a dated sales receipt with the model and serial number, and the Zoeller M802 warranty requires proof of purchase. With third-party sellers, save the invoice.
Install and Safety Notes
- Power off first. Both makers say to disconnect the pump from power before handling it. For flooded conditions, Zoeller says to have the electric company or a licensed electrician disconnect service before you pull the pump. Liberty says not to enter water deeper than your protective gear.
- Code, permit and a licensed plumber. Zoeller says every installation must comply with all applicable electrical and plumbing codes, and Liberty says to vent the basin to local code. Plumber’s note, not from a maker: a sewage basin, its discharge and its vent normally need a plumbing permit and inspection, so have a licensed plumber pull the permit and do that part of the job.
- Licensed electrician. Zoeller says the pump’s circuits should be installed and serviced only by a qualified, licensed electrician. Liberty says the power supply for a below-grade install must be at least 4 ft above the floor. Neither allows extension cords.
- GFCI. The Zoeller Shark instructions call for a GFCI-protected receptacle; the M802 instructions say the receptacle “may be protected.” The Liberty PRG manual lists a tripped GFCI only as a troubleshooting cause. Ask your electrician what local code requires, and remember a tripped GFCI stops the pump.
- Gas and venting. Liberty warns that sewage basins can hold poisonous and explosive gases. It says never to enter a basin after use, and to vent the basin to local code. Zoeller calls for gas-tight seals and a vent pipe to the atmosphere. If you smell sewer gas in the house, see sewer smell in the house.
- Check valve and valves. Liberty requires a check valve after the union, then a gate or ball valve. With a check valve, Zoeller says to drill a 3/16 in. vent hole in the discharge below the check valve and the basin cover, and keep it clear. See check valve basics.
- Alarm. Liberty cites the Uniform Plumbing Code as requiring an audio and visual alarm on sewage systems, and says an alarm must be on a separate circuit. See our sump pump alarm guide, which covers Liberty’s ALM-2.
- Cutters and heat. Liberty says to wear hand protection because the cutters are extremely sharp. Zoeller says not to turn the cutter with your fingers and to wait 2-1/2 hours after disconnecting before service.
FAQ
Do I need a grinder pump or an ejector pump for a basement bathroom?
Most basement bathrooms need an ejector. Zoeller says a grinder is required when waste must travel long distances, climb a high lift or push into a pressurized sewer main. For short runs into a gravity sewer or septic tank, Zoeller says a standard sewage ejector is the right choice. See our sewage ejector pump guide.
Can a grinder pump go into a septic tank?
Zoeller says no. Its Shark instructions say it “does not recommend using grinder pumps in any part of a septic system.” Its 2026 article says to never install one upstream of a septic tank, because the fine slurry stays suspended and gets pushed into the drain field. Liberty’s PRG manual lists “septic tank effluent” among its uses, which is liquid leaving a tank, not raw sewage going in. Follow the stricter rule and ask your septic designer.
What size discharge pipe does a grinder pump need?
Follow the pump’s outlet unless the maker approves a change. The Zoeller Shark has a 1-1/4 in. outlet; the Zoeller 802 and Liberty ProVore have 2 in. outlets. Liberty’s manuals conflict: one allows reducing ProVore discharge to 1-1/4 in., and the PRG manual forbids reducing it and voids the warranty if you do. Keep the full size unless Liberty confirms otherwise.
How far can a grinder pump push sewage?
It depends on total dynamic head, not distance alone. Zoeller counts vertical lift plus friction from every foot of pipe and fitting. Its example is a 15 ft lift followed by 500 ft of pipe and elbows, which can push total head past 30 ft. Maker shut-off heads for the pumps here run from 29.5 ft (Zoeller 802) to 50 ft (Liberty PRG). Pick a pump whose curve still gives flow at your head.
Can a grinder pump handle wipes and feminine products?
The makers say their grinders can, but their warranties are narrower. Liberty says the PRG shreds “feminine products, rags, towels and wipes.” Zoeller says its grinders handle reasonable quantities of such items, yet the M802 warranty excludes damage from wash towels or feminine sanitary products. Keep them out of the line anyway.
Why Trust Plumbing Picks
Plumbing Picks is written by a licensed Georgia journeyman plumber. Every spec here comes from the maker documents listed below or the Amazon listings we link; nothing comes from hands-on testing. On September 29, 2026, no Amazon-sold or maker-sold listing existed for these grinders, so each link goes to a third-party seller offering the named model (The Plumbing Mall, Big Frog Supply, NYDIRECT, Faucets and More and KART IT), in stock when we checked. If you buy through a link we may earn a commission at no extra cost to you. Nobody pays to be included here. More on who writes this and how we pick.
Sources
- Zoeller: Sewage Pump vs. Grinder Pump, Which Do You Need?, Grinder and Septic Systems, Pumping to Septic Tanks
- Zoeller: Shark 803/805/807 technical data sheet FM2882, installation and service instructions FM2903, M803 product page, N803 product page
- Zoeller: Model 802 technical data sheet FM3575, M802 installation instructions FM3539, M802 sales sheet FM3498, Model 802 product page
- Liberty Pumps: ProVore PRG-Series page, PRG-Series sales sheet, PRG-Series engineering specifications, PRG-Series installation manual 2399000E (includes the warranty)
- Liberty Pumps: ProVore 380 page, ProVore 380 sales sheet, Pro-Series and ProVore system installation manual 7225000
- Amazon listings for the Liberty ProVore 380 (P382XPRG101), Liberty PRG102A, Zoeller M803 and N803, and Zoeller M802 (linked above)
Bottom Line
Decide first whether you need a grinder. A long run, high lift or pressure main says yes; a septic tank says no, per Zoeller. Then size the pump from total dynamic head and the maker’s curve. The Liberty ProVore 380 is the complete system to buy for a basement bathroom, the PRG102A is the pump-only choice on 230 V with the same 50 ft shut-off head, and the Zoeller M803 suits an 18-inch basin on 115 V. Have a licensed plumber and a licensed electrician do the work under a permit, vent the basin and add an alarm.