How to Replace and Plumb a Home Grinder Pump

grinder pump components with messy mud on them
  • 2-4 hours
  • Intermediate
  • 700-7,000
What You'll Need
2 Screwdrivers (Phillips and flathead)
Adjustable wrench
New grinder pump
Wire twister
What You'll Need
2 Screwdrivers (Phillips and flathead)
Adjustable wrench
New grinder pump
Wire twister

Like a garbage disposal, a home grinder pump grinds waste before it gets pumped out into the sewer system. This is a pretty essential function for waste removal, so clearly, it's important to know how to replace and plumb home grinder pumps.

What Is a Home Grinder Pump?

A septic tank system makes use of several pumps, including a grinder pump, to move waste through the system efficiently. The grinder pump grinds all the waste and crushes it into smaller pieces before discharging the wastewater to a public sewer system.

Usually, the grinder pump is outside of the house, buried in the ground.

The septic tank has a wastewater holding compartment that fills with wastewater from the drains in your home. Once the tank gets full, the grinder pump will activate to grind up the waste into smaller pieces.

When the pump stops working, however, the waste won't get grinded up...and that's no good.

Septic tank systems are equipped with an alarm that alerts you about any failure in the drainage system, such as blockage or insufficient flow of wastewater. The alarm will also sound when a grinder pump fails, and the flow of water is disturbed.

If any of the pumps in a septic tank system break down, the septic tank system is not functional. The pump should be replaced without any delay to prohibit overflow or drainage problems.

The last thing you want is a clogged, backed up septic system that is allowing wastewater into your home. Because when the waste can't exit your property through the sewer system...well, you can connect the dots.

You need your grinder pump system to be functioning properly. Grinder pumps can malfunction for lots of different reasons, and when they do, you need to fix the problem right away.

When your pump fails to respond to grinder pump repair options, you need to replace the pump with a new one.

grinder pump case

Things You'll Need to Plumb a Home Grinder

Gather up the materials and tools you know you'll need to plumb or replace a grinder pump to make the job go more efficiently and easily. You don’t want to stop in the middle of the job because you don’t have the right tools handy.

New Grinder Pump

Obtain a new grinder pump at any home improvement store or plumbing supply shop. You need a pump that is the same size as your existing pump.

It’s much easier if the new pump has a similar configuration to your old grinder pump, so you can connect the electricity and water to the pump fairly quickly.


Have a couple of screwdrivers handy, both Phillips head and flathead. Most DIYers will already have these standard tools.

If not, pick up a screwdriver at any home improvement store. You will find many more uses for this standard tool.

Wire Twister

A wire twister is a small tool used to wrap and manipulate wires. This is used for electrical wire and other small wires.

You will use this to disconnect and later reconnect the electricity to the pump. It’s not advisable to handle electrical wires with your bare hands, so be sure to get this tool.

Pipe Sealant

Use pipe sealant when connecting the new pump to prevent leaks. You will use this sealant around all pipe connections.

plumber's tape on pipe fitting

Adjustable Wrench

An adjustable wrench is necessary for many home improvement and DIY tasks. Adjustable wrenches can be used to adjust many different sizes of nuts and bolts.

How to Replace a Home Grinder Pump

If your grinder pump stops working and needs to be replaced, you don't have to rely on someone else to do it. Replacing your home grinder pump is doable with just a few tools.

Get the new pump, the tools, and the materials you need, and you will have everything you need for grinder pump installation, so you can get your entire septic tank system working properly again.

Check Your Pump

Slow drainage, clogged toilets, and general waste elimination sluggishness throughout the house is a clear indication that some part of your septic tank system isn't working.

The pump grinder is one of the first things you’ll check when you’re troubleshooting your waste problems.

Stop using water and stop flushing toilets. If waste isn't being properly eliminated, it will ultimately back up into the house unless you stop adding to the problem.

The easiest way to stop adding water to the septic tank is to turn the main shut-off valve to the house, which prevents any and all water from coming out of the faucets or into the toilets. However, you’ll also need to tell everyone in the house not to flush the toilet because this will add more wastewater to your already-strained septic tank.

Check the electricity first by making sure the pump is plugged in and if it is not, unplug it and test the plug using another device to ensure that the grinder pump is getting electricity. If the electricity seems to be working well, you have an entirely different grinding pump problem.

Next, try to manually trigger the float switch on the pump with a coat hanger by lowering the hook inside the pump. Some grinder pumps do not have a float switch but if yours does, test it and then try to clean the switch with a hose to remove any buildup or debris that may be causing the float switch to malfunction.

Make sure the grinder pump is turned off, and then check for a clog, particularly around the area where the waste is ground up. Do this with extreme caution.

If you can't repair the grinder pump problem, it will need to be replaced.

Buy a New Pump

Check the specs of the present grinder pump in your home because you'll need a new pump that matches the measurements and specs of your existing pump. Write down everything carefully and double-check everything you take down so you can be sure you get a pump in the right size.

You may also be able to take pictures of the specs on the pump, which makes it easier.

Remove the Bad Pump

Switch off the electrical lines to the pump from the supply panel. Remove all electrical wiring connected to the broken pump.

These electrical connections need to be removed to take out the broken pump and install a new pump. Note what is attached and where and take pictures so you can hook the electricity up to the new pump properly.

You don’t want to disconnect the electricity without knowing how to get it reconnected again, so pay attention to what you’re doing and take lots of pictures as a handy visual aid.

Turn off the water supply line. Otherwise, wastewater will continue to fill up the septic tank.

Many pumps have an automatic thermal overload system, which may start an overheated pump unexpectedly. Carefully remove the cover with the ventilation pipe of your sewage basin.

All liquid and debris should be removed. Once the basin is clean, disconnect the discharge piping from the pump’s discharge connection.

Remove the pipe connections to the pump at its inlet and outlet. Some water may leak out of the pipes after you disconnect them.

Lift out the broken pump from the sump pit. You might be able to recycle this, so don’t throw it away.

new and old pump near dirty pipes

Install the New Pump

How do you install a residential grinder pump? Once you've removed the old pump, it's a simple matter of placing the new pump in the old one's place.

If your pump doesn't come with a lift-out system, it’s advisable to install one for easy removal during maintenance or repair without disturbing the discharge piping. Now is the time to install the system, so take this opportunity and make things easier on yourself in the future.

The lift-out system should be located opposite the waste entry opening, so don’t block this area. Rails should be properly anchored to the basin’s floor.

Fit the pump to the lift-out system adapters. Lower the pump into the basin.

Connect the supply line and the electricity to the new pump. Next, switch on the power supply from the panel and turn on the water supply.

The pump must be connected to a properly grounded receptacle. Ensure that the switch float alarms are operating freely and won’t contact the piping.

Connect the discharge piping to the pump’s connection. Use pipe sealant if necessary.

The discharge piping shouldn’t be smaller than the pump’s discharge diameter.

Go flush the toilet and run some water and see if the pump is now working properly. If it’s doing its job, the water will go into the tank, and the waste will start to be ground up by the grinder pump.

Check for leaks. Once the grinder pump system is working, the system is ready for automatic operation again.

Replace the basin cover and lock it, if applicable. If you’re not sure that everything is connected properly, you can get always ask an electrician to check if you’ve wired everything properly.

Replacing and Plumbing a New Grinder Pump

The way you install a grinder pump depends on the type of pump you have. Famiarilize yourself with your pump by troubleshooting it and find out how it should be functioning.

When grinder pump maintenance and basic repair don’t work, your best option is to replace the grinder pump entirely so that you are an effective and efficient grinder pump system that is functioning again.

Once your new pump is in place, use regular maintenance to keep it in good working order so you can avoid replacing your new pump for as long as possible.

When you know how to do this DIY project, a malfunctioning grinder pump will never be a big problem for you again. That's good news because there are few things worse than a septic system that isn't effectively removing waste from your home.

Grinder Pump FAQ

Can you use a liquid plumber for a grinder pump?

Want to know how to use a liquid plumber for a grinder pump? Don't!

Chemical drain cleaners can cause a great deal of damage to your pipes and to drainage systems, anything connected to the drainage coming from your home. If you want to know the best way to use them, it’s by not using them at all.

Drain cleaners are formulated to eat away at debris clogging your pipes, but these formulas are also capable of eating through your pipes, too. This can cause even more damage to your home's drainage.

Many plumbers advise against using chemical drain cleaners of any kind because of the damage they can cause to your pipes and to your plumbing.

How long does it take to replace a grinder pump?

The length of time to replace a grinder pump depends on how much wiring and piping you have to do to disconnect from the old grinder pump and reconnect to the new one. This is what will take the longest amount of time throughout the installation.

Most of the time, this is a job that can be completed in just a few hours. If there is a delay because you have to order a grinder pump or a pump part, you could be waiting for a month or more.

Obviously, you'll need a temporary sewage solution if this is the case.

How much does a grinder pump cost?

What is the cost of a grinder pump replacement? Remember, you will not only pay for the new pump but for the materials and tools you need to use in order to swap it out.

The cost of a grinder pump varies depending on the size and the features of the pump, but you can expect to pay anywhere from $150 to $1,000 for the pump alone. The vast difference in size creates a vast difference in price.

Further Reading

4 Common Septic System Problems and How to Avoid Them

How to Install a Grinder Pump System

Troubleshooting Septic Tank Problems

Troubleshooting a Sewer Grinder Pump