Grinder Pump Not Working – Helpful Troubleshooting Guide

When your grinder pump stops working, that could mean some serious problems for your home septic system. The first thing that you should do is STOP using water in your home. Do not flush the toilets, run the dishwater, use a washing machine, or have a shower because this could cause the septic tank to fill up and send wastewater back up through the pipes and into your home.

How Does a Grinder Pump Work?

The grinder pump is a big part of the sewer system for many homes. In most cases, a grinder pump sits in a tank that is located on the outside of the home and buried underground in a convenient section on the homeowner’s property. Inside the tank is a wastewater holding compartment that fills up with the wastewater produced in your home from things like the toilet, shower, washing machine, sinks, dishwasher, etc.

Once the holding compartment reaches a pre-set level of wastewater, the grinder pump will automatically turn on. At the bottom of the grinder pump is an impellor that will spin, which sucks in the wastewater and anything else that has made its way into the holding tank, such as toilet paper and human waste.

The grinder pump will run for a few minutes, while the cutting blades grind the waste into tiny particles in the same way that garbage disposals do. The pump then forces the wastewater out of the tank and into a pressurized city sewer main. Once the level of wastewater in the tank has emptied, the grinder pump will automatically shut off.

Why Is My Septic Pump Not Working?

As with any mechanical device found around your home, the grinder pump can also experience malfunctions and breakdowns. Below are five of the more common issues that you might have with your grinder pump.


Check that the outlet that is powering the grinder pump is getting power. If you can, try unplugging the grinder pump from the outlet and plug in a light or another electrical device to test that there is power. If that equipment turns on, then you know the problem is with the pump, but if the device does not turn on, then there is a power connection problem. Check both the fuse box in your home, as well as the one inside of septic alarm panel, to see if the fuse was tripped.

Float Switch

If your ejector pump has a float switch, try stretching out a coat hanger and lowering the hook side down into the tank. Hook around the float switch and try to get the pump to start up. If the pump doesn’t start, you might need a new pump or a new float switch.

Before buying a new pump, you could try purchasing a piggyback switch, which will bypass the onboard switch in the pump. A good piggyback float switch on Amazon will cost under $25 (click here for current price).

Now, if you lift the float switch using the coat hanger and the pump does turn on, then this means the float isn’t working properly. A common reason for this is due to debris on the float weighing it down, or the float rod is impeding its movement in some way. Try taking a garden hose to clean the float and the rod off and then filling the tank with water to see if the float turns on properly.

If the float is still not properly working after you’ve cleaned it, it could be possible that water has gotten into the float, causing it to become heavy. In which case you will need to replace the float.


One of the most common reasons for a pump to stop working is because of a clog in the impeller. Clogs are usually caused by flushing items down the toilet that is not supposed to be flushed. For example, although disposable baby wipes claim that they are okay to be flushed down the toilet if your sewer system relays on a septic pump or a grinder pump to remove waste, then you should never flush these down your toilet because they will clog the pump.

Clogs are not good for a grinder pump. What happens when your pump begins to clog is that the start capacitor in the pump will have to work harder, which then causes the motor to heat up and eventually burn out. Nine times out of a ten, when your pump is clogged, you might have to replace the whole thing.

Before checking for a clog, ensure that the power is turned off, and double-check with a voltmeter to make sure.


No matter how hard you try, grease will sometimes still make its way through your pipes and into the holding tank, to create a blockage within the pump. Not only grease but dirt, coffee grounds, baby powder, pancake mix, etc. All of these could cause the pump to jam up and fail over time.

Frozen Pump

Grinder pumps are buried below the frost level underground to prevent them from freezing during the winter. But what sometimes happens is that a pump doesn’t get buried deep enough, and when that happens, the wastewater inside of the pump will freeze and cause it to stop working. To fix this problem, you will need to bury the tank and pump deeper into the ground.

What Happens When a Grinder Pump Fails?

When the grinder pump fails, an alarm will be triggered to go off on your septic systems alarm panel. The red light on the top of the panel will turn on, followed by a beeping noise that is meant to get your attention. There’s normally a silence button on the panel that you can use to turn the beeping noise off, but the red light on the top of the panel will stay lit.

Another thing that can happen if your grinder pump fails is that your tank could overflow into your backyard, or back up into your home through sinks and toilets.

Most of the time, the reason why a grinder pump would fail is because of what got flushed down the toilet or sink. The only thing that you should be flushing down the toilet is human waste and toilet paper. Anything else can cause the pump to fail and stop working.

Avoid flushing these everyday items

    • Paper towels
    • Feminine hygiene products
    • Disposable diapers
    • Condoms
    • Diapers
    • Baby wipes
    • Grease or fat
    • Coffee grounds
    • Dental floss
    • Strong chemicals
    • Plastics
    • Metals
    • Rubber gloves
    • Q-tips
    • Dirt/dust
    • Cat litter
    • Cotton swabs
    • Cigarettes or cigarette butts
    • Hair (people or pet)
    • Kleenex

Keep in mind that this list mentioned above is meant to give you an idea of what type of items should never be flushed down the drain or toilet and not a complete list.

What Does a Red Light On Grinder Pump Mean?

When the red light comes on, this is an indication that there is too much water in the pump tank. The red light should also be accompanied by a beeping sound to get your attention.

Generally the water in the tank will get too high if the float isn’t working properly, or the pump itself has stopped working because of a clog, or it’s time to be replaced.

Another common reason for a higher than normal water level is because of too much water getting put through the septic system. This can happen if the homeowner has had a lot of long showers or has done multiple loads of laundry. Heavy rainfalls could also cause the levels to rise if the rainwater can seep into the tank someplace.

Most septic systems have some type of timer installed that controls when the pump can run and pump wastewater to the drain field. The reason you would want to control how much wastewater is entered into the drain field is that too much wastewater could damage the drain field, and so the timer is designed to prevent that. Now, because the timer will only turn on a few times per day, the extra water being introduced into the holding tank would have nowhere to go, which will cause the level to rise higher then it should, triggering the red light to come on.

If your alarm is on, stop using water, stop flushing toilets and stop washing machines and dishwashers right away to help avoid a sewer backup.

Proper Grinder Pump Maintenance

As the homeowner, it is your responsibility to make sure that the septic system on your property is working correctly.

Pump maintenance

The grinder pump itself shouldn’t require any preventative maintenance, but if your grinder pump is using floats to sense the level of wastewater, then those floats are prone to grease build-up, which could affect how they operate. Toilet paper could also find its way onto a float and weight it down, preventing the pump from turning on when it should.

Once or twice a year, you can take a garden hose and clean off the floats.

The best thing that you can do for your pump is to make sure that you are only flushing human waste and toilet paper down the toilet. Anything else could block and damage your pump.

Tank Maintenance

Septic tanks will eventually fill up with sludge and will need to be pumped out. It is in your best interest to call a professional since they are properly trained to handle the waste and disposal. But when should you call them to pump the tank? The answer to that question is: It depends.

Let me explain why it depends.

In the tank, wastewater naturally separates into three different layers through both biological actives and retention. Those layers from top to bottom are; Scum, Effluent, and Sludge. If for a reason, your tank is not separating the waste into these layers then that means there is something wrong with your tank, and it’s not working as it should.  

Liquid effluent is the only thing that should be leaving the tank. Solids and grease are left trapped inside of the tank. Over time the sludge and scum begin to build up inside of the tank and will eventually need to be emptied.

You will need to pump the tank when the scum and sludge layers combined make up 25 to 33 percent of the liquid depth of the tank. By not pumping your tank, you will allow the sludge and grease layers to build up to an unhealthy amount, not to mention the tank will not function properly, allowing all of the wastewater to bypass the tank and enter your field system.

As a general rule, you should be emptying your septic tank once every two to four years. However, that does depend on usage and how many people are living in your household. Larger households will need to have the tank pumped more frequently than smaller households. For example, a family of seven might need to pump every two years, while a family of three might have to pump every four years.

There is a tool that you can purchase called a “Septic Core Sampler” that will allow you to take a cross-sectional view of the contents in the tank. The core sampler is available on Amazon for just under $120 (click for current price), but it can help save you money in the long run.

To have a company come out and pump your tank, it could cost anywhere from $250 and up. So it is nice to know when the tank needs to be pumped rather than guessing. I would recommend calling at least three different companies for quotes.

A septic tank should last between 25 to 40 years before needing to be replaced.

How Long Does a Grinder Pump Last?

Like any piece of equipment, the grinder pump will eventually stop working and will need to be replaced with a new one. The typical life expectancy for a grinder pump is between eight to ten years. With the proper maintenance and care, you could get fifteen years out of one.

Now, this depends on what you are flushing down the toilet and what type of dishwasher and washing machine detergent you are using. That’s right; washing detergents can affect the life of your pump. These types of things will slowly clog the pump and render it useless.

If you are not getting at least eight years out of your pump, you need to take a look at what you might be flushing down the drains. Another possibility is that your pump is not a suitable fit for the job. Perhaps the public sewer system is too far for the pump to go, or the tank is too large for the size of pump you are using. Consult with a professional to help you determine if the pump is a suitable size for you.

How Much Does It Cost To Replace a Grinder Pump?

Grinder pumps are not cheap. When shopping for a new grinder pump, the first thing that you are going to notice is the price tag. A good reliable residential grinder pump can end up costing you anywhere between $800 to $2500 depending on the make and model.  

It also depends on how far you need to pump the waste to get to the public sewer system, and if it has to be pumped uphill at all.  How much horsepower the pump needs plays an important role in how much it will cost.

Installation and labor is an additional cost, depending on who you hire for the job. If you are buying a replacement pump, this is something you could install yourself. The most important thing is to make sure that the new pump will be strong enough to do the job that you need it to do.

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