Zoeller 98-0001 M98 Flow Mate Submersible Sump Pump Review and M63, CDU1000, M267 Comparison

When recommending a quality AC sump pump to homeowners disappointed one too many times from budget box store sump pumps, we generally stick to one of two brands: Zoeller and Wayne. At the top of the rankings sits the Zoeller M267; this is the single best AC sump pump on the market in terms of maximum flow rates, grinding power, durability, and long-term reliability. However, as you spend less and less, you make more and more compromises; that’s just how the sump pump market works. At the $200-ish range, we typically recommend the Zoeller M63, Zoeller M57, or Wayne CDU1000. These pumps have been among the most reliable and best functioning AC sump pumps in our experience after the Zoeller M267. However, there’s another option at the $200 price range that we recommend with some reservation: the Zoeller 98-0001 M98 Flow-Mate Sump Pump. On paper, it’s one of the most powerful AC sump pumps on the market, but a number of premature failures has caused us to refrain from recommending it over the other pumps we’ve reviewed. If you get a good model, however, it works very well. Let’s take a closer look.

Key Features of the Zoeller M98 Sump Pump (60 Second Summary)

The Zoeller M98 sump pump is an automatic submersible sump pump designed for effluent (sewage) and dewatering (sump) work in sump pits, septic tanks, STEP systems, and low pressure pipe systems. It includes a 1/2 HP motor, a max flow rate of 4,320 gallons per hour, and features a 1 year warranty from installation date or 18 month warranty from manufacture date. It is 12 inches tall, 10-1/8 inches wide, and 8 inches deep.

The max head, or max pumping height, is 23 feet; the switch-on/switch-off heights are 3 inches and 9-1/2 inches respectively. There is a vertical float switch. It uses 4.7-9.4 amps and 115 or 230 volts; no battery backup is included. It weighs 39 pounds and includes a 15 foot power cord. Although it can pump up to 4,320 gallons per hour at 0 feet, it drops to 3,660 gph at 10 feet, 2,700 gph at 15 feet, and 1,500 gph at 20 feet. Shut-off occurs at 23 feet. The operational temperatures span 40-130 degrees Fahrenheit. The M98 is self-priming with full cast iron construction; the discharge size is 1-1/2″ NPT with a minimum required sump pit diameter of 15 inches.

How Does the Zoeller M98 Compare to the Zoeller M63, Wayne CDU1000, and Zoeller M267 Sump Pumps?

The Zoeller M98 features a stronger motor (1/2 vs .3 HP) than the M63, as well as a much faster max flow rate (4,320 gallons per hour vs 2,580 gph). However, the warranty is much shorter at 1 year in the M98 compared to 5 years in the M63. This is complicated by the fact that a number of M98s suffer, in our estimation, from premature failures due to a.) a poorly designed rubber boot covering the float switch lever, and b.) poor thermal management that kills capacitors.

In the first cause of early sump pump failure, the boot splits, compromising the integrity of the pump. Water gets in, destroys the electronics, and it’s game over. If that doesn’t get your pump, the thermal management issue can; if the capacitor overheats, it knocks the pump out of commission until it’s fixed. The replacement capacitors cost only $40 from Zoeller, but if you have a poorly designed M98, you can only expect 3-8 years of life before failure, depending on whether you have the boot issue or the capacitor issue. If you have a well designed M98, you can expect 8-16 years of life (which is still less than the 10-17 we’d expect from the M63). We don’t like gambling with sump pumps, and we’d recommend going with the M63 as a sure bet over the M98.

Compared to the Wayne CDU1000, the M98 comes up short in motor power (1/2 vs 1 HP), max flow rate (4,320 gph vs 5,400 gph) and warranty coverage (1 year vs 5 years). Because of the batch of M98s with poor thermal management, the 5-9 years of life we’d expect from the CDU1000 inspire more confidence than an uncertain future with the M98. To put it simply, we’d also recommend the CDU1000 over the M98.

Compared to the M267, there’s no practical reason beyond price to choose the M98. The M267 is far faster (7,680 gallons per hour vs 4,320 gallons per hour), it’s constructed far better, it’s capable of handling up to 2 inch solids (the CDU1000 isn’t rated for solid grinding while the other Zoellers are only rated for up to 1/2 inch solids), and you can typically expect between 10 and 20 years of useful life. There aren’t any well documented premature failure points. It’s simply a set-it-and-forget-it sump pump.

Our Short and Long Term Experiences Installing and Using the Zoeller M98 Sump Pump

As is typically the case with Zoeller pumps, installation is straightforward (connect discharge pipe, level pump, clear float switch, install check valve, plug in pump) and noise levels are low (especially with a silent check valve like the Brady check valve). The most significant issue, again, is that of long-term reliability. While there are plenty of M98s we’ve either installed or seen installed for a number of years, there are also a larger percentage of models we’ve seen fail than with any other sump pump we’ve installed. As we’ve noted above, if you have a problem-free M98, our long-term observations suggest you can get 8-16 years of life from it. However, if you’ve got a poorly designed one, you’ll be lucky to fall on the high end of our 3-8 year lifespan estimate.

Troubleshooting and Installation Tips to Get Your Zoeller M98 Working Sooner

Given the potential for catastrophic failures in the M98, it’s crucial to have a backup system accompanying it in your sump pit. You don’t want to risk a flooded basement with the best of pumps, but it’s even more important with a potentially flawed pump. If you’ve got a large budget, there isn’t a better DC backup pump than the Wayne WSM3300. However, on a smaller budget, we’d recommend the Wayne ESP25. In either case, you’ll also want a water alarm (which you’ll install above the backup float switch, with the backup float installed above the M98’s float switch). We like the Basement Watchdog. Remember that a backup sump pump and a water sensor will save you hours of time and potentially thousands of dollars over even one instance of a flooded basement after a heavy rain and power outage.

Zoeller M98 Sump Pump Pros, Cons, and Value Comparison

In conclusion, it’s hard for us to recommend the Zoeller M98 over the Zoeller M267 (the best choice) or the Zoeller M63 (the closest-priced quality equivalent) or the Wayne CDU1000 (another closely-priced equivalent). The M98 simply has too many points of failure compared to the other three pumps, and even though the majority of M98s out there won’t fail prematurely, there are too many that have for our tastes. We’d recommend the M63 if you want the most reliable AC sump pump out there at the $200 mark, the CDU1000 for the fastest AC sump pump at the $200 mark, and the M267 for the fastest and most reliable AC sump pump under $400. We’d only recommend the M98 if you either a.) are sure of the design of your particular model or b.) have a backup pump installed and are ready to replace the M98 with one of the above pumps if it fails prematurely.

You can buy the Zoeller M98 here, but we’d suggest you instead buy the Zoeller M267 here on Amazon. You can buy the Zoeller M63 here. You can buy the Wayne CDU1000 here. You can buy the Wayne ESP25 here or buy the Wayne WSM3300 here. You can buy a water alarm here. You can buy a silent check valve here.

If you find our work at PumpThatSump helpful, you can put our relentless reviewing of every pump and fixture on the market to the test by shopping via our links above for whatever you need to make your house a home. Despite being self-employed, we promise not to spend it all on health insurance.


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