Best Sump Pump Alarm (2026): Liberty, Level Sense, YoLink

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Quick answer from a licensed plumber: A sump alarm should keep working when the pump and the power fail, so pick one with its own battery, set its float above the pump’s on level, and put it on a different circuit than the pump. Add phone alerts if nobody is home.

Our take: a pump maker’s alarm with a full manual? The Liberty ALM-2: Check the Liberty ALM-2 on Amazon. No 9V battery to replace? The Level Sense Sump Pump Failure Alarm: Check the Level Sense alarm on Amazon. Phone alerts? The Level Sense Pro: Check the Level Sense Pro on Amazon. A hub-based sensor? The YoLink YS7904F: Check the YoLink sensor on Amazon.

A sump alarm is a second float and a horn. It does not move water. It tells you the pit is filling faster than the pump empties it. Wayne’s manual says “an independent high water alarm or back up pump should be used,” and Little Giant says a back-up system “and/or an alarm should be installed.” This guide compares alarms from the makers’ documents. For the pump, see our best sump pump guide and sump pump brands guide. If yours is failing now, read sump pump not working.

Sump Pump Alarms Compared

Alarm	Reaches you by	Its own backup power	Sound, per maker	Warranty term
Liberty ALM-2	Horn and beacon	9V battery	86 dB at 10 ft	3 years
Level Sense standalone	Horn on site	Built-in rechargeable	120 dB	2 years
Level Sense Pro	Wi-Fi: email, push; text on a plan	Internal rechargeable	100 dB	2 years
YoLink YS7904F	App through a hub	2 AAA in the sensor	105 dB (listing)	2 years
Zoeller APak 10-4011	Horn and lights	2 AA, not included	80 dB at 10 ft	3 years
SJE Xpert Alert WiFi	Wi-Fi or Ethernet: text, email	Rechargeable lithium	80 dB at 10 ft	5 years from shipment

Read from maker documents on September 29, 2026. Sound figures are on different bases, so compare within a basis. We did not link the Zoeller or SJE alarms: we found only third-party Amazon listings for them, or none, and preferred Amazon- or maker-sold links.

Three Kinds of Sump Alarm

Standalone plug-in alarm. A float in the pit wired to a horn on the wall: Liberty ALM-2, Zoeller APak, SJE Tank Alert AB, Level Sense standalone. It helps only if someone is home to hear it.
Wi-Fi or app alarm. Level Sense Pro, SJE Xpert Alert WiFi, and YoLink through its hub. These need internet, and the router needs power to reach you.
Alarm built into a pump or backup system. Backup controllers sound alarms for their own pump, power and battery. Basement Watchdog’s CITS-50 manual lists pump, power, battery and fuse alarms, and its WiFi module adds email, text and push alerts. Wayne’s HALO50, a primary sump pump, uses Wi-Fi and Bluetooth with an app, and its manual says to use an independent alarm or backup pump as well. See battery vs water-powered backups.

Basement Watchdog also sells 110 dB water alarms (BW-WA360 and BWD-HWA) that sound at about 1/32 in. of water on the floor. They are floor alarms (the BW-WA360 runs on a 9V battery), not pit alarms, but they suit the spot beside a pit. Little Giant’s 303HWXT (115 V, float included, 85 dB at 10 ft per the listing) is sold by Amazon.com, but we found no manual for it, so we say nothing about its warranty or circuit rules. For other leaks, see where to put water leak sensors.

Sensor, Battery and Testing: What the Manuals Say

Sensor. Liberty lists a tethered float for sewage pumps and a snap-on sensor for sump pipes. Zoeller recommends its 10-4012 mechanical float for sewage, and says to inspect and clean a 10-4011 reed float used in sewage after any high water incident.
Battery. Liberty: replace the 9V when the indicator lights or yearly. Zoeller’s chart gives 1 to 2 years of battery life with normal use on AC plus batteries, and about 1 year on batteries alone.
Testing. Liberty says test every 6 months. Zoeller says test once a week. Basement Watchdog says test its water alarm every 6 months.

Top Pick: Best-Documented Plug-In Alarm

Liberty Pumps ALM-2 High Water Float Alarm

115 V plug-in · 4 ft power cord · 9V battery backup with low-battery indicator · 86 dB siren at 10 ft per the manual (the product page also says 88 dB) · 360-degree red beacon · tethered float with 20 ft cord · auxiliary dry contacts · NEMA 1, indoor only · 3-year limited warranty

Liberty publishes a full manual for the ALM series. It says the 9V battery must be in the unit at all times and should be replaced when the yellow indicator lights or every 12 months, and that the alarm should be tested every 6 months. Silence quiets the horn for 6 hours. The ALM-2 has no app; the Wi-Fi versions carry “-EYE” in the model name, and their Amazon listings showed either no offer or two or fewer units when we looked.

Liberty’s warranty covers three years from the date of purchase, proved by a dated sales receipt. Batteries are excluded, and the warranty does not apply if the electrical cord is cut, damaged or spliced. The text we read does not mention authorized sellers. The listing is sold by Amazon.com.

Manual states battery, test and mounting height (48 to 66 in.)
9V backup with a low-battery alert, per the manual
Auxiliary contacts can feed a home monitoring system
3-year warranty on a dated receipt

Manual lists the tethered float for sewage pumps; the product page says sump, effluent or sewage
Battery is yours to replace, at least yearly per Liberty
Liberty’s page lists both 86 dB and 88 dB
No phone alerts on the ALM-2

Verdict: The pick if you want an alarm from a pump maker with a readable manual, bought from Amazon itself.

Check the Liberty ALM-2 on Amazon

No 9V to Replace: Rechargeable Standalone Alarm

Level Sense Sump Pump Failure Alarm

Plug-in horn with a 15 ft float switch · 120 dB siren (maker, no test distance given) · built-in rechargeable lithium polymer battery, up to 1 week without AC power per the maker · built-in test and silence · indoor and clear-water use only · no Wi-Fi · 2-year limited warranty (Level Sense warranty page)

This is the plainest kind of sump alarm: a float in the pit and a loud horn on the wall. Level Sense (Sump Alarm, Inc., St. Louis) says the alarm mounts on the discharge pipe and its battery recharges itself, so there is no 9V to replace. The maker’s page says the siren sounds for several days; the Amazon listing says the battery powers the siren for 40 hours. They do not match, so plan on the smaller number.

Level Sense’s warranty page lists two years, and the coverage ends if the product is damaged by external causes “such as fire, water, lightning,” improperly installed, modified, “sold by original purchaser,” or repaired by anyone the maker has not authorized. A claim means shipping the unit freight prepaid with evidence of purchase. The same page has the buyer release the maker from claims if the system fails to report an event. We could not open the model manual, so we cannot quote its outlet rules. The listing is sold by Sump Alarm, Inc., the company behind Level Sense.

120 dB is the loudest figure any maker gives here, though no distance is stated
Rechargeable battery built in, per the maker; no 9V to swap
Float switch and mounting hardware included

No phone alerts, so it only helps if someone is home to hear it
Indoor, clear-water use only, per the maker
Warranty ends if water or fire damages it, or the original buyer sells it
We found no model manual to read

Verdict: The pick if someone is usually home, you want a very loud horn, and you would rather not replace a 9V battery.

Check the Level Sense Sump Pump Failure Alarm on Amazon

Wi-Fi Alerts, Free Email and Push (Per Maker)

Level Sense Pro Wi-Fi Sump Pump Alarm

Wi-Fi alarm with float switch · also watches for power loss, leaks, temperature and humidity · internal auto-recharging backup battery · 100 dB horn, IP20 housing (maker) · free email and push alerts, text and voice on an optional yearly plan (maker) · Android and iOS apps · 2-year warranty, standard on all Level Sense alarms (maker)

Level Sense lists text, email, push and audible alerts for the Pro. Its product page says “Unlimited text and phone calls are available with a low cost yearly subscription,” and its SMS and voice plan page says email and push alerts “remain unlimited and free” and that the plan covers the Pro. An older Pro page still says “No subscription required,” so count on free email and push, and on the yearly plan if you want texts or calls. The same company’s 90 dB Sump Alarm Wi-Fi model also keeps text and voice on a paid plan.

The unit keeps watching on its internal battery when power fails, per the maker. Getting the alert to your phone still takes your router and modem. Level Sense lists “cloud check-in monitoring,” but what we read does not say what it sends when the unit goes offline. The listing is sold by Sump Alarm, Inc., the maker. The two-year warranty page above is the only Level Sense terms sheet we found; the maker says the SMS and voice plan extends the warranty while it stays active.

Email and push alerts are free, per the maker
Power-outage alarm and cloud check-in monitoring, per the maker
Reaches you by email or push while you are away

Unlimited texts and calls need a yearly plan, per the maker
Needs home Wi-Fi and an account
100 dB is lower than the standalone Level Sense
Depends on your router having power to reach you
Wi-Fi band not stated in what we read

Verdict: The pick if nobody is home all day and free email and push alerts are enough, with texts and calls as a paid option.

Check the Level Sense Pro on Amazon

App Alerts Through a Hub

YoLink Water Level Sensor With Float Switch (YS7904F)

Battery-powered sensor with a pendant float · connects to a YoLink hub, sold separately · 2 AAA batteries pre-installed · built-in sounder, 105 dB per the Amazon listing · app push, email and SMS alerts per the listing · indoor use only · 2-year warranty on battery-powered products (YoLink policy)

YoLink’s quick start guide says the sensor “does not connect directly to your WiFi or local network” and needs a YoLink hub (the SpeakerHub or the original hub) for remote access. The guide is silent on how alerts reach you in an outage. The listing names SMS among the alert types and gives a small monthly allowance, so read its terms before relying on texts.

The guide says the sensor is for indoor use and its body “should not be installed where it may get wet,” so the float goes in the pit and the sensor stays on the wall. The sounder is optional and using it shortens battery life. YoLink’s warranty runs to “the original user,” and it excludes products “subjected to acts of God (such as floods, lightning strike or electrical surge, or earthquakes, etc.).” The listing is sold by Yosmart, the maker.

Runs on two AAA batteries, so it needs no outlet near the pit
Push, email and SMS alerts through the app, per the listing
Can trigger other YoLink devices such as a siren, per the listing

Hub required and not included
Warranty is for the original user and excludes floods and surges
The 105 dB figure comes from the listing, not the guide
SMS allowance is limited, per the listing

Verdict: The pick if you already run YoLink devices, or want a battery-powered sensor with app alerts and can add a hub.

Check the YoLink YS7904F on Amazon

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Before You Buy

Decide who hears it. A horn helps only if someone is home. If not, choose Wi-Fi or a hub and confirm any fee on the exact model.
Check its power. Wi-Fi alerts still need the router.
Read the warranty below, and keep the receipt and serial number.

Outlet, Circuit and Wiring Notes

Separate circuit. Liberty’s pump manual says an alarm “must be connected to a separate electrical circuit.” Zoeller’s APak sheet says it “should be connected to a circuit separate from the pump circuit” and shows “DO NOT” plug the alarm into the pump’s circuit.
GFCI. We found no GFCI wording in the Liberty, Zoeller APak or SJE alarm documents we read. For the pump, Wayne says the receptacle “must be protected” by a GFCI “for added safety,” and Zoeller says it “may be protected.” Plumber’s note, not from a maker: if the alarm plugs into the same GFCI outlet as the pump, or an outlet that GFCI protects, one trip cuts power to both, and the alarm is left on its battery, if it has one. Have a licensed electrician set up the outlets.
Codes and standing water. Liberty says qualified personnel must install and service its alarm to applicable electrical and plumbing codes. It warns that submerged electrical connections can energize floor water, and says not to enter water above the protective equipment’s rating. Do not wade into a flooded basement to service an alarm.
Low-voltage float. Zoeller says its control switch operates on low voltage to reduce shock hazards and suggests a licensed electrician or service person. SJE says its float terminals are for the float only: do not apply power.
Indoor only. Liberty says its ALM devices are not for outdoors, “not even when placed in a secondary enclosure.” Do not cut or splice the float or power cord: Liberty says to replace the unit if the sensor or power cable is damaged or severed, and its warranty excludes a cut, damaged or spliced electrical cord.

Warranty Fine Print

Level Sense: two years; ends if damaged by fire, water or lightning, improperly installed, sold by the original purchaser or serviced by an unauthorized party; ship freight prepaid with evidence of purchase; you release the maker from claims if the system fails to report an event.
Liberty ALM series: three years from purchase on a dated receipt; batteries excluded; void for a cut, damaged or spliced electrical cord.
YoLink: two years for battery-powered products, original user, no floods or surges.
Zoeller APak: three years from purchase by the end user, covering the purchaser and subsequent owner; no shipping or labor allowance.
SJE Rhombus: five years on most catalog products, counted from the date of shipment.
Basement Watchdog 360 water alarm: five years from purchase for the end purchaser; it must reach the factory within 30 days of the failure with the bill of sale, and no one else may inspect it.

FAQ

Do I need a sump pump alarm if I have a battery backup?

Makers say to consider one. Wayne’s manual says an “independent high water alarm or back up pump should be used” where high water could damage property. Little Giant says a back-up system “and/or an alarm should be installed.” Liberty says to consider a back-up pump “as well as an alarm.” A backup controller alarms for its own pump, power and battery; see our battery backup guide.

Where does the alarm float go?

Above the level where the pump turns on, and clear of the pump’s own float. For its snap-on sump sensor, Liberty says the activation point should be “slightly higher than the pump activation point.” Its manual says to route the sensor cable so it does not interfere with the primary pump’s float. Zoeller says to suspend its control switch above the pump turn-on level and not to install its sensor “in direct line of incoming liquid.” See vertical vs tethered floats.

Do Wi-Fi sump alarms need a subscription?

It depends on the maker and the model. Level Sense says email and push alerts on its Pro are free, and sells an optional yearly plan for unlimited text and voice alerts; its 90 dB Sump Alarm Wi-Fi model also keeps text and voice on a paid plan. SJE says its Xpert Alert WiFi has “No monthly fees or contracts.” Basement Watchdog says the same for its module. YoLink’s listing gives a small monthly SMS allowance. Each needs home internet and a powered router.

How loud is a sump pump alarm?

From 80 dB to 120 dB on maker figures, and the numbers are not on one basis. SJE gives 87 dB for its Tank Alert AB and 80 dB for its Xpert Alert WiFi, Zoeller 80 dB for its APak, and Liberty 86 dB, all at 10 ft. Level Sense gives 120 dB (standalone) and 100 dB (Pro) with no distance. Compare within a basis.

Will the alarm work in a power outage?

Only the battery-backed ones. Liberty and SJE’s Tank Alert AB use a 9V battery, Zoeller’s APak two AA batteries you buy, and Level Sense a built-in rechargeable one. Zoeller says with AC only its low-battery alarm is disabled. Basement Watchdog’s manual says notification in an outage needs a router or modem with built-in battery backup, or a UPS.

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, the Liberty ALM-2 listing was sold by Amazon.com, and the Level Sense and YoLink listings were sold by the makers’ own companies (Sump Alarm, Inc. and Yosmart); all were in stock. 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

Bottom Line

Pick the alarm for how you will hear it: a loud horn if someone is home, Wi-Fi or a hub if not. Give it its own battery and its own circuit, set the float above the pump, test it on the maker’s schedule, and have an electrician set up the outlets.