Flo vs. Flume 2: Best Smart Water Leak Detectors


When we think of a smart home, our minds usually turn to automation, gadgets, 4K security cameras, and high-tech toys. This makes sense, because these are the devices that provide fun and enjoyment, and allow us to show off to friends.

But a truly smart home needs to be secure and protected. And the more money we spend on home technology, the more damaging a burst pipe or leaky faucet will be. 

For this reason, we wish to spend some time discussing smart water leak detectors. Here, we compare the Flo by Moen Smart Water Detector with the Flume 2 Smart Home Water Monitor.


If you want to skip the full article, here are the key points. 

Flo by Moen Smart Water Detector (920-004) is a smart water-leak sensor that sounds an alarm (audible and via an app) when it comes in contact with water. It is compatible with another device, the Flo by Moen Smart Water Shutoff, which will turn off the water to your home if a leak is detected. However, without purchasing this additional device (MSRP of $500), the Flo by Moen Smart Water Detector can detect water, but cannot do anything to stop damage other than to alert the homeowner. It is a sensor only. However, it is arguably one of the best smart water sensors on the market.

Flume 2 is a whole-home water sensor that reads your water meter to detect discrepancies in water usage. Like the Flo by Moen, this device will alert you if there is a water leak, but cannot do anything to stop the leak. Unlike the Flo, which is a device that senses water in an individual moisture-prone area, Flume 2 is a sensor for the entire house.

Let’s make things even simpler:

  • If you have a water-prone area of your house where you would like to place a water-detecting sensor, the Flo by Moen Smart Water Detector is a nearly perfect product. Place the sensor under a sink, or near a sump pump, and it will alert you (with an alarm and a smartphone notification) if water is leaking.
  • If you want a whole-home water monitoring system that can alert you to leaks and/or irregular usage patterns, Flume 2 is a good (but not perfect) product.
  • If you need a product that can not only detect leaks, but also respond to the leak by turning off water at the source, Flo by Moen Smart Water Shutoff is the best product available. However, this will require a plumber and professional installation.

Flume 2 Overview

Flume 2 is a whole-home smart water detector. It is installed alongside a water meter, and approximates the home’s water usage. If there is a large irregularity in water usage, Flume notifies you with an alert. So, if a pipe bursts, Flume should be able to tell that your house is using an unusual amount of water, and alert you of a potential problem. However, it cannot isolate the location of the problem. And for small leaks, and leaks not impacting your water main, Flume likely won’t be able to detect the problem. For example, a backed up sump pump or a leaking drain will not be detected by Flume, because neither of these will change your home’s water usage.

Flo by Moen Overview

Flo by Moen Smart Water Detector is a single-location water sensor. So, you need a sensor in every location that you feel is likely to sustain water damage. Unlike the typical water detectors you can find in any hardware store, Flo by Moen integrates with an app and can send notifications to your phone. The product is also more sophisticated than most water sensors, and can detect and alert you when a room experiences a temperature or humidity change. However, because it is a single-location device, it cannot tell you anything about water usage. It can also integrate with the Flo by Moen Smart Water Shutoff, which is plumbed into a house’s main water line and can turn off water to minimize water damage.


Both products are quick and easy to install. 

Flo by Moen just requires you to turn on the device and link it to the app. The device can be mounted or set on any surface, so there is no real “installation” required. The process went smoothly during our testing, and user complaints are very rare for installation. The product is cordless, and has a 4 foot extender probe for hard-to-reach areas. You can also purchase longer extenders, and connect them together for up to 18 feet of coverage. We like the simplicity of the battery-powered device, but the CR123A (3V) battery is somewhat unusual, and inconvenient because not everybody stocks them in their home.

Flume 2 Smart Home Water Monitor is also simple to install, but the nature of the product makes it more challenging than the Flo by Moen. Flume doesn’t require plumbing or wiring, but does need to be attached to your house’s water meter. The app is easy to set up and use, and we had no issues. However, Flume is not compatible with every water meter. The company claims the product is compatible with 95% of water meters, but setup can be made challenging (or impossible) by the design and location of your water meter. Flume 2 is also cordless, and is powered by AA batteries.

Smart Home Integration 

Flo by Moen is not compatible with Alexa, HomeKit, or Google Assistant. It uses a proprietary app. If you use this product in combination with the Smart Water Shutoff, then the system will be compatible with smart home voice assistants.

Flume 2 has its own app, but also integrates with Alexa. There is no integration with HomeKit, Google Assistant, or IFTTT, however.

One additional note: both of these devices use 2.4 gHz WiFi.

Functionality & Shutoff Capabilities

Moen makes things very confusing here by having multiple products that use the “Flo by Moen” name. So we will reiterate: the Flo by Moen Smart Water Sensor does not have a water shutoff. It is just a sensor that detects water. If you purchase a separate (MSRP of $500) product called the Flo by Moen Smart Water Shutoff, then both products will pair and be able to shut off your water in the event of a leak.

Flume 2 also lacks an auto-shutoff. Unlike Flo by Moen, there is no compatible product that will pair with the Flume to provide water shutoff capabilities. Because Flume 2 is a whole-home usage monitor, it is theoretically able to detect a leak anywhere on your property (for example, a leak in an irrigation system).

In testing the product, we agree with the user complaints that the sensitivity is too low to detect threats. For example, a slow leak won’t trigger the alarm system. And even a major event like a burst pipe might appear to the system as normal water usage that occurs when the shower is running. So, in this example, you probably won’t be alerted until 20+ minutes of water damage has occurred. This isn’t a flaw in the Flume, necessarily, just a limitation of the in-line monitoring design.

Because the product lacks sensitivity, we feel that the Flume 2 works better for monitoring water usage than as an actual leak detector. It is great for detecting major concerns, such as a busted irrigation system that could cost hundreds of dollars on your water bill without you knowing anything has gone wrong. And it is also great for monitoring your water usage habits, and using it as a tool to reduce water use. Because it can detect significant leaks, some homeowners insurance companies will offer a discounted rate if you have a Flume installed. And because it can help you reduce your water waste, some utility companies will offer a discount on purchasing the Flume 2.

Connection Reliability

Flo by Moen tests well for connection strength and reliability. We had no issues with the connection. There are very few user complaints for connection problems, and almost every tech reviewer has been impressed with the device in this regard.

Flume 2 measures the magnetic field emitted from your water meter, and then transmits this information to a bridge and then to your WiFi. The company claims this is accurate to within 1% of the actual readings on your water monitor. Connecting to a water meter introduces another variable, and a potential failure point for the design. 

In our testing, we didn’t have issues with noticeably inaccurate information. But user complaints of inaccuracy are fairly common. It seems that this is a problem with some water meters but not others. There are also users that say they needed to recalibrate the device frequently, sometimes as often as weekly. In the off chance that you do have issues with the Flume 2, you can rest assured that the company has excellent customer service. Responses are prompt and helpful, and the support staff are very willing to help customers with installation and troubleshooting questions.

Alert System

Flo by Moen has both an audible (beep) alert and notifications via an app. Other tech reviewers have pointed out that the alarm is quieter than it should be, especially considering that it will be placed in distant locations like crawlspaces and under sinks. Because it is a smart device, and the app works well, we can excuse flaws with the audible alarm.

By adding the (expensive) Flo by Moen Smart Water Shutoff, the device gets much smarter, including the alert system. This product features a $5/month subscription service, Flo Protect, which adds sophistication to the product.

Flume 2 displays “real-time” reports and info on water usage via the app. We put “real time” in quotes because there is actually a lag before the reports are available. Along with these reports, you receive app alerts in the event of irregularities.

Final Thoughts

Flo by Moen Smart Water Detector is an affordable way to monitor parts of your home that are at high risk of water damage. With a $500 add-on (Flo by Moen Smart Water Shutoff) and a $5/month subscription, the product will detect leaks and shut off water to your house. If you want a setup that can protect your house while you are on the beach with your phone turned off, you need both the Smart Water Detector and Smart Water Shutoff.

Flume 2 is a WiFi smart water gauge that will alert you to potential leaks or burst pipes. It isn’t perfect, but it is worth every penny if it averts a disaster. Additionally, it can help you monitor excess water usage, like a hose or sink that was accidentally left running.

Neither product is perfect, and neither one is guaranteed to keep your home safe from water damage. But for the price, both are worthwhile investments.