Without question, water is the world's most precious natural resource. Indeed, 71% of the planet is covered by water, and up to 60% of the human body itself is made up of water. In many parts of the world, getting clean water is difficult, and even in developed countries, our use of water is tapping the limits of ground wells and aquifers.

If you want to understand how much water your household appliances use and help prevent waste from leaks, you might be interested in the Phyn Plus, a device you install in-line with the water main of your home. This device can not only tell you how much water each toilet flush uses, but can also shut down the water in your house if it detects a catastrophic leak that could result in a flood in your house.


I'm not a scientist, so won't pretend to fully understand how the Phyn Plus works. According to their marketing literature, the device uses an ultrasonic flow sensor that measures pressure waves 240 times a second. It is also the only connected water monitor that works this way: Other similar products use turbine flow sensors that are apparently less precise and more prone to breaking since the turbine is a moving part. This sensor allows the device to measure with high precision exactly how much water is being used at any point in time. There are also temperature and pressure sensors to measure those values within your home.

Full view of the Phyn Plus water sensor

The device itself is rather large, at 8.5" (215mm) long, 5.6" (142mm) wide, and 1.5" (38mm) deep. Since the Phyn Plus is installed in-line with your incoming water pipes, you have to make sure there's enough space to do the installation. In addition, you'll need a power source nearby. In my installation, I was able to run the power to an outlet in the ceiling that the hot water heater was also using.

Phyn is backed by Belkin International and Uponor, so has a solid foundation, reducing the risk of the company disappearing, leaving the consumer with a worthless in-line device.


Dimensions 2.97" (7.54cm) L x 8.43" (24.41cm) H x 5.6" (14.22cm) D
Weight 5.5 lbs / 2.5 kg
Network 2.4GHz 801.11b/g/n
Power 110/220V 19W power supply
Certifications IP55 certified, NSF certified for potable water
Price $699 (no monthly charges)


If you're handy with plumbing, you can probably install the Phyn Plus yourself, but make sure you know your limitations. Hiring a plumber to do the installation will run roughly $200, depending on where you live.

View of a water meter in a house before installing the Phyn Plus

To use the Phyn Plus, your incoming water pipe has to be smaller than 1.25" in diameter. Apparently that should accommodate the vast majority of households in the United States. The device can be installed inside or outside, but should be placed right after the water meter. Since I live in Minnesota, and it's common for the temperature to get to -20F/-29C in winter, the water comes into the basement from under the cement slab to prevent the water from freezing.

View of the Phyn Plus installed after the main water meter

The plumber who did my installation had never used a Phyn Plus before, but had installed a couple competing products. The process was very straight forward - shut off the water, cut the pipe, insert the Phyn Plus, and turn everything back on. The whole process took roughly 45 minutes, and the only complaint he had was that while the device has a blue dot showing which direction is up, he felt it should've had an arrow showing the flow direction like other devices do. Other than that, he said installation was really easy and straight forward.

The device itself, while just a big black box, does have a blue LED strip on the side that lights up when you first turn it on. While it'd be cool if it simulated water flowing through the pipes, the fact that most of these will be installed in places that nobody will actually see makes that frivolous except for the initial installation.

Initial Setup

After the Phyn Plus is installed, you have to complete the configuration of the device. That consists of downloading the Phyn Plus app from your app store of choice and following the guide to connect the device to your WiFi network. After that, it runs a test to make sure it can start and stop the flow of water, and that's it. The whole process took about 20 minutes, most of which was simply waiting for the testing to complete.

One of the steps that seems fairly important during the setup is to select how many water fixtures you have in your house. This was something I had never really thought about before. While it's easy to count the number of toilets you have, I hadn't really thought about things like the ice maker and water dispenser that's built into the refrigerator, or the two water spigots on the outside of the house. Altogether, there are 24 devices in the house that consume water, a number that was far higher than I would've initially guessed.

Learning Phase

Even after the Phyn Plus is installed, it won't shut your water off if it detects what it thinks might be a leak. Instead, it enters into a learning mode where it watches your water usage and tries to categorize it all based on what it sees. The app indicates that this takes around 1,000 water events, where an event is any starting and stopping cycle of water. In my house, this whole process took a little over a month to complete.

The device is really accurate right out of the box, but you can assist by either confirming what Phyn Plus detected was correct, or by changing the guess to what the actual device was. The day it was installed, I went around to each toilet in the house and used both flush settings on each, then looked at the app to confirm the water usage. I had never thought about the amount of water the toilets used, but was able to identify that a basic flush uses 0.9 gallons (3.4 liters), while a larger flush uses 1.6 gallons (6 liters). After each flush, I pressed the water drop next to the device to confirm the usage. I did the same for all of the sinks in the house, as well as the showers, just to give the Phyn Plus a baseline (and because it was cool watching the water use statistics in real time!).

Three screenshots showing water usage for a specific day via Phyn Plus app

During the first week, I noticed that when I washed my hands immediately after flushing the toilet, Phyn Plus lumped both events into the toilet category, so instead of the toilet using 0.9 gallons, it used slightly more, like 0.95 gallons. I was concerned that Phyn wouldn't be able to separate the water usage, but after a few more days, it started to label the sink usage separately from the toilet usage, which I was pretty impressed with. If you want to be Big Brother, it's also a great way to confirm that your children are washing their hands after using the bathroom.

Although the Phyn Plus won't automatically shut your water off during the learning phase, it will still alert you if it detects an unusual flow. For example, a week after the installation, I took a long shower in the morning to help wake me up. When I got out of the shower, the app warned me about the flow because it went on for so long. I was able to tell the app that this was simply a shower and after a couple of instances of this, Phyn Plus has learned I sometimes take long showers and hasn't complained about it since.

Three screenshots pasted together showing the Phyn Plus alert notifications and acknowledgement

After roughly 1,000 events, the app alerts you that it's able to go into automatic shutdown mode if you choose to enable that functionality, but it never actually stops learning. I hadn't used my irrigation system before the Phyn Plus' learning phase was over, so the first two times it turned on, the app alerted me of a very high water flow and asked if it should turn off the water. After that, it hasn't asked about the irrigation system, even when I've run it manually at different hours.


While Phyn does offer a dashboard for businesses that want to monitor multiple properties, there is no such web presence for individual homeowners, making the app a requirement.

When you first bring up the application, you're presented with stats on your system, including water temperature, pressure, and current flow. It's interesting to see the water temperature coming into the house. In Minnesota, after a long winter, the water coming into the house was 58F/14.4C, and since the Phyn Plus can sense not only the temperature, but also can detect ice crystals in the pipes, it can warn you if you need to warm it up. The main page also tells you how much water you've used in the month compared to other Phyn Plus users of the same household size, when the last plumbing check was performed, and whether there are any current alerts to respond to. You're also presented with three buttons: Run a Plumbing Check, See Water Use, and See Water Events.

Three screenshots showing the water pressure check in the Phyn Plus app

Since your water pipes are closed system, the Phyn Plus can check the plumbing by turning off the incoming water and monitoring the system for any unusual changes in pressure. It does this on a nightly basis, but you can run the test at any time, and I'm happy to report that it works extremely well. I left a bathroom sink faucet on so that it dripped once every five seconds, and the Phyn Plus successfully detected the leak. Unfortunately, it can't tell you where the leak is so if you can't find it yourself, you might have to engage a plumber, but it's better to find the leak when it's small, especially if it's a pipe in your walls.

Clicking on the See Water Use button brings up a calendar where you can see the overall amount of water used, the number of water events, and the amount of water your house has used compared to other Phyn Plus customers with the same number of family members. On the calendar, the darker the color blue, the more water that was used on that day. You can click on any of the days to get roll-up data about that day, or can scroll up to see previous months.

Three screenshots showing the calendar view daily view and water used by washing machine in Phyn Plu

Clicking See Water Events brings up all of the events from the current day, with the most recent event at the top of the screen. From here, you can filter based on specific fixtures, or change the sorting based on amount of water used.

Under settings is where you configure how many fixtures you have in the house, how many people live there, and, most importantly, is where you configure the automatic shutoff. When turned on, Phyn Plus will automatically turn the water off when it detects an unusual flow that you don't respond to within a certain amount of time. Normally this is good, but I don't recommend turning it on right away, even when it's done with its learning cycle, as I did receive a couple of alerts while taking a long shower. After a couple of months, I have stopped receiving any false alarms though, and feel it's safe to turn the feature on, even when home.

Related to the automatic turnoff is an "away mode." With this mode activated, the Phyn Plus forgoes waiting for the user to acknowledge any alerts. If it detects any water flow for 60 seconds, it will send an alert and automatically shut the water off in the house. This can mean the difference between a few hundred gallons of water flooding your house or thousands of gallons destroying your house.

Overall, the app gets the job done, but it seems to be lacking some polish. Every time I open the app, it has to go through a loading screen that takes five seconds to finish, even if I try to pin the app in memory on my phone. None of my other home automation tools have this issue.

The app also isn't always intuitive. For example, in the calendar view, there's no indication on how to see previous months, and instead of swiping from left to right like most other calendar apps, you have to swipe from bottom to top. It's not a showstopper, but isn't a good user interface.

Another idiosyncrasy is that clicking See Water Use takes you to the calendar, and if you click back from there, you're taken to home page again, but if you click See Water Events instead, and then click back, instead of being taken back to the main menu, you're taken to the calendar for some reason. It works, and you get used to it, but it's a little strange at first.

Finally, the app seems to have a bug that, when you change what an event was classified as, will occasionally take you back to the main menu. There's no indication the change was successful without going back into the menu, and since this doesn't happen all the time, feels like an issue that needs to be addressed.

Aside from these minor quibbles, the app doesn't get in the way of using the device and getting proper insights, it could just use some extra work from the development team.

Water Insights

So did I learn anything interesting from the Phyn Plus during the review or is its only use preventing major flooding in your home? I'm happy to say I learned quite a bit.

The first interesting piece of information, aside from the difference in water usage between a regular and large toilet flush, was that the seal on one of my toilets was not good. While it would usually be ok, there were times when it would drain 0.4 gallons (1.5 liters) from the tank into the bowl every couple of hours. Since this was a slow leak, it would only manifest if the water level in the tank went below a certain amount that caused it to refill. We never heard it, and only noticed it by seeing toilet use on the app. While this didn't really save money, and arguably cost more to fix than the water I was using, it helps use less which is good for the environment.

Another interesting piece of information is that, while I knew lawn irrigation used a lot of water, I had no idea exactly how much it used. Now, from using the Phyn Plus, I can see that it's not uncommon to use over 1,500 gallons (5678 liters) of water just to keep the grass green. Everyone I asked vastly underestimated the amount of water an irrigation system uses, so while it's not driving any specific changes in my life, it's something I keep in mind in the back of my head and I understand why my city partners with Rachio to install smart irrigation systems in everyone's home.


The Phyn Plus is able to integrate with Alexa and Google Home if you want to utilize voice control to find out how much water you've used or to turn your water on and off. Personally, I don't find this feature very useful and it's potentially harmful since someone could turn your water off via voice from outside your home.

Three screenshots showing configuration pages for Phyn Plus integrations with Alexa Google and IFTTT

The device also integrates with IFTTT, which again has limited usefulness in my eyes. The example that's given by the company is that you could turn up your thermostat if the Phyn Plus detects a freeze warning in the pipes, but I'm not sure how helpful this would be compared to simply getting an alert from your home automation system about a low temperature in the home.

One feature that would be useful, but that I wasn't able to get working with IFTTT, is forcing Phyn Plus to go into away mode if everyone's cell phone in the house leaves a geofenced location. However even that has a potential negative as it means you could never run the washing machine or dishwasher, or have the irrigation system run when you left the house, so use caution.


Upon first glance, the Phyn Plus, at $699 without installation, appears to be a very expensive gadget. The truth is that, while it is very expensive, it can potentially save you thousands of dollars if it can prevent a catastrophic leak, such as a hose that disconnects from your washing machine. That said, it's an insurance policy that you may never actually use.

Speaking of insurance, take note that some companies will offer up a discount on your insurance if you install one of these. Unfortunately, the list of partners is currently very low. A recent study by LexisNexis indicated that having an automatic water shutoff device could save both customers and insurance companies a lot of money, so it's unfortunate that so few insurance companies offer discounts for having a device like the Phyn Plus. According to the research, "in-line water shutoff systems correlate with a decrease in water claims events by 96%" and that "those without water shutoff systems reported a 10% increase in water claims events over the same time period."

What happens if you lose power when the device is checking the water pressure or after you turn the water off? The Phyn Plus has a manual control that allows you to open/close the valve with a screwdriver that's attached to the device. That said, depending on where your device is installed, it may be difficult to access.

Finally, when installing any Internet of Things (IoT) device, it's important to put it on a separate network. If the company or device becomes compromised, you don't want it to be able to access anything else on your home network.


Overall, if the price of the Phyn Plus doesn't scare you away, I can highly recommend installing the device in your house. The insights into your home's water utilization are interesting, it can help you reduce your overall water usage by identifying leaks in your toilet or pipes, and can prevent a catastrophic nightmare if a pipe were to burst in your house. That said, it's only this theoretical catastrophic event that will cause you to save money with the Phyn Plus; the other use cases will only help you preserve Earth's most precious resource, which for many, is enough of a reason to install the device.

View of the Phyn Plus lit up blue

There are competitors that I haven't looked at, such as the Flo by Moen, but while the devices are cheaper up front, their advanced features cost extra every month. Even excluding the fact that the ultrasonic flow sensor is superior to a turbine, for someone who wants to avoid a recurring charge, the Phyn Plus is the obvious winner.

Ultimately, the device does exactly what it sets out to do, and while the mobile app could use a little polish, the device is very accurate and does a great job figuring out where the water is being used in the house. If you're considering an automatic water shutoff device, I would not hesitate to purchase the Phyn Plus.

Phyn Plus
Water usage monitoring Leak detection Automatic shutoff No monthly fee
Very expensive Large device App needs a little polish Might not be DIY install


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