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You cannot monitor a rainwater tank with a phone app alone. The app needs a compatible tank-level sensor that measures the water and sends the reading to your phone.
For most homeowners, the simplest choice is the app made for the sensor you install. Some systems show an actual percentage or volume. Others only warn you when the water reaches a high or low point.
As of August 2026, examples include Mopeka Tank Check or Co-Pilot, the YoLink app, Proteus Sensor Cloud, and Home Assistant. The right choice depends more on the sensor, tank, and type of monitoring you need than on the app itself.
What Does a Water Tank Monitoring App Actually Do?
A tank-monitoring app displays information received from a physical sensor.
Depending on the system, the app may show:
- Water level in inches, centimeters, or feet
- Tank percentage, such as 62% full
- Estimated gallons or liters remaining
- High-water or low-water alerts
- Water-level history
- Sensor battery condition
- Connection status
- Several tanks on one dashboard
Some systems can also trigger other equipment. For example, a smart-home system could send an alert when a cistern reaches 20% or shut off an irrigation schedule when stored water becomes too low.
The important point is that the sensor determines what the app can tell you. A simple float switch cannot suddenly provide an exact tank percentage just because it connects to a smartphone.
Apps You Can Use for a Water Tank
Mopeka Tank Check or Mopeka Co-Pilot
Mopeka makes sensors that work with its Tank Check and Co-Pilot apps. Some of its current sensors are designed for non-pressurized liquid tanks and can be configured for water. Compatible sensors can provide actual level measurements instead of only a full-or-empty warning.
Some Mopeka sensors communicate directly with a nearby phone through Bluetooth. A compatible Wi-Fi bridge or other gateway can provide remote access when you are away from the tank.
This type of setup makes sense when you want to check something like:
- A rainwater cistern
- A cabin water tank
- An IBC tote
- A non-pressurized storage tank
Check the exact sensor's supported tank depth, mounting method, tank material, and intended liquid before choosing one. For example, some top-mounted sensors require an opening in the tank rather than simply attaching to the outside.
YoLink App
The YoLink app works with compatible YoLink water-level devices.
One available water-level monitor uses a float switch. It can tell whether water is above or below the switch position and send alerts through the app. A YoLink hub is required for remote app access with this sensor.
That distinction matters.
A float switch placed near the bottom of a rainwater tank can tell you:
Water has dropped below the low-level point.
It does not continuously tell you that the tank is 63% full.
This type of monitoring can still be very useful if your main goal is protecting a pump from running when the tank gets too low or knowing when you need to conserve stored water.
Proteus Sensor Cloud
Proteus Sensor Cloud works with compatible Proteus monitoring hardware. The company's L5 system can use several types of level sensors.
Its float-switch version provides a level alarm at a chosen point. Its laser sensor can measure changing liquid levels continuously and can calculate volume when the tank dimensions are known.
The system connects through Wi-Fi and can provide remote monitoring and alerts.
A top-mounted distance sensor can be useful for a cistern because the sensing element does not have to remain submerged. However, objects inside the tank can interfere with the measurement. Pipes, braces, screens, floats, and uneven surfaces may need to be considered when choosing the sensor position.
Home Assistant
Home Assistant is different from a normal tank manufacturer's app.
It is a smart-home platform that can collect readings from compatible devices and display them on your own dashboard. It is useful when you want your rainwater system connected with other equipment around the property.
For example, Home Assistant currently has integrations for compatible Mopeka devices and Aqvify water-level sensors.
You could use the tank reading to create automations such as:
- Send an alert when the cistern reaches 20%
- Warn when a tank is nearly full
- Display several tanks on one screen
- Record water-level changes over time
- Combine tank level with irrigation controls
Home Assistant offers much more flexibility, but it normally takes more setup than installing a sensor manufacturer's app.
Which Type of App Is Best?
Start by deciding what you actually need to know.
| Your goal | Useful monitoring system |
|---|---|
| Know when water gets too low | Float-switch sensor with alerts |
| Know when the tank is nearly full | High-level float or point sensor |
| See approximately how full the tank is | Continuous level sensor |
| See gallons or liters remaining | Continuous sensor plus correct tank dimensions |
| Check the tank while away from home | Wi-Fi, internet gateway, or cellular-connected system |
| Monitor several smart-home devices together | Home Assistant or similar platform |
| Check the tank only while standing nearby | Bluetooth may be enough |
For a typical rainwater cistern, continuous percentage monitoring is usually more useful than a single high-or-low warning if you are trying to plan irrigation or household non-potable water use.
For a simple rain barrel, however, electronic monitoring may be unnecessary. A sight tube or mechanical gauge may be easier to maintain.
Choose the Sensor Before You Choose the App
The app is only one small part of the system.
Before installing anything, check how the sensor measures the water.
Top-down distance sensors
Ultrasonic or optical distance sensors are installed near the top of the tank. They measure the empty air space between the sensor and the water.
The system converts that distance into water depth.
They can work well because the sensor does not have to sit underwater. However, they need a clear path to the water surface. Internal tank braces, pipes, screens, heavy condensation, or unsuitable mounting positions can cause problems.
Submersible pressure sensors
A pressure sensor can be lowered toward the bottom of a tank. Water pressure above the sensor is used to estimate depth.
These can be useful for deep cisterns, but the sensor and cable remain in contact with the stored water.
If the tank supplies drinking water, do not assume that any electronic sensor, cable, seal, or fitting is suitable for potable use. Potable means water intended for drinking. Verify materials and system requirements before placing equipment in that water.
Float switches
A float rises or falls with the water and changes an electrical switch at one position.
Float switches are simple and useful for alarms, pump protection, and overflow warnings. But one float normally provides only one level point.
Several floats can provide several points, but they still do not give the same continuous reading as a distance or pressure sensor.
External sensors
Review recommended float switches for water tanks and pump-control signals to understand the system’s suction conditions and dry-run protection.
Some sensors can detect liquid through the wall of certain non-metallic tanks.
This may avoid drilling or putting equipment into the water. Compatibility depends heavily on the tank material and wall thickness, so do not assume an external sensor will work through every poly tank or IBC tote.
Bluetooth, Wi-Fi, Hub, or Cellular?
Connection type determines where you can see the reading.
Bluetooth
Bluetooth is useful when your phone will normally be near the tank.
It does not automatically mean you can check your cistern while you are away from home. Some systems add a bridge or gateway to send Bluetooth sensor readings to the internet.
Wi-Fi
Wi-Fi monitoring can provide remote access through the internet without requiring your phone to be near the tank.
Make sure the tank actually has reliable Wi-Fi coverage. A cistern behind a building, inside a metal enclosure, underground, or far from the house may have poor signal.
Hub-based systems
Some sensors communicate with a separate hub using a low-power radio system. The hub then connects to the internet.
This arrangement can provide better coverage than expecting a small battery sensor to connect directly to your home's Wi-Fi.
Cellular
Cellular monitoring can be useful for remote properties without normal internet service.
It adds another connection system to maintain, so it is usually more than a backyard rain barrel needs.
Measure Your Tank Before Buying a Monitor
You need more than the tank's advertised capacity.
Check:
- Total tank depth
- Distance from the sensor to the full-water level
- Shape of the tank
- Tank material
- Available top openings
- Internal braces or obstructions
- Distance to Wi-Fi or the monitoring hub
- Available electrical power
- Whether the sensor will be outdoors
- Whether the tank can freeze
Also check whether the sensor's measurement range covers your tank.
A sensor designed for a shallow container may not work properly on a deep underground cistern.
Getting Gallons or Liters From a Level Reading
Water depth and water volume are not always the same thing.
For a straight-sided rectangular tank, volume changes fairly evenly as the level rises.
A vertical cylindrical tank also has a predictable relationship between height and volume.
Odd-shaped tanks are more complicated. A horizontal cylindrical tank, for example, does not contain 50% of its volume simply because every change in measured height represents the same number of gallons.
If you want the app to display gallons or liters accurately, make sure it supports your tank's shape or allows suitable calibration.
The manufacturer's stated tank capacity can also differ from the usable volume between your overflow and outlet.
A Good Setup for a Rainwater Cistern
For many homeowners who want actual water-level information, a practical setup looks like this:
Tank → compatible continuous level sensor → wireless connection → phone app
Choose a sensor designed for the tank's depth and material. Mount it where it has a reliable reading and where routine inspection is possible.
Then set useful alerts rather than checking the app constantly. For example, a low-level warning can give you time to reduce irrigation use before the tank reaches the pump intake.
If a pump depends on the tank, use proper pump controls and dry-run protection rather than relying only on a smartphone notification. An app alert can be missed, delayed, or lost if the sensor, internet connection, or phone is unavailable.
Do Not Enter a Tank to Install a Sensor
Most tank-level sensors can be installed or serviced from outside the tank.
Do not climb into an IBC tote, cistern, or other enclosed water-storage tank to position a sensor. Tanks can present confined-space and access hazards.
For an underground cistern or a system requiring electrical work, structural modifications, difficult roof access, or entry into a confined space, use a qualified installer.
Frequently Asked Questions
Can my phone measure my water tank level without a sensor?
No. A phone needs information from a separate tank-level sensor or monitoring device. The app displays and records the measurement but does not measure the tank by itself.
What is the easiest app for monitoring a rainwater tank?
The easiest option is usually the native app supplied for a compatible tank-level sensor. This avoids having to build your own smart-home integration. The sensor must still match your tank depth, material, mounting arrangement, and connection needs.
Can an app tell me how many gallons are left in my tank?
Yes, some continuous level-monitoring systems can estimate gallons or liters. The system needs an accurate level reading plus information about the tank's dimensions or shape. Irregular tanks may require special calibration.
Can I monitor an IBC tote from my phone?
Yes. Several sensor types can potentially monitor an IBC tote, including compatible top-mounted, external, or pressure-based sensors. Check the sensor's measurement range, mounting requirements, tank-wall compatibility, and wireless signal before installation.
Can I monitor my tank when I am away from home?
Yes, if the monitoring system connects the sensor to the internet through Wi-Fi, a hub or gateway, or cellular service. A Bluetooth-only connection normally requires your phone to be close to the sensor unless a compatible internet bridge is added.
Is a float switch enough for tank monitoring?
It is enough if you only need a warning at one level, such as "tank low" or "tank nearly full." A single float switch does not normally provide continuous depth, percentage, or remaining volume.
Can a tank-level app control my water pump?
Some smart systems can interact with pumps or controllers, but a phone app should not be the only protection against an empty tank. Use suitable pump controls, including dry-run protection where needed, and make sure the electrical equipment is appropriate for the installation.
Does installing a tank sensor make rainwater safe to drink?
No. A level sensor only measures how much water is in the tank. It does not determine whether the water is safe to drink. Drinking-water use requires suitable collection, treatment, maintenance, current water-quality testing, and compliance with applicable local requirements.
