Build or buy a water tank level monitor?

The parts for a solar ESP32 LoRa tank sensor and a receiver for the house come to about $123 at the sellers' own prices, before shipping, wire and the evenings it takes to make them a monitor. Build one if the building is part of what you want; buy one if what you want is the level of the tank, an alert when it falls, and nothing more to look after.

By Luke Patterson, co-founder of Trivertix. Last checked October 13, 2026.

What the parts cost

This is one way to build it, close to the projects people share: a LoRa board on the tank that reads a waterproof ultrasonic sensor and sends the distance, a second board in the house that receives it, and a panel and a battery. Each price is the one the seller's own page listed for a single part.

Order the boards for the radio band your country uses. Heltec sells this one for 433 MHz, 863 to 870 MHz and 902 to 928 MHz. Trivertix uses LoRa at 915 MHz.

ESP32 LoRa board, on the tank: $17.90
The same board, in the house: $17.90
Waterproof ultrasonic sensor: $15.90
6 V, 2 W solar panel: $20.95
Solar charger for the battery: $14.95
2,500 mAh lithium battery: $14.95
Weatherproof box: $19.95
The parts together: $122.50

Not counted: shipping, antennas if a board comes without one, wire, connectors, cable glands, a mount that holds the sensor square over the water, and a spare of whatever you break first.

Sources, read October 13, 2026: Heltec: WiFi LoRa 32 (V3), DFRobot: A02YYUW Waterproof Ultrasonic Sensor, Adafruit: 6V 2W Solar Panel, Voltaic P126, Adafruit: bq24074 solar charger, Adafruit: Lithium Ion Polymer Battery 3.7v 2500mAh, Adafruit: Large Plastic Project Enclosure, IP66.

What the parts do not include

The shared projects make the radio look like the hard part. It is the easy one: the boards come with LoRa on them, and the examples send a reading on the first night. The work is in everything around it.

The code on the tank: Wake, read the sensor a few times and keep the steady reading, send it, and go back to sleep. The battery lasts as long as the board stays asleep.
Distance to gallons: The sensor gives the distance down to the water. You measure the tank, set the distance at full and at empty, and write the sum that turns the rest into gallons and percent.
The receiver: A board in the house that hears the tank and shows the level somewhere: a small screen, a dashboard, or a home automation server you already run.
Alerts: A message when the level crosses a line, sent by a service you sign up for and keep working.
Weather: A sealed box, a hole for the sensor and the cable, and a panel aimed at the sun. Then the first storm shows where the water gets in.

None of it is beyond someone who has built a project or two. But count the evenings after it is finished as well: when a reading stops coming in, you are the one who finds out why.

The weather a box on a tank lives through

Read the limits on each part before it goes outside, and remember that a sealed box in full sun gets hotter than the air around it.

The sensor: Rated IP67, and to work from 5°F to 140°F
The battery: Charged only from 32°F to 113°F, and never below freezing

The battery is the one to plan for. A summer afternoon on a dark box can pass the top of that range, and a clear winter morning puts sun on the panel while the battery is still below freezing. Choose a charger that reads the battery's temperature and waits, and a battery with a sensor for it to read.

Source, read October 13, 2026: DFRobot: A02YYUW Waterproof Ultrasonic Sensor.

Source, read October 13, 2026: Battery University: BU-410, Charging at High and Low Temperatures.

A build and Trivertix, side by side

Trivertix works the same way: an ultrasonic sensor at the top of the tank, LoRa radio to the house, and a solar panel. What you pay for is the work above, done once and tried in the field. The first pilot units went onto stock tanks in Karnes County, Texas, and the link held at three-quarters of a mile through hills and mesquite on our pilot ranch.

An ESP32 LoRa build and Trivertix
	An ESP32 LoRa build	Trivertix
The sensor	Waterproof ultrasonic, 3 to 450 cm	Ultrasonic, mounted at the top of the tank and reading down to the water. It reads tanks up to 16 feet deep.
The radio	LoRa, on the band you order	LoRa at 915 MHz from transmitter to receiver. No SIM card, and no cellular or satellite modem.
Power on the tank	Panel, charger and battery you pick and wire	Solar panel and rechargeable batteries
In the house	A second board, and whatever display you give it	A display for the tank level and four status lights. It plugs into the wall and joins your home Wi-Fi.
Readings	As often as your code wakes	About every 15 minutes
Phone and alerts	What you set up and keep running	On iPhone, Android and web, with one high and one low alert line. None to read your level on the receiver. A monthly plan adds the app.
Price	About $123 in parts, and your time	Announced at launch

Source, read October 13, 2026: DFRobot: A02YYUW Waterproof Ultrasonic Sensor.

When each is the better tool

Build one when

You like the building, and the monitor is the excuse.
You want the data in a system of your own, in your own format.
You have one tank near the house and a spare weekend.
A reading that stops for a week while you fix it would do no harm.

Buy one when

Livestock or a household depend on the tank.
The tank is out of sight of the house, and the drive to it is the thing you want to stop making.
You want an alert you never have to think about.
Someone else in the family has to be able to read it.

Buying need not mean Trivertix. Satellite, cellular and radio monitors are compared here, with what each connection costs over five years.

Questions about building a tank sensor

How much do the parts for an ESP32 LoRa tank sensor cost?

About $123 for one tank, at the prices the sellers listed on October 13, 2026: two LoRa boards, one for the tank and one for the house, a waterproof ultrasonic sensor, a small solar panel, a charger, a battery and a weatherproof box. Shipping, wire, cable glands, a mount for the lid and anything you break along the way come on top.

Which ultrasonic sensor works in a water tank?

A sealed one with its transducer in a waterproof head, not the open twin-eyed kind sold for robots. The one in our parts list, DFRobot's A02YYUW, is rated IP67, reads from 3 to 450 cm and gives its accuracy as ±1 cm. Its maker rates it to work from 5°F to 140°F, so check that range against the inside of a box in the sun.

Can a homemade tank sensor run on solar power?

Yes, with a panel, a charger made for one, and a battery, and with code that puts the board to sleep between readings. Mind the battery's limits: Battery University gives 32°F to 113°F as the range a lithium-ion battery may be charged in, and no charge at all below freezing, which plates metal lithium inside the cell. On a frozen morning in the sun, the charger has to know to wait.

Be first in line.

The waitlist hears the price and the launch date before anyone else.

Join the waitlist