To check a water tank or reservoir level from a distance, install a water level sensor at the tank and send the level to your phone. Add a Smart Control Box and the pump starts automatically when the level is low and stops when the tank is full, so it is looked after even when nobody is there.
Farm reservoirs, rooftop water towers at factories and fish farm storage tanks are often some distance from the office or home. Nobody knows the water is nearly gone until the pump runs dry and burns out, or the tank is full but the pump keeps running and water pours out of the overflow. This article covers the common ways to control water level, how a pump can start and stop by water level, and how to estimate the cost.
Water Tank Level Controllers: Float Switch vs Electrode Probe vs Ultrasonic vs Submersible Sensor
Water level control on the market falls into roughly four types. The first two mostly just switch on or off when the water reaches a certain height. The last two give a continuous level reading, which suits remote viewing on a phone:
| Type | How it measures | Shows the water level? | Things to watch | Suitable |
|---|---|---|---|---|
| Float switch | A float rises and falls with the water surface and moves a switch | Only "reached / not reached" | Fails if the float sticks or the cable tangles; cannot show how much water is left | Household tanks, simple top-up |
| Electrode probes (level electrodes) | Several probes at different heights conduct when they touch water | Only which probe height has been reached | Electrodes scale up and rust and need regular cleaning; the water must conduct electricity | High/low level control of building tanks and factory water towers |
| Ultrasonic level sensor | Mounted at the top of the tank, sends sound waves down to measure the distance to the surface | Yes, continuous reading | Does not touch the water, but foam, condensation in the tank or mounting too close to the surface affects readings | Open tanks and reservoirs |
| Submersible (pressure) level sensor | The sensor head sits on the tank bottom and converts water pressure to depth | Yes, continuous reading | The sensor head and cable stay submerged; silt on the bottom needs regular cleaning | Deep tanks, wells and storage tanks |
If you only need "stop when full, top up when low", a float or electrode is enough. To view the level on your phone, keep records and get notified of abnormal levels, choose a level sensor that gives continuous values and connect it to an internet-connected device.
Why Monitor Water Level Remotely? Where It Matters Most
Farm reservoirs
Irrigation reservoirs are often at the edge of a field or on a hillside, and a daily trip to check the level takes time. In the dry season the level drops quickly, and you may only find the reservoir nearly empty when it is time to irrigate, when the pump cannot draw water and the field goes unwatered. Checking the level on your phone tells you when to refill and when to conserve. For automatic watering, see How to Build an Automatic Sprinkler System for Farmland.
Factory water towers and cooling ponds
Factory water towers supply general water other than for process, washing or firefighting, and a shortage is often discovered only after a production line stops. With the level on your phone, managers know the state of the tank even after work or on business trips.
Fish farm storage tanks
Water changes and top-ups both depend on the storage tank, and if the level is too low you cannot change water. Fish farms already look after aerators and water quality, so seeing the water level on the same phone saves a trip. For the problem of aerators and pumps stopping together in a power cut, see How to Choose a Power Outage Alarm.
How to Automate a Water Pump: Starts When Level Is Low, Stops When Full
Automatic switching has three parts: measuring the water level, judging the condition, and switching the pump.
- Measure the level: FarmerPack has a water level module with a range of 10 to 450 cm and accuracy of ±1 cm. Readings are sent to the cloud at regular intervals, so you can see the water level and its trend curve on your phone.
- Set the condition: on your phone, set "start the pump when the level drops below this value" and "stop the pump when the level rises above this value". No programming is needed and it takes effect as soon as you save. The same condition can also send you an SMS or email.
- Switch the pump: the Smart Control Box switches the power on and off, so you do not need to replace your existing pump. The pump's own power is carried by an external circuit, and a qualified electrician wires large or three-phase pumps through an external circuit.
If mains power is available on site, choose the mains-powered control box. For a remote tank where running power is difficult, choose the energy-saving version (solar plus lithium battery), which suits low-power, intermittent devices such as solenoid valves. FarmerPack comes with solar power as standard and can run for 30 days or more without sunlight.
Does it still switch automatically if the internet goes down?
Yes. When the connection is lost, the Smart Control Box keeps running on the last settings downloaded from the cloud. However, to control automatically by the water level measured by FarmerPack while offline, you need the LoRa communication version, so tell us when you order.
How do you stop a pump from running dry during a water outage?
"Cut power automatically when the water supply stops" is a feature many people look for. The approach is to measure the level at the pumping source too (the lower tank, well or reservoir). When the source level is below the set value, the pump will not start even if the tank above is short of water, and you are notified to deal with it. A pump running dry for a long time overheats and is easily damaged, so one extra condition saves a repair.
How Can You Tell Early When a Pump Keeps Running or Runs Dry?
There are three common situations, and you can see all of them in the water level curve on your phone:
- The pump is on but the level does not rise: the pump may not be drawing water (source is empty), the pipe may be leaking, or the check valve may be stuck.
- The level stays high but the pump is still running: the float or the original controller may have failed, and water keeps flowing out of the overflow, wasting electricity and water.
- The level falls faster than usual: there may be a leaking pipe, or someone is using a lot of water.
Abnormal-level notifications can be sent by SMS, email or app push. When the pump trips or the whole area loses power, the tank will not be refilled. For this, add a Power Outage Alert Module, which notifies you when it detects a power cut, a voltage sag or abnormal current.
Manual Checks vs Float Switch vs Remote Level Monitoring: What's the Difference?
| Comparison Item | Manual checks | Float / electrode auto top-up | Remote level monitoring + Smart Control Box |
|---|---|---|---|
| Someone on site? | Every day | Normally not, but you only find out when it breaks | Check on your phone, go only when something is wrong |
| Can you see how much water is left? | Only on site | No | Anytime, with history curve |
| When the controller fails | Found only when someone walks by | Often found only after overflow or dry running | Notified as soon as the level is abnormal |
| Can you set several conditions? | No | Only a high point and a low point | Yes, for example do not start the pump if the source level is too low |
| Replace the existing pump? | No | No | No, just add a control box |
How Much Does It Cost?
The cost of remote level monitoring with automatic switching depends mainly on these items:
- How many tanks to measure: each tank you want to watch (water tower, lower tank, reservoir) needs its own level measurement.
- How many pumps and valves to control: this decides the number of Smart Control Boxes and whether you choose the mains-powered or energy-saving type.
- Communication: 4G, NB-IoT, Wi-Fi or LoRa, chosen by site signal and whether you need automatic control while offline. Versions that use a SIM card have a data fee.
- Cloud platform: an annual fee for the mobile app and platform.
- Installation: you can install it yourself or add on-site installation (currently available in Taiwan only). Have a qualified electrician do the pump wiring.
Taiwan prices are as shown in the online quote tool. Choose the items you need and you will see an estimated cost first: Smart Control Box online quote and FarmerPack (with water level module) online quote.
Frequently Asked Questions
Q1: Can the water level module be installed on my own water tank or reservoir?
Tank material, height and opening position differ from site to site. Before installation, send us photos of the tank, its depth and the planned mounting position. We will confirm how to install it and then give you a quote.
Q2: Do I have to remove my existing pump and float switch?
No. The Smart Control Box is added to the pump's power supply circuit and only switches power on and off. You can keep the existing float switch as a backup. Have a qualified electrician confirm the wiring against the site's power distribution.
Q3: Can I switch the pump on and off from my phone?
Yes. Besides starting and stopping automatically by water level, you can switch the pump manually from your phone and set a run time, after which it stops by itself.
Q4: Is this suitable for a household water tank?
This setup suits places where nobody is on site much and running out of water affects work, such as farm reservoirs, factory water towers and fish farm storage tanks. For a household tank, a float switch is usually enough.
Q5: How will I be notified of an abnormal water level?
You can set notifications by app push, SMS or email when the level is too low or too high, and notify several people at the same time.
Q6: Can it be used where there is no internet?
Yes. Choose the 4G or NB-IoT version, which has a built-in SIM card and needs no on-site network. If you need automatic level-based control while the connection is down, choose the LoRa version. Please check the signal on site with your phone first, and tell us the location if you are unsure so we can check together.
Want to ask first?
Tell us the type of tank (water tower, reservoir, storage tank), roughly how deep it is, the voltage and number of pumps, and whether mains power and internet are available on site, and we will help work out the setup. Feel free to contact us, or go straight to Online Quote, choose your items and submit.
