An overflowing tank wastes water and electricity. A pump left running after the sump is empty runs dry, and a motor that runs dry burns. A starter with a water level controller fixes both: it starts the pump when the tank is low, stops it when the tank is full, and stops it the moment the sump is empty, before the motor burns. Here is how it works, and which BTCO starter does it.
What is a water level controller starter?
A water level controller (WLC) starter runs your pump by the water level, not by someone switching it on and off. Sensors in the tank and in the sump tell the starter how much water there is, and the starter starts or stops the pump by itself. In a BTCO starter, the water level controller works together with the motor protections, so the pump runs only when it should and the motor stays safe.
How it works
| Water level | What the BTCO starter does |
|---|---|
| Tank is low | Starts the pump by itself |
| Tank is full | Stops the pump, so the tank doesn’t overflow (Overflow Trip on the Single Phase Domestic) |
| Sump or source is empty | Stops the pump, so it doesn’t run dry (Sump Empty on the Single Phase Domestic) |
No more climbing to the roof to check the tank, no more water running down the walls, and no more motor running with an empty sump while you sleep.
For homes: the Single Phase Domestic starter
The BTCO FASP-01 Single Phase Domestic starter has the water level controller built in. It is made for homes where a submersible pump fills an overhead tank from a borewell or sump, for 2 HP and 3 HP single phase motors. Along with the water level controller it has normal, cyclic and RTC timers, dry run and overload protection, and low and high voltage protection.
For farms: 3 phase starters with BTCO magnetic sensors
Filling a storage tank or a sump for drip irrigation on the farm? The DOL-03 and FASD-03 star delta starters come in a timer + WLC variant that works with BTCO magnetic water level sensors. It does the same job: start the pump when the tank is low, stop it when the tank is full, and stop it when the sump is empty.
Fitting the sensors
- The sensors are placed in the tank and in the sump, and connected to the starter with a wire.
- There is no distance limit, so the tank can be far from the starter.
- Your local electrician can fit them and run the wire. Setting up the sensors is the customer’s responsibility; our video above shows how the controller works.
Water level control and motor protection work together
A separate water level controller box only switches the pump on and off. A BTCO starter does that and protects the motor while it runs. If the borewell itself runs dry, dry run protection stops the motor even when the tank is still low. If a phase goes missing or the voltage swings, the starter stops the motor and tells you why. See every protection in our submersible motor protection guide.
Which BTCO starters have a water level controller
| Your motor | BTCO starter | Water level controller |
|---|---|---|
| Single phase, 2–3 HP, for homes | FASP-01 Single Phase Domestic | Built in |
| Single phase, 2–5 HP, for farm borewells | FASP-01 Single Phase Agro | No |
| 3 phase, single cable, 3–10 HP | DOL-03 fully automatic DOL starter | Timer + WLC variant, with BTCO magnetic sensors |
| 3 phase, double cable, 7.5–30 HP | FASD-03 fully automatic star delta starter | Timer + WLC variant, with BTCO magnetic sensors |
| 3 phase on juice line, 2 phase or 3 phase | Combined DOL and Combined star delta | No |
Ask for the timer + WLC variant and the magnetic sensors when you order a DOL-03 or FASD-03. If you already have a BTCO starter with WLC, you can add the sensors to it. Also useful: what a fully automatic starter does, what the display tells you and why submersible motors keep burning.
Frequently asked questions
What is a water level controller starter?
It is a starter that controls the pump by the water level. It starts the pump when the tank is low, stops it when the tank is full, and stops it when the sump or source is empty, so the tank never overflows and the pump never runs dry.
Does the starter start the pump by itself when the tank level is low?
Yes. When the water in the tank drops to the low level, the starter starts the pump on its own, and switches it off again when the tank is full.
What happens when the sump is empty?
The starter stops the pump so it doesn’t run dry. On the BTCO Single Phase Domestic starter the display shows Sump Empty.
Which BTCO starters have a water level controller?
The FASP-01 Single Phase Domestic starter has it built in. The DOL-03 and FASD-03 3 phase starters have it in their timer + WLC variant, which works with BTCO magnetic water level sensors. The Combined starters and the Single Phase Agro model have no water level controller.
Can I add the water level sensors to the starter I already have?
Yes, if your BTCO starter has WLC (the timer + WLC variant of the DOL-03 or FASD-03, or the Single Phase Domestic). Your local electrician can fit the sensors and connect them to the starter.
How far from the starter can the sensors be?
There is no distance limit. The sensors connect to the starter with a wire, so they can be at a tank or sump far from the starter.
Who fits the water level sensors?
Your local electrician can fit the sensors in the tank and sump and run the wire to the starter. Setting it up is the customer’s responsibility; our setup video shows how the controller works.
Does the water level controller replace dry run protection?
No, they work together. The water level controller watches the tank and sump. Dry run protection watches the motor current and stops the motor if the borewell itself runs dry. A BTCO starter has both.
Get a starter with water level controller
Call or WhatsApp us with your motor’s HP, your power supply, and where the tank and sump are, and we’ll suggest the right BTCO starter. Compare every model on our submersible pump starters page, or visit your nearest BTCO Starters dealer. More answers in our motor starter FAQ.
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