Key takeaways
Listen to the pump first. A pump that's silent, one that hums, and one that runs but gives no water each have a different cause.
The checks you can do safely are the plug, the breaker, the water tank, and turning the fan by hand with the pump unplugged.
Parts inside the motor and the wiring are a technician's job.
Table of contents
Listen first: silent, humming or cutting out
Hitachi and Mitsubishi pumps that have power but won't run
Pump runs but no water comes out
What the technician will do
1. Listen first: silent, humming, or cutting out
A water pump not working sounds different depending on what's wrong. Open a tap, stand next to the pump for half a minute, then match what you hear.
What you hear | Likely cause | What you can check | Who fixes it |
|---|---|---|---|
Nothing at all | No power reaching the motor, or a faulty pressure switch (the small box that turns the pump on when you open a tap) | Push the plug in firmly, try another socket, check the breaker | You, if it's the plug or breaker; otherwise a technician |
A hum, but nothing turns | A failed capacitor (the small part on the motor that gives it the kick to start), or the impeller (the spinning wheel inside) jammed with limescale | Unplug it, then try turning the fan at the back of the motor by hand. If it's stiff, something is stuck | A technician |
Runs for a bit, then stops, or a light blinks | The pump's safety cut-out has switched it off because the motor got too hot or the tank ran dry | Check the tank has water and the pump has space around it to cool | You first; a technician if it keeps happening |
Two things to avoid. If the breaker trips again as soon as you reset it, leave it off, because there may be a current leak. And if the pump is humming, unplug it rather than leaving it on.
If your pump won't stop rather than won't start, that's a different problem, covered in why your water pump won't switch off.
2. Hitachi and Mitsubishi pumps that have power but won't run
Hitachi. Hitachi Thailand's water pump manual lists four reasons a Hitachi water pump is not working when the motor won't turn: a loose plug or faulty main switch, a faulty motor coil or pressure switch, an impeller locked by limescale, or a capacitor that has leaked or melted. Only the first is something you can fix yourself. So if your Hitachi water pump has power but won't run and the plug and breaker are fine, call a technician.
Mitsubishi. Mitsubishi's Super Pump troubleshooting page explains that its ½ to 1.5 horsepower pumps have a safety cut-out that switches the motor off when it gets too hot. Models with an electronic control panel, like the UMCH, iMCH and ICM series, also show an error code or a blinking light. If your Mitsubishi water pump has power but won't run and a light is blinking, look the code up in your manual first.
3. Pump runs, but no water comes out
If you can hear the motor running but no water comes out, the problem is on the water side, not the electrics. The Hitachi manual gives three causes:
the tank has run dry, or the pipe the pump draws from is leaking
the one-way valve that stops water draining back down the pipe isn't closing
the pump has lost the water it needs inside it before it can pull water up
Start by checking the storage tank has water. Hitachi recommends running the pump from a storage tank rather than straight off the mains, because mains flow can be uneven. If the tank is full and still nothing comes out, switch the pump off and call a technician.
4. What the technician will do
A technician will check the power reaching the pump, then test the pressure switch, capacitor and motor. If the impeller is jammed, they'll open the cover and clear the limescale. If no water is coming, they'll check the pipe and the one-way valve, then refill the pump so it can draw water again.
To get it sorted, post a water pump repair task on gigit, set a budget or leave it open to offers, and choose from the offers local gigit heroes send. You pay through gigit's Safe Payment System, backed by Kasikorn Bank. A technician will find the fault and get your water running again.