What Is a Float Switch in a Septic System?
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Quick answer
A float switch is a sealed, buoyant sensor that hangs in a septic pump tank and tilts as the water level changes. It tells the control panel when to start a pump, when to stop it and when to sound the alarm. A tangled or failed float is one of the most common causes of septic alarm calls.
A float switch looks like a small plastic bob on a cord, and it is easy to underestimate. Inside a pump tank, though, it is the part that tells the pumps what to do and tells you when something is off.
What does a float switch do?
As water rises in the tank, the float rises with it and tilts. Tilting closes or opens an electrical contact inside the float, and that signal travels up the cord to the control panel. When the water drops, the float tips back and the signal changes again. In this way the water level itself controls the equipment.
How many floats does a system use, and what are they for?
Most pump tanks have more than one float, each hung at a different height and given a different job. The arrangement varies by system, but a typical setup includes these roles:
- Pump off. Keeps the pump from running dry once the tank has emptied to a safe level.
- Pump on. Starts the pump when the tank fills to its working level.
- High-water alarm. Trips the buzzer and light when the level climbs above the normal range.
- Override or backup. Some systems include an extra float for added protection.
The alarm float is the one behind most high-water alarms. Another float handles the pump cycle. Labels inside the control panel or on the cords can help a technician tell them apart.
What goes wrong with float switches?
- Tangled cords. Floats can wrap around each other or around a pipe and stop moving freely.
- Grease and debris. Buildup can weigh a float down or hold it in one position.
- Worn-out switches. The contact inside can fail after years of use.
- Cracked housings. Water gets in and the float stops working or floats incorrectly.
- Wrong position. A float that has slipped from its set height changes how the whole tank behaves.
Symptoms include a pump that never starts, a pump that will not stop, an alarm with no clear reason, or no alarm when the tank is full. Any of these deserves a call to a technician.
How do you take care of float switches?
Floats live inside a tank that contains wastewater and gases, so they are never a do-it-yourself job. A scheduled visit under your maintenance contract lets a technician look at them, clean them and test the alarm. Careful use of the system also helps: keeping grease and wipes out of the drains means fewer deposits on the floats.
If you suspect a float problem, see our aerobic septic alarm repair page or our guide to the control panel, float switch and alarm. Call 832-789-5357. Se habla español.
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Quick questions and answers
- Can a float switch cause a false alarm?
Yes. A float that is stuck, tangled or failing can trip the alarm even when the water level is normal. A technician needs to check the float and the level before you assume the system is fine.
- How long does a float switch last?
It depends on the product, the conditions in the tank and how well the system is maintained. Floats wear out with use, so they are checked at every service visit rather than replaced on a fixed timetable.
- Can I pull a float out of the tank to check it?
No. The tank holds wastewater and gases that can be dangerous, and floats are wired to power. Leave inspection and replacement to a trained technician.
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