Saniflo Won't Stop Running? Here's How to Fix It (Step-by-Step)

Why Your Saniflo Won't Stop Running

If your Saniflo macerating toilet keeps running and won't shut off, you're experiencing the single most common problem with macerating toilets. The good news? In most cases, this is caused by one of two inexpensive parts that many homeowners can replace themselves.

After 25 years of repairing Saniflo units across Canada, we've narrowed down the "won't stop running" symptom to three main causes — listed here from most to least common.

The 3 Most Common Causes

1. Failed Microswitch (Most Common — ~60% of Cases)

The microswitch is a small electrical component inside your Saniflo unit that detects when the water level rises and tells the motor to activate. Over time, limescale buildup, waste contamination (from a damaged membrane), or simple wear causes the microswitch to stick in the "on" position.

Symptoms:

• Pump runs continuously, even when the toilet hasn't been flushed
• Pump cycles on and off randomly every few minutes
• You hear the motor running when no one has used the bathroom

The Fix: Replace the microswitch — a part that costs approximately $45 CAD and takes about 30 minutes to install.

2. Damaged Rubber Membrane (~30% of Cases)

The rubber membrane (also called a diaphragm or pressure switch membrane) is a thin rubber disc that sits between the wastewater and the microswitch. When this membrane cracks, tears, or becomes stiff from age, waste water leaks through and activates the microswitch constantly.

Symptoms:

• Intermittent start/stop cycling
• Pump runs constantly
• You may notice moisture or water near the microswitch area when you open the unit

The Fix: Replace the membrane (approximately $47-$54 CAD). We strongly recommend replacing both the membrane AND microswitch at the same time — if the membrane failed, the microswitch has likely been contaminated by waste water.

3. Stuck Float or Debris (~10% of Cases)

Some Saniflo models use a float mechanism in addition to (or instead of) the microswitch. Debris, limescale, or a foreign object can prevent the float from returning to its resting position.

Symptoms:

• Problem started suddenly after a particular flush
• You can sometimes "fix" it temporarily by jiggling the unit

The Fix: Open the unit, remove any debris, and clean the float mechanism. If the float itself is damaged, it will need replacement.

Diagnostic Flowchart: Which Part Do I Need?

Follow this simple decision tree:

1. Unplug the Saniflo unit from power. Does the noise stop? If yes, the problem is electrical (microswitch/membrane). If the noise continues, you may have a water supply issue — check that your toilet fill valve isn't running.

1. Open the unit and inspect the membrane. Is it cracked, stiff, discoloured, or does it have waste on the microswitch side? If yes → Replace the membrane AND microswitch.

1. Membrane looks fine? Check for debris around the float or activation mechanism. Clean thoroughly. If the problem persists → Replace the microswitch.

1. New microswitch doesn't fix it? The motor may be drawing too much current due to a failing capacitor or motor seal issue. This typically requires professional service.

Important: Know Your Saniflo Generation

Before ordering parts, you must identify which generation of Saniflo unit you have. The Saniplus alone has had 4 generations (1st Gen, 2nd Gen, 3rd Gen, and the current Saniplus), and the parts are not interchangeable between generations.

Not sure which model you have? Read our guide: Which Saniflo Model Do I Have?

Can I Fix This Myself?

Yes — the microswitch and membrane replacement is the most common DIY repair for Saniflo units. You'll need:

• A Phillips screwdriver
• The correct replacement microswitch for your model/generation
• The correct replacement membrane for your model/generation
• A horseshoe clip (we recommend replacing this every time — they're only about $22 and become brittle with age)
• About 30-45 minutes

Safety first: Always unplug the unit from power before opening it. Wear rubber gloves as the interior will contain wastewater residue.

When to Call a Professional

Call a qualified technician if:

• The motor hums but doesn't spin (likely a capacitor issue)
• You see water leaking from the base of the unit (motor seal failure)
• The unit is tripping your electrical breaker (potential motor or wiring fault)
• You're not comfortable working with electrical components

Get the Right Parts

At UpFlushers, we carry microswitch and membrane kits for every Saniflo generation. Our parts breakdowns show you exactly which parts fit your specific unit — no guessing required.

Shop Saniflo Microswitches → | Shop Saniflo Membranes → | Browse All Saniflo Parts →