Causes
- The pump loses its prime while the unit sits in storage — The Superior 6000S (model LEH-S601S-WUS) uses a self-priming pump that draws water up from the 6-gallon tank through a feed tube. When the humidifier is drained and stored dry for the off-season, that tube and the pump chamber fill with air. On the first start after storage the pump motor spins (you can hear the whirr), but it can't pull water, so the internal water-level sensor never sees flow and the unit flashes the red water-drop icon and shuts off after a few minutes — even though the tank is full. This is the most commonly reported 6000S failure, and it typically happens after the unit has been inactive for months.
- Debris or mineral scale jamming the pump's internal check valves — The pump has small internal check valves plus a suction filter. Hard-water scale can cement the valves shut, and owners have found that the inlet/suction filter can deteriorate over time and get sucked into the pump, blocking the impeller. The pump then buzzes but moves little or no water, so the unit times out and shows the low-water alert despite a full tank.
- Dirty or misaligned water level sensor giving a false "no water" reading — The unit relies on a water-level sensor to confirm water is flowing; if the sensor is covered in scale or debris, or the water feed tube isn't fully seated after you reassemble the unit, it reports low water even when the tank is full and the pump is fine.
- The top assembly is seated the wrong way — The fan/filter top must be rotated so the arrow on the filter holder points toward the front of the base. If it's seated incorrectly, the pump's water feed doesn't line up with the tank outlet, which triggers the red water-drop warning even with a properly filled tank.
How to Fix
- Run the "reactivate/prime the pump" procedure in the VeSync app — Open the VeSync app, select the humidifier, and look for the pump reactivation or priming option in the device settings. Run it several times — owners report needing up to a dozen attempts before the pump catches. If the app can't connect to the unit, skip to the manual priming steps below.
- Manually prime the pump with a syringe or turkey baster — Turn off and unplug the unit, then lift off the top fan assembly. Using a small syringe, pipette, or thin-tipped baster, inject water into the hole in the filter housing and into the hole on the fan housing that feeds the pump's water tube (the ports on the corners where the top connects to the base). Add roughly 100 mL total, wait about 10 seconds so the water works into the tube, reassemble the unit, and power it on immediately. This is the fix that resolved the issue for the majority of owners who reported it.
- Do a full power reset and listen for the pump to catch — Press and hold the power button on the control panel until the unit fully restarts (not just a short press). On restart you should hear a gurgling sound as the pump finally draws water up. If the unit then runs without showing the red water-drop error, the prime has been restored.
- Verify the top assembly orientation — Lift the top off and reseat it so the arrow on the filter holder points to the front of the base, matching the arrows on the tank and base. A mis-seated top is a common trigger for the false low-water alert, so confirm this before digging into the pump.
- Clean debris and scale out of the pump — If priming fails, unplug the unit, remove the top, and locate the pump at the base of the filter housing. Disassemble the pump head carefully and clear any scale or filter fibers from the internal check valves and impeller, then rinse the parts in clean water. Also inspect the suction filter: if it has deteriorated or started to shed fibers, replace it with a new one so debris can't be pulled into the pump again.
- Lubricate the pump inlet seal if cleaning doesn't hold — Some owners found that after storage the rubber seal at the pump inlet and the plastic barb at the top of the filter holder dry out and no longer seal, which lets the pump lose suction. Apply a thin coating of an O-ring/silicone lubricating compound (such as Syl-Glyde) to both sealing surfaces, reassemble, and retry priming. This fixed the issue permanently for owners where water-only priming was only a temporary fix.
- Update the firmware through the VeSync app — In the app's device settings, check for a firmware update and install it. Several owners reported that a firmware update resolved the false low-water behavior, and Levoit has shipped firmware improvements for the pump/water-detection logic since launch.
- Contact Levoit support if the pump still won't prime — If none of the above works, the pump motor or sensor may be faulty. Contact Levoit support at [email protected] or (888) 726-8520 (Mon–Fri, 9:00 am–5:00 pm PST/PDT) with your order invoice. Levoit's team walks you through the priming steps and will arrange a repair or replacement under the 2-year limited warranty — several owners with the same issue received a replacement unit after support's troubleshooting failed.