APEC ROTL-600 and ROTL-600PH have programmed flushing that can run without a drinking-water draw. Their July2025 manual describes short automatic flushes after power returns, pump operation and a day without use. Compare the actual indication and sequence with that model's instructions. Persistent operation, leakage or a protection alarm needs assessment rather than repeated resets.
The named models include automatic flushing
The APEC ROTL-600/ROTL-600PH manual, V1.3 July 2025 describes a programmed flush setting. It lists a 20-second flush after power is restored, after the pump has run for two hours producing water, and after 24 hours without drinking-water use.
Those timings describe these models and this revision. They are not a universal permitted run time for other tankless systems, and they do not replace the separate startup or replacement-filter flushing procedure. Record whether the operation follows one of the listed events and ends as described.
A storage-tank shutoff test answers a different question
The Watts Premier RO-PURE manual describes a conventional tank system with different production and shutoff behavior. Our RO draining-after-a-full-tank guide addresses that arrangement. Do not conclude that a tankless unit's short automatic flush is a failed tank shutoff valve.
Automatic flushing is also an operating feature recognized by EPA's WaterSense RO specification, which accounts for the applicable flushing scheme when testing efficiency. That does not establish that these APEC models carry a WaterSense label or that all drain flow is normal.
Distinguish a flushing indication from protection faults
APEC's manual separately identifies E1 water-leak protection, E2 continuously running pump timeout protection and E3 frequent pump start/stop protection. Its indicator combinations distinguish these conditions from flushing. Match the complete pattern with the actual diagram rather than treating every light or beep as a filter reminder.
A leak is not scheduled flushing. Avoid wet electrical equipment; if isolation cannot be done safely, stay clear and arrange qualified help. The manual warns against plugging or unplugging the adapter with wet hands or wet surroundings and against unauthorized disassembly or modification.
Preserve the evidence instead of resetting repeatedly
Note the model, indication pattern, preceding power interruption or filter replacement, and whether operation is brief, continuous or repeatedly restarting. Ask the manufacturer or technician to assess a protection condition or unexplained operation. Do not bypass the leak detector, disable a protection function or repeatedly power-cycle the equipment to hide the warning.
For noise associated with the receiving drain, air-gap assessment is a separate check. Continue RO maintenance using the actual tankless instructions; a normal automatic flush is not contaminant testing or proof that all filters remain effective.