If you have an automatic condensate drain installed and there's still water in the air lines, the drain may have failed or clogged. Timer drains can have failed solenoids or wrong timing. Float drains can stick from debris or corrosion. The fix is usually cleaning or replacing the drain mechanism.

What you'll see

Water in the air lines despite having an automatic drain system. The drain may not be opening at all (no discharge visible), or it may be opening but not long enough (insufficient drainage). The tank still accumulates water over time. On timer-based drains, you may notice the solenoid click but no water comes out (clogged). On float drains, the float may be stuck in the closed position.
Before you assume this is the problem

If the automatic drain was never installed and you're relying on manual draining, this isn't the cause -- you just need to drain more often. See: Infrequent Tank Draining.

How to diagnose

  1. Check if the drain is actually discharging

    Watch the drain outlet during operation. Timer drains should open periodically and you should see water (and air) come out. Float drains open when the water level rises enough. If nothing comes out during a full work day of compressor use, the drain isn't working. Check: is it powered? Is the solenoid clicking? Is the float stuck?
    Result: Water discharging periodically = drain working. Nothing coming out = drain failed.

  2. Clean the drain mechanism

    Debris, rust particles, and pipe sealant can clog the drain orifice or jam the float mechanism. Disassemble, clean all parts, and reassemble. Check the solenoid on timer drains -- they can burn out or get stuck from corrosion. Check the float on float drains -- it should move freely.
    Result: Clean, free-moving mechanism after service = should work. Damaged parts = replace.

How to fix it

  1. Clean or replace the drain

    Clean the orifice, float, or solenoid. If parts are damaged, replace the drain unit. For timer drains, verify the timer settings are appropriate for your water volume -- too short an interval and the solenoid wears out, too long and water accumulates. For float drains, make sure the collection bowl is large enough for the water produced between drains.

  2. Add a manual drain as backup

    Even with an automatic drain, have a manual drain valve on the tank as a backup. Check it weekly by cracking it open -- if water comes out, the auto drain isn't keeping up. This gives you early warning of auto drain failures.

Common mistakes

Don't set a timer drain to open every 5 seconds thinking 'more is better.' This wastes compressed air (the drain vents air along with water each time it opens) and wears out the solenoid. Set it based on your actual water production -- once every 15-30 minutes is typical for most shops. Also: don't install the drain at the end of a long horizontal pipe from the tank. Install it at the lowest point of the tank or the first low point in the piping, where water naturally collects.

Parts & tools

Replacement drain valve or solenoid. Cleaning supplies. Thread sealant tape. Timer module if replacing timer drain.

Review safety precautions before starting →

Safety

Bleed pressure before disassembling any drain mechanism. The drain is connected to a pressurized system.