Why is there water on the floor of my walk-in cooler?

Water on a walk-in floor is never just a mop job. It's a slip hazard in a room where staff carry heavy loads, a health-inspection finding, and — left standing — a floor-panel killer, because water that migrates into panel seams destroys insulation and rots floors from inside. The good news: floor water comes from a short list of sources, and where the water shows up tells you which one you have.

Source one: the condensate drain — the usual suspect

Every defrost cycle melts frost off the evaporator coil, and that water is supposed to leave through the drain pan and drain line. When it doesn't, it ends up on your floor:

• A clogged drain line — slime, debris, or ice blocks the line and the pan overflows, dripping under the evaporator. Puddles directly below the coil unit point here.
• A frozen drain line (freezers) — freezer drain lines need heat tape and proper pitch; when the drain heater fails, meltwater refreezes in the line, then the next defrost overflows the pan. The signature: ice stalactites under the coil and sheet ice on the floor beneath it.
• Bad pitch or a trap problem — a line that sags holds water and eventually blocks. This is an installation flaw that presents as a recurring "clog."

Note that some controllers can relay a pan overflow float switch as an external alarm — KE2's EXT ALARM and Dixell's EA are commonly wired to exactly that.

Source two: the door — condensation and ice melt

Humid outside air sneaking past a bad gasket condenses and freezes around the door area; every warm spell or defrost melts some of it onto the threshold. Water or ice concentrated at the door end of the box is an air-leak finding, not a drain finding — and the fix (gaskets, sweeps, closer adjustment, door discipline) is cheap and also cuts your energy bill and your coil-icing problem at the same time.

Source three: sweating — the box working against humidity

In a humid kitchen, exterior panel surfaces and exposed cold lines can sweat, and floors just inside frequently-opened doors collect condensation from the air exchange. Persistent general dampness (rather than localized puddles) in summer points here. Ventilation around the box and door discipline are the levers; a box that sweats heavily year-round may have a panel losing its insulation value — worth a professional look.

Source four: an actual water leak

Walk-ins near dish pits, ice machines, or plumbing walls sometimes collect someone else's water. If the puddle doesn't map to the evaporator, the door, or humidity patterns — or it's there even in dry winter weeks — look uphill: what's on the other side of that wall or above the ceiling panels? Trace before assuming the cooler is the culprit.

The 10-minute trace

1. Map the puddle. Under the evaporator = drain. At the door = infiltration. General dampness = humidity. Unrelated corner = external leak.
2. Look up. Drips from the coil unit or pan confirm drain problems; ice on the ceiling near the door confirms infiltration.
3. Check the drain outlet outside the box — a healthy drain visibly discharges after defrost.
4. Fix the cheap causes now (clear the drain outlet, fix gaskets, mop and dry the seams), and get a tech for frozen drain lines, failed drain heaters, and pan repairs — those involve heaters and disassembly. The verified lists for Nashville and Birmingham cover contractors who handle exactly this.

And whatever the source: dry the floor completely and keep it dry. Standing water in a walk-in is the one problem on this site that injures people directly — everything else just costs money.