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Commercial Commercial Dishwasher: Leaking — Causes & Fixes

Compiled by Resultex Media Group · Editorially reviewed · Last verified August 2026

Quick answer: Water on the floor or out the door is usually an owner-level cause: an overflowing/clogged scrap accumulator or drain, a missing or loose end plug/wash-arm cap, too much detergent (foam-over), or the machine not sitting level. Check the scrap accumulator and drain first, look for a missing wash-arm end plug in the scrap tray, cut back detergent if it's foaming, and confirm the machine is level with a slight tilt to the rear. Water leaking from the fill solenoid, drain seal, or internal plumbing while the machine is off is a technician repair.
Food safety: Standing water on the floor is a slip hazard (OSHA) and, near clean-side storage, a contamination and pest risk. Keep water off the floor and store sanitized ware elevated and protected from splash, per the Food Code. Note: returning food to 41°F does not by itself make it safe. If the time/temperature history is unknown, segregate the product and follow your food-safety plan; the FDA Food Code’s time-as-a-public-health-control provisions require specific written procedures, and local health-department requirements may differ. When safety cannot be verified, discard it.

Check in this order (5-minute diagnostic)

Work top to bottom — the quickest, most-likely checks are first.

  1. Overflowing / clogged scrap accumulator or drain. If water runs onto the floor, the scrap accumulator or scrap drawer may be full/clogged, or the building drain may be backed up.
  2. Missing or loose end plug / wash-arm cap. Water coming out of the door area can be a missing or loose end plug on the wash arm; a dislodged plug often ends up in the scrap trap tray.
  3. Detergent foaming / overfill. Excess detergent or too high a water level causes foam that overflows the door.
  4. Machine not level. A machine that isn't level (or tilts forward) leaks from the door and washes unevenly.
  5. Leaking fill/water solenoid, drain seal, or internal plumbing. Water leaks even with the machine off, or from behind/under the cabinet — points to the fill solenoid, drain ball/seal, vacuum breaker, or internal plumbing.

Likely causes, checks & fixes

Likely causeHow to checkWhat to doWho
Overflowing / clogged scrap accumulator or drainIf water runs onto the floor, the scrap accumulator or scrap drawer may be full/clogged, or the building drain may be backed up.Clean the scrap accumulator and scrap drawer. If it still overflows, the drain is likely clogged — call a plumber. · see: won't fillDIY-safe
Missing or loose end plug / wash-arm capWater coming out of the door area can be a missing or loose end plug on the wash arm; a dislodged plug often ends up in the scrap trap tray.Find the plug (check the scrap accumulator drawer) and reinstall it hand-tight. If it's lost, order the replacement part.DIY-safe
Detergent foaming / overfillExcess detergent or too high a water level causes foam that overflows the door.Reduce the detergent quantity (have your chemical supplier set the dose) and confirm the fill level is correct.DIY-safe
Machine not levelA machine that isn't level (or tilts forward) leaks from the door and washes unevenly.Level the machine with a slight tilt to the rear per the manual; on hard-plumbed units have a technician set it.Basic
Leaking fill/water solenoid, drain seal, or internal plumbingWater leaks even with the machine off, or from behind/under the cabinet — points to the fill solenoid, drain ball/seal, vacuum breaker, or internal plumbing.Call a qualified technician (or plumber for the supply/drain hard-connection). Do not disassemble the solenoid or plumbing yourself. · see: won't fillTechnician

Who can do it: DIY-safe owner-doable · Basic simple part swap · Technician refrigerant/gas/electrical — call a licensed pro.

How to do the safe fixes

Owner-doable procedures only. Anything on the "Technician" list above needs a licensed pro.

Clean the drain/scrap screen and scrap tray DIY-safe
  1. Turn the machine off and, if it holds water, drain it (lift the drain ball/actuator until the water is out).
  2. Lift out the drain/scrap screen and remove any foreign object (a stuck knife, fork, or spoon) from the drain area.
  3. Rinse all food debris off the screen at the sink or with the pre-rinse hose - do not bang it on the table to knock food loose.
  4. Remove and rinse the scrap tray/accumulator drawer; clean it after each meal, or hourly when very busy.
  5. Reinstall the screen in its proper position in the sump housing before refilling.

· Tools: Sink or pre-rinse hose, Disposable gloves · Source: CMA EAH/EC Owner's Manual (Cleaning the drain screen; Machine Will Not Hold Water; Empty the Scrap Tray)

Clean the wash and rinse arms and unclog spray jets DIY-safe
  1. Turn the machine off and remove the upper and lower wash/rinse arms per your manual.
  2. Hold each arm and check that water would blow from every jet; use a toothpick to open any clogged jet - do not enlarge or gouge the openings.
  3. If an arm is still restricted, unscrew the stainless end plug and flush the inside of the arm tube at the sink to clear scraps.
  4. Rinse the arms clean, reinstall the end plug hand-tight, and reseat the arms fully so they spin freely and spray reaches all ware.
  5. Run a test cycle and confirm even spray from both arms.

· Tools: Toothpick or soft pick, Sink for flushing, Disposable gloves · Source: CMA EAH/EC Owner's Manual (Cleaning the washer arms); Champion UH130 (clean spray arms)

Prime the chemical lines (detergent, rinse aid, sanitizer) DIY-safe
  1. Confirm each color-coded pick-up line is in the correct container (on CMA: red = detergent, blue = rinse aid, clear/white = sanitizer) with tube stiffeners in place so the tube can't curl and suck air.
  2. With the master switch ON, hold each prime switch until product runs through the line and discharges into the sump/injection point (no air bubbles).
  3. Run one full cycle and watch each injection tube to confirm detergent, rinse aid, and sanitizer are all feeding.
  4. On low-temp machines, test the final rinse at the surface of the ware with chlorine strips - it should read at least 50 ppm (target 50-100 ppm).
  5. If concentration is off, adjust the pump feed (CMA uses adjustable cams) or call your chemical supplier; never exceed a 6% sodium hypochlorite solution.

· Tools: Fresh chemical containers, Chlorine test strips (low-temp machines), Disposable gloves · Source: CMA EAH/EC Owner's Manual (Chemical Feeder; Activating Machine; Check Operations; 50-100 ppm)

Verify the machine is actually sanitizing DIY-safe
  1. Identify your machine type from the data plate: high-temperature (hot-water sanitizing) or low-temperature (chemical sanitizing).
  2. High-temp: run a rack and check the final rinse reaches at least 180°F at the manifold (165°F for a stationary-rack single-temperature machine); confirm the utensil surface reaches 160°F using a maximum-registering thermometer or heat-sensitive label placed on a plate through the cycle.
  3. Low-temp: run a cycle and test the final rinse at the ware surface with chlorine strips; it must read at least 50 ppm (target 50-100 ppm).
  4. Record the reading per your health department's practice.
  5. If the machine can't reach sanitizing temperature or concentration, stop using it to sanitize, manually wash-rinse-sanitize ware in a three-compartment sink, and call for service.

· Tools: Chlorine test strips (low-temp), Maximum-registering thermometer or heat-sensitive temperature label (high-temp) · Source: FDA Food Code 4-501.112 (hot water), 4-501.114 (chemical), 4-703.11 (utensil surface 160°F); CMA (50-100 ppm)

Descale / deliming - what is safe DIY vs. call a specialist Basic
  1. Confirm scale is the problem: white chalky film on tank walls, arms, jets, or booster, usually with hard water.
  2. For light routine scale, follow the deliming instructions in your machine's own manual exactly, using only the manufacturer-approved delimer, with gloves and eye protection, and rinse thoroughly.
  3. Do not mix delimer (acid) with detergent or sanitizer (chlorine) - mixing acid and bleach releases toxic gas.
  4. Heavy scale, or deliming the booster heater and internal plumbing, uses highly caustic agents - have a qualified chemical specialist do it.
  5. Prevent recurrence with water treatment to about 3.5 grains-per-gallon or softer and keep the softener charged with salt.

· Tools: Manufacturer-approved deliming product (per label), Chemical-resistant gloves and eye protection, Water-hardness test · Source: CMA EAH/EC Owner's Manual (de-liming agents are highly caustic; must be done by a qualified chemical specialist; water softening to 3.5 gpg)

Stop and call a qualified technician if:
Repair or replace? A gasket, coil cleaning, or a simple part is almost always worth fixing. Weigh replacement when the unit needs a compressor or sealed-system repair and is roughly 8–10+ years old, or when repeated service calls approach the cost of a new unit. Compare current commercial dishwashers →

Related commercial dishwasher problems

Frequently asked questions

Why is my commercial dishwasher leaking?

Water on the floor or out the door is usually an owner-level cause: an overflowing/clogged scrap accumulator or drain, a missing or loose end plug/wash-arm cap, too much detergent (foam-over), or the machine not sitting level. Check the scrap accumulator and drain first, look for a missing wash-arm end plug in the scrap tray, cut back detergent if it's foaming, and confirm the machine is level with a slight tilt to the rear. Water leaking from the fill solenoid, drain seal, or internal plumbing while the machine is off is a technician repair.

When should I call a technician instead of fixing it myself?

Call a licensed technician for anything involving the sealed system, refrigerant, gas, or high-voltage wiring — for example: Leaking fill/water solenoid, drain seal, or internal plumbing. These are diagnostic-only for an operator.

Is it worth repairing or replacing?

Simple fixes (gaskets, coil cleaning, a single part) are worth repairing. Consider replacing when it needs a compressor or sealed-system repair and is 8–10+ years old, or when repeat service calls near the price of a new unit.

Sources