How to Replace the Drain Valve on a Whirlpool Dishwasher: Check Valve and Backflow Fix

If you open your Whirlpool dishwasher between cycles and find dirty standing water in the bottom — or notice a sewer-like smell when you open the door — the drain check valve has failed. The check valve is a one-way flapper or ball valve built into the drain pump outlet or drain hose assembly that prevents waste water from flowing back into the tub after the drain cycle completes. When it sticks open or the flapper deteriorates, water (and odor) flows backward from the sink drain into the dishwasher.

This is different from a failed drain pump (which causes water to never drain in the first place). With a check valve failure, the dishwasher drains fine during the cycle, but water slowly siphons back in afterward.

Before You Start

• Tools needed: 1/4" hex nut driver, channel-lock pliers, Torx T20 driver (if pulling unit out), towels, flashlight, bucket
• Parts needed: Drain check valve (~$12-$25) or complete drain pump assembly with integrated check valve ($45-$75)
• Time required: 20-40 minutes depending on valve location
• Difficulty: Beginner to Intermediate
• Safety warning: Disconnect power at the circuit breaker. Drain water will contain food debris and bacteria — wear gloves and clean up with disinfectant.

Step-by-Step Instructions

Step 1: Confirm Backflow Is the Problem

Differentiate between drain failure and check valve failure:

• Drain pump failure (F5E2): Water never leaves the tub at end of cycle. Pump does not hum.
• Check valve failure: Dishwasher drains completely at end of cycle, but water returns over the next few minutes/hours. You find dirty water when you open the door long after the cycle ended.
• Air gap or high loop issue: If you have no air gap and no high loop in the drain hose, water can siphon back through the drain hose without any valve failure. Install a high loop first.

To confirm: run a drain cycle and verify the tub empties completely. Then wait 30 minutes without opening the door. If water has returned, the check valve is failing.

Step 2: Identify Your Check Valve Type and Location

Whirlpool dishwashers use the check valve in one of these locations:

• Integrated into drain pump housing: The check valve is built into the pump outlet. Replacing it means replacing the entire drain pump assembly (W10876537). This is common on newer WDT/WDF models.
• Inline valve in drain hose: A separate check valve body is installed in the drain hose between the pump and the sink connection. This is more common on older models.
• At the air gap or disposal connection: Some installations place a check valve at the sink-side termination of the drain hose.

Remove the kick plate (two 1/4" hex screws) and trace the drain hose from the pump outlet to where it exits the dishwasher cavity. Look for a separate valve body in the hose path.

Step 3: Disconnect Power and Drain Residual Water

Turn off the circuit breaker. If there is standing water in the tub, place towels under the kick plate area and have a bucket ready. The drain hose will release trapped water when disconnected.

Step 4: Replace an Inline Check Valve

If your valve is a separate inline component:

1. Locate the valve body in the drain hose run — it is usually a cylindrical plastic fitting between two hose sections, held by spring clamps
2. Note the flow direction arrow on the valve body — it should point AWAY from the dishwasher (toward the sink)
3. Release the spring clamps on both sides using pliers
4. Pull the hose off both ends of the old valve
5. Install the new valve with the arrow pointing toward the sink
6. Reconnect hoses and slide spring clamps back over the connections
7. Verify the connections are secure — a loose spring clamp here will cause a leak during drain

Step 5: Replace a Pump-Integrated Check Valve

If the check valve is built into the drain pump (no separate valve visible in the hose):

• You need to replace the entire drain pump assembly (W10876537)
• This requires pulling the dishwasher out, tipping it back, and removing the pump from the sump underneath
• Follow the drain pump replacement procedure (pull unit out, tip back, disconnect pump connector, release bayonet mount or Torx T20 screws, swap pump, reconnect)
• The new pump will have a fresh integrated check valve

Step 6: Verify the Drain Hose Has Proper High Loop or Air Gap

Even with a working check valve, the drain hose installation must prevent siphoning:

• Air gap (required in most California installations): The drain hose goes UP to the air gap device on the countertop, then back DOWN to the disposal. The air break prevents any backflow.
• High loop: If no air gap, the drain hose must loop to the highest point under the counter (typically attached to the underside of the countertop with a strap or bracket) before descending to the disposal.
• Neither: If the hose runs straight from the dishwasher to the disposal at the same height or lower, water WILL siphon back regardless of the check valve. Install a high loop at minimum.

Step 7: Test the Repair

Replace the kick plate. Restore power. Run a Normal cycle to completion. After the cycle ends:

1. Verify the tub is empty (drain pump worked)
2. Close the door and wait 30 minutes
3. Open the door — the tub should still be dry
4. Smell test — no sewer odor should be present
5. If water has returned, check your high loop or air gap installation. If those are correct, the pump-integrated check valve may be the type you need to address.

Why Backflow Happens and Prevention

When to Call a Professional

• The backflow persists despite a new check valve and proper high loop — there may be a drain line blockage downstream that creates positive pressure pushing water back
• You cannot identify whether your valve is inline or pump-integrated
• The drain pump itself needs replacement and you cannot safely pull/tip the unit
• There is sewage backup from the main drain line — this is a plumbing issue beyond the dishwasher itself

Cost Comparison: DIY vs Professional

Need Professional Help?

• Dishwasher repair service
• Whirlpool appliance repair
• Dishwasher repair cost guide

FAQ

Q: Why does my Whirlpool dishwasher smell like sewage when I open the door? A: Sewer gas travels from the drain line back through the drain hose into the tub when the check valve fails or there is no air gap/high loop. The smell is most noticeable when the dishwasher has been idle for a day or more. Fixing the check valve and ensuring a proper high loop eliminates the odor path.

Q: Is a high loop alone sufficient, or do I need both a check valve AND a high loop? A: A high loop alone is sufficient to prevent gravity siphon (water flowing downhill back into the tub). A check valve provides additional protection against pressure-driven backflow (when the disposal runs or someone drains the sink). For best protection, have both — but a high loop is the minimum requirement.

Q: Can food debris from the disposal get pushed into my dishwasher through backflow? A: Yes. If the disposal runs while the dishwasher drain hose has no check valve and no high loop, disposal waste can be pushed up the hose into the tub. This is both unsanitary and can clog the dishwasher drain pump. Always have either an air gap or a check valve with high loop.

Q: How do I know if my Whirlpool dishwasher has a check valve built into the pump? A: Remove the kick plate and trace the drain hose from where it exits the pump to where it leaves the dishwasher cavity. If there is no separate valve body in the hose (just continuous hose), the check valve is integrated into the pump housing. Most post-2015 WDT/WDF models use the integrated design.

---

Need a certified technician? Book same-day repair →