How to Replace a Maytag Dishwasher Drain Valve and Check Valve Assembly

The drain valve (check valve) on a Maytag dishwasher prevents water from flowing back into the tub after the drain pump has evacuated it. When this valve fails, you may notice dirty water returning to the tub between cycles, water in the bottom of the tub when you open it in the morning, or a sewer smell coming from the dishwasher when it has been idle. On Maytag dishwashers, the check valve is integrated into the drain pump assembly or located in the drain hose connection at the pump outlet, depending on the model year.

This repair is closely related to the drain pump replacement because the check valve is accessed through the same path. On many models, replacing the entire drain pump (WPW10348269, $35-$65) is more practical than trying to replace only the check valve flapper, because the pump kit includes a new integrated check valve.

Before You Start

• Tools needed: 1/4-inch hex driver, pliers (for spring clamps), Torx T20 driver, towels, shallow pan
• Parts needed: Check valve flapper ($8-$15) or complete drain pump assembly WPW10348269 ($35-$65) which includes integrated check valve
• Time required: 20-35 minutes
• Difficulty: Beginner to Intermediate
• Safety warning: Disconnect power at the circuit breaker and turn off the water supply. Residual water will be present when you access the drain system components.

Step-by-Step Instructions

Step 1: Confirm the check valve is the issue

The diagnostic test for a failed check valve is simple. Run a cycle and let it complete. Open the door. The tub should be empty except for the small amount of water that normally remains in the sump below the filter. Close the door and wait 2-4 hours. Open again. If water has risen in the tub (or the tub is now partially full), water is flowing backward through the drain system. This is either a failed check valve or an improperly routed drain hose without a high loop. Check the drain hose routing first (must loop to underside of countertop) before replacing the valve.

Step 2: Remove the lower access panel

Disconnect power at the breaker. Turn off the water supply. Remove the lower access panel (kick plate) secured by two 1/4-inch hex screws along the bottom. Place towels and a shallow pan under the drain pump area (left side of the tub bottom).

Step 3: Locate the check valve

On most current Maytag models, the check valve is integrated into the drain pump body. The impeller spins in one direction for drainage and the check valve flapper prevents reverse flow when the pump stops. On some older models, there is a separate check valve housing between the pump outlet and the drain hose. Identify which configuration your model has by examining where the drain hose connects to the pump.

Step 4: Access the check valve

For integrated check valve (inside pump body): Disconnect the wire harness from the pump. Remove the drain hose from the pump outlet (squeeze spring clamp, slide back, pull hose free). Twist the pump counter-clockwise to release from the sump housing. Pull free. Look into the pump outlet or inlet for the check valve flapper. It is a rubber or plastic disc that should swing freely in one direction and seat firmly in the other.

For external check valve (separate housing): Squeeze the spring clamps on both sides of the check valve housing. Pull the hoses off each end. Remove the housing. Open it (usually twist-apart or snap-apart) to access the flapper disc inside.

Step 5: Inspect and replace the check valve flapper

The flapper should be pliable, clean, and seat completely flat against its rim when in the closed position. Common failure modes: warped flapper that does not seat (allows backflow), debris stuck under the flapper preventing closure, or a degraded flapper that has cracked or become rigid. If the flapper is damaged, replace it. If the entire pump housing is worn or the flapper seat is damaged (grooved, corroded), replace the complete pump assembly because a new flapper will not seal against a damaged seat.

Step 6: Reassemble and verify flow direction

Install the new flapper or new pump. Ensure the check valve orientation is correct: it must allow flow AWAY from the tub and block flow TOWARD the tub. If installed backward, the dishwasher cannot drain at all. Reconnect the drain hose with spring clamp. Reconnect the wire harness. Verify the pump is locked into the sump housing (twist clockwise until it clicks on bayonet-mount models).

Step 7: Test the repair

Reinstall the lower access panel. Restore water and power. Run a complete Normal cycle. After the cycle completes and the drain pump finishes, verify the tub is empty. Close the door and wait 1-2 hours. Open and check that no water has returned to the tub. If the tub remains dry, the check valve repair is successful.

Step 8: Address drain hose routing (complementary fix)

Even with a working check valve, improper drain hose routing can cause backflow through siphoning. Verify the drain hose has a high loop secured to the underside of the countertop with a hose clamp. The highest point of the hose loop must be above the flood level of the sink (above the rim of the sink basin). This creates an air break that prevents siphoning regardless of check valve condition. Consider this step as complementary insurance to the valve replacement.

Understanding Maytag Drain System Design

Maytag dishwashers use a separate drain pump motor (not a reversing circulation pump), which provides more reliable drainage but means the check valve is the sole mechanical barrier against backflow when the pump is idle. The stainless steel chopper grinds food waste before it reaches the drain path, which reduces debris-related check valve failures compared to filter-only systems. However, grease and soap film can accumulate on the check valve flapper over years, eventually preventing it from sealing completely.

The drain pump part number WPW10348269 is shared across Whirlpool, Maytag, and KitchenAid dishwashers. When the check valve is integrated into this pump, replacing the entire pump is often the most practical approach because the labor to access it is the same either way, and the pump only costs $35-$65.

Troubleshooting Persistent Backflow

If water continues to return to the tub after valve replacement:

• Verify drain hose high loop is properly installed and secured
• Check if the garbage disposal connection is below the flood level of the sink. If so, water from the sink can flow backward into the dishwasher drain hose
• Inspect the air gap device (if installed) for blockages. Remove the chrome cap and clear any debris from the air gap body
• Verify the check valve orientation is correct (allows flow away from tub only)

When to Call a Professional

Contact a professional if:

• Backflow continues despite check valve replacement and correct hose routing, suggesting a complex plumbing issue under the sink
• The drain pump housing is cracked, causing leaks in addition to backflow
• You notice sewer gas smell from the dishwasher that persists after fixing the backflow, which may indicate a separate venting issue in your drain plumbing

Cost Comparison: DIY vs Professional

Need Professional Help?

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• Dishwasher repair cost guide

FAQ

Q: How do I know if it's the check valve or the drain hose causing backflow? A: Disconnect the drain hose from the garbage disposal or tailpiece under the sink and cap it temporarily. Run a cycle. If the tub stays empty after completing, backflow is coming through the drain hose from the sink (routing issue, not check valve). If water still returns to the tub with the hose disconnected, the check valve has failed.

Q: Can I clean the check valve instead of replacing it? A: Yes, if the flapper is intact but has debris preventing it from seating. Remove the valve, clean the flapper and seat with warm soapy water, and verify the flapper seats flat with no gaps. However, if the flapper is warped, cracked, or rigid from age, cleaning will not restore its sealing ability.

Q: Is the check valve covered under Maytag's warranty? A: The check valve (whether integrated into the drain pump or separate) is covered under the standard 1-year warranty. It is not part of the 10-year limited warranty which covers only the stainless steel tub, racks, and chopper blade. Given the low cost of the part, this repair is practical even outside warranty.

Q: Why does my Maytag dishwasher smell like sewer between uses? A: A failed check valve allows sewer gas to travel backward through the drain hose into the dishwasher tub. Replacing the check valve and ensuring proper drain hose routing (high loop) eliminates this path. Running a hot cycle with vinegar after the repair flushes any residual odor from the tub and pump housing.

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