Dishwasher Not Draining Completely? (When It’s Normal vs. a Problem)

Quick Answer: A thin layer of water (1/4 inch or less) at the bottom of your dishwasher is completely normal — it keeps the seals moist. If you have more than that, the most common cause is a partially clogged filter that slows drainage.

Noticed some water sitting at the bottom of your dishwasher after a cycle? Before you panic, there’s something important to know: dishwashers are designed to retain a small amount of water.

This guide helps you determine if what you’re seeing is normal operation or an actual drainage problem that needs fixing. According to Energy Star, modern dishwashers are designed to be water-efficient, which includes retaining a small amount of water.

Is Standing Water Normal?

Yes, some water is normal. Here’s why:

The seals and gaskets need to stay moist to prevent cracking
The drain pump primes better when not completely dry
A water seal prevents sewer gases from entering through the drain

How to tell the difference:

Water Level	Status	Action
Barely covers tub floor (1/4” or less)	Normal	No action needed
Visible pooling but under 1”	Borderline	Monitor, clean filter
1” or more of standing water	Problem	Troubleshoot now

Quick test: Stick your finger in the water. If it doesn’t reach your first knuckle when touching the bottom, you’re probably fine. If water is above your knuckle, something is restricting drainage.

Common Causes of Partial Drainage

When your dishwasher drains some water but not all, these are the likely culprits:

1. Partially Clogged Filter

The filter can let some water through while restricting flow. A partial clog drains slowly, and the cycle may end before all water exits.

Signs:

Water drains slowly during the cycle
More water left than usual
Gradually getting worse over time

Fix: Remove and thoroughly clean the filter. Scrub with a brush — a quick rinse isn’t enough. Check the sump area for debris that passed through.

2. Restricted Drain Hose

A drain hose doesn’t have to be completely blocked to cause problems. A partial kink or internal buildup can slow drainage.

Signs:

Drainage is sluggish but works eventually
Problem appeared after moving items under the sink
Hose looks fine but feels stiff

Fix: Straighten any kinks. If the hose is old, disconnect and flush with water to clear internal buildup. Replace if heavily restricted.

3. Air Gap or High Loop Issues

If your air gap is partially clogged, or the high loop has sagged, water may not drain fully.

Air gap signs:

Water spurts from air gap during cycle
Air gap looks clean but interior is restricted

High loop signs:

Drain hose no longer reaches countertop level
Hose has slipped down over time

Fix: Clean inside the air gap with a brush. Re-secure the drain hose at proper height for high loop installations.

4. Garbage Disposal Drain Buildup

Grease and food accumulate where the dishwasher connects to the disposal, narrowing the drain path.

Signs:

Disposal itself drains slowly
Dishwasher issues coincide with disposal issues

Fix: Clean the disposal thoroughly. Check the dishwasher inlet inside the disposal for buildup.

5. Weak Drain Pump

An aging pump may not have enough power to fully evacuate water, especially against resistance from clogs or hose restrictions.

Signs:

Pump sounds normal but drainage is weak
Problem gets worse over time
Dishwasher is 8+ years old

Fix: This often indicates the pump is wearing out. See our drain pump guide for testing and replacement options.

Step-by-Step Fix

Follow this order to address partial drainage:

Measure the water level — Confirm there’s actually more than normal (over 1/4 inch)
Clean the filter thoroughly — Remove both parts if you have a two-part filter. Scrub with a brush, don’t just rinse.
Check the drain hose — Look under the sink for kinks or crushed sections. Verify high loop position.
Clean the air gap (if you have one) — Remove the cap and clear any debris.
Run the garbage disposal — Clear any buildup at the dishwasher connection.
Run a test cycle — Use a short cycle and check the water level after.
If still not draining completely — The pump may be weak, or there’s a deeper restriction.

What If Water Level Varies?

Does the amount of leftover water change between cycles? This can indicate:

More water on heavy cycles:

Normal — heavy cycles use more water
Filter may be near its capacity
Clean filter more frequently

More water when disposal is full:

Disposal backup affecting dishwasher drainage
Always run disposal before dishwasher

Comes and goes randomly:

Check valve may be sticking intermittently
Pump could be failing (works sometimes, not always)

How Much Water Is Too Much?

To help you gauge:

Approximate Level	Typical Cause
Film of water	Normal
1/4 inch	Normal to borderline
1/2 inch	Filter needs cleaning
1 inch	Definite blockage somewhere
2+ inches	Serious drainage problem

If you consistently see 1/2 inch or more, you have a drainage restriction even if the dishwasher still “works.” Addressing it now prevents complete failure later.

Preventing Partial Drainage

Clean filter every 2-4 weeks — Don’t wait until you notice problems
Scrape dishes well — Large particles accumulate quickly
Run disposal before dishwasher — Clear the drain path
Check the hose annually — Verify it’s still properly positioned
Use proper detergent — Too much creates residue that slows drainage

When to Worry

Contact a technician if:

Water level keeps increasing despite cleaning filter
You hear grinding or no sound during drain cycle
Water appears under or around the dishwasher
The problem appeared suddenly (may indicate pump failure)

FAQ

Is it normal to have a little water in the bottom of a dishwasher?

Yes. A thin layer of water (1/4 inch or less) at the bottom is normal and by design. This water keeps the seals moist and helps the pump prime. Only be concerned if water level is above 1/2 inch or increasing over time.

Why is my dishwasher not fully draining?

The most common cause is a partially clogged filter that allows some water through but restricts full flow. Other causes include a kinked drain hose, air gap blockage, or weak drain pump. Clean the filter first — this fixes most partial drainage issues.

How much standing water is normal in a dishwasher?

About 1/4 inch covering the bottom of the tub is normal. You should barely be able to see it. If water pools visibly or is deep enough to cover the filter housing, that’s more than normal and indicates a drainage restriction.

Why does my dishwasher leave dirty water?

If the remaining water looks dirty, the filter may be extremely clogged — it’s passing dirty water rather than trapping debris. Or the dishes weren’t scraped well and excess food is overwhelming the filter. Clean the filter thoroughly and scrape dishes better before loading.

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