Dishwasher Not Draining? Check These Before You Call
Water sitting in the bottom after a cycle has a short list of causes, and they go in order: a clogged filter or sump basket, a blocked air gap or missing high loop, a kinked drain hose, the disposal knockout plug (the classic after a new disposal), or a clog in the shared sink drain. Work the list top to bottom and most homeowners find it before the plumber arrives.
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Safety first: if you smell gas, see water near electrical outlets or your panel, or sewage is contacting living areas, get people clear first. For a gas smell, leave and call 911 or your gas utility's emergency line before anything on this page.
- !Water is leaking onto the floor and toward the dishwasher's electrical connection or a nearby outlet: cut power at the breaker
- !The standing water is hot and you need to reach in: let it cool, and switch the unit off at the breaker first
- !Dirty water is backing up into the kitchen sink and rising rather than draining: stop running water, that is a drain blockage
- !A burning smell from the dishwasher during a cycle: the drain pump may be straining against a blockage, shut it off
- !Sewage odor coming up with the backup, pointing at a deeper drain problem
- ✓Run the disposal first: if the dishwasher drains into a disposal, a few cups of food in there will block the dishwasher. Run it with cold water, then retry the dishwasher drain
- ✓Bail the standing water out with a cup and sponge, then pull and rinse the filter or sump basket at the bottom: trapped food and glass are the most common cause
- ✓Check the drain hose under the sink for a kink or pinch, and confirm it loops up high (the high loop or air gap) before going down to the drain
- ✓If you have an air gap (the small cylinder on the sink deck), pop its cap and clear any food debris packed inside it
- ✓Check whether the kitchen sink itself drains: if the sink is also slow, the clog is in the shared drain, not the dishwasher
- →The filter is clean, the hose is clear, and water still will not drain: the drain pump or its impeller has failed and needs an appliance repair
- →A brand-new disposal was just installed and the dishwasher stopped draining: the disposal knockout plug was likely left in place
- →Dirty water backs up into the sink whenever the dishwasher drains: the branch drain serving both is clogged and needs snaking
- →You hear the pump motor hum but no water moves, even with a clean filter and hose
- →Repeated backups after clearing, which point at a deeper or recurring clog in the line
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The drain checklist, in order
Start with the filter and sump basket at the bottom of the tub, because it is the most common cause and the easiest to check. Bail out the standing water, lift out the cylindrical filter (usually a quarter turn), and clear the food, seeds, glass chips, and grease packed into it and the sump below. A clogged filter is the number one reason a dishwasher holds water, and many homeowners have never cleaned theirs.
Next, the drain path geometry. The dishwasher's drain hose must rise to a high loop under the counter or pass through an air gap on the sink deck before dropping to the drain; that loop is what stops dirty sink water from siphoning back in and what lets the pump push water out. If the hose sags or the air gap is packed with debris, draining stalls. Pop the air gap cap and clear it, and confirm the hose is looped up, not lying flat. Then check the whole hose run for a kink, especially where it was pushed back during a recent repair.
The disposal connection is the next stop, and it has a famous failure mode. When a disposal is brand new, it ships with a sealed knockout plug in the dishwasher inlet that must be punched out during install. Skip that step and the dishwasher has nowhere to drain. If your dishwasher stopped the day a new disposal went in, the plug is almost certainly still there, blocking the line. Finally, if the kitchen sink itself drains slowly, the clog is in the shared drain downstream, not the dishwasher, and that is a different fix covered in kitchen sink not draining.
Backing up into the sink is a different problem
There is a sharp line between a dishwasher that will not drain and dirty water backing up into the sink when the dishwasher runs. The first is usually inside the dishwasher (filter, pump, hose). The second is not a dishwasher problem at all: it means the branch drain that both the sink and dishwasher share is clogged downstream of where they join. The dishwasher pumps water out, the clog blocks its path, and it surfaces in the nearest open drain, the sink basin.
You can confirm it: if the sink drains slowly or backs up on its own, independent of the dishwasher, the shared line is the culprit. Cleaning the dishwasher filter will not help here, because the dishwasher is working fine. The fix is clearing the branch drain, and if grease and food have built up over years, that is a snaking job. A backup that rises and lingers, or carries a sewer odor, can point further downstream toward the main, in which case our drain cleaning pricing covers the methods.
What each fix costs
The DIY checks (filter, air gap, hose kink, running the disposal, punching the knockout plug) cost nothing and resolve most drainage complaints. When a plumber or appliance tech comes out, a service visit to diagnose and clear the drain path runs $100 – $250, including the trip charge and clearing the filter, hose, air gap, or knockout plug.
If the backup is in the shared sink drain, snaking the branch line runs $150 – $400 depending on how far in the clog sits and how stubborn it is. A failed drain pump is an appliance repair rather than a plumbing one and runs higher with parts and labor; on an older dishwasher, that cost is weighed against replacement, and our dishwasher installation pricing frames that comparison. A recurring backup that survives snaking points deeper into the line and is worth a camera look before you keep paying to clear the same spot.
Keep it draining
Two habits prevent most no-drain calls. Scrape plates before loading so large food, seeds, and especially fibrous scraps do not pack the filter, and clean the filter itself every month or two: a two-minute rinse that owners routinely skip until water stands. Run the garbage disposal before starting the dishwasher so the shared drain is clear, since a full disposal blocks the dishwasher's only exit.
When anything under the sink is serviced (a new disposal, a new faucet, a trap repair), check three things afterward: the drain hose still loops high, the air gap is clear, and on a new disposal the knockout plug was punched out. Those are exactly the items a hurried install leaves wrong, and they show up as a dishwasher that suddenly will not drain the next time you run it.
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