Dishwasher Water Backing into Kitchen Sink

This page groups common situations where dishwasher drain water shows up in the kitchen sink—for example the sink filling while the appliance runs, dirty water rising during drain, or suds appearing in the basin. Some backups occur only at certain points in the cycle (drain, end of cycle, overnight) or only with hot cycles; others begin after an installation or a parts change. Use the group that best matches when the problem happens and what changed recently, then open the closest article.

See the broader category for related sink and food-waste topics: Kitchen Sink & Food Waste Plumbing

Basic dishwasher-to-sink backup symptoms

Symptoms where dishwasher discharge appears directly in the sink basin.

• Dishwasher drains into sink

  Explains common causes when dishwasher discharge flows back into the sink, including blocked traps, shared drains, and venting issues.

• Sink fills when dishwasher runs

  Helps pinpoint whether the problem is a partial clog, an incorrect hose routing, or a downstream obstruction.

• Dirty water backing into sink

  Focuses on why greywater or soiled dishwasher water returns to the basin and what to check first to reduce contamination risk.

• Sink overflows during dishwasher cycle

  Outlines immediate safety steps and likely plumbing faults that let dishwasher flow cause an overflow at the sink.

Only happens at specific times in the cycle

Problems that show up only during certain parts of the dishwasher program or under particular cycle conditions.

• Backup only when dishwasher drains

  Describes why backups occur during the drain phase and how failing pump, hose clogs, or shared waste lines contribute.

• Backup only when dishwasher finishes

  Examines end-of-cycle drains and how final draining or air gaps can allow water to reverse into the sink.

• Sink fills when dishwasher drains overnight

  Looks at slow drains, partial blockages, and check-valve issues that reveal themselves during long idle periods.

• Backup only when dishwasher runs long

  Considers how longer wash programs can expose slow clogs, pump overheating, or thermal-related expansion in traps.

• Sink fills only on hot cycles

  Points to temperature-sensitive failures such as softened debris, warped hoses, or thermal-driven venting problems.

After installs or changes

Backups that start immediately after installing a dishwasher, replacing a disposal, or altering the drain hose.

• Sink backs up after installing dishwasher

  Checklist for common installation mistakes—incorrect hose height, missing air gap, or improper connection to the waste line.

• Backup after replacing disposal

  Discusses errors during disposal replacement that can block or misroute dishwasher discharge into the sink.

• Dishwasher drain hose installed wrong

  Shows how low loops, kinks, or missing high loops/air gaps cause siphoning or backflow into the sink.

After repairs, outages, or winter events

Situations where backups appear after plumbing work, disruptions to the system, or seasonal shut-downs.

• Backup after plumbing repair

  Guides checks for disturbed traps, reconnected vents, or temporary blockages left after repair work.

• Backup after city outage

  Explains how mains pressure changes or sewer backups during outages can let dishwasher flow return to fixtures.

• Sink fills after winterization

  Covers issues caused by winterizing or de-winterizing lines, such as trapped air pockets or dislodged debris.

Clues: gurgling, suds, or filter issues

Secondary symptoms that help narrow the cause of dishwasher-to-sink backups.

• Dishwasher causes kitchen sink gurgling

  Explains how trapped air, partial clogs, or venting problems produce gurgling noises when the dishwasher runs.

• Sink fills with suds from dishwasher

  Outlines why wrong detergent, overuse, or a returning flow of soapy water leads to suds in the sink basin.

• Sink backs up when dishwasher filter clogged

  Describes how a clogged dishwasher filter or pump inlet can slow drainage and push water back into the sink.

All Articles in This Cluster

• Dishwasher drains into sink
• Sink fills when dishwasher runs
• Dirty water backing into sink
• Sink overflows during dishwasher cycle
• Backup only when dishwasher drains
• Backup only when dishwasher finishes
• Sink fills when dishwasher drains overnight
• Backup only when dishwasher runs long
• Sink fills only on hot cycles
• Sink backs up after installing dishwasher
• Backup after replacing disposal
• Dishwasher drain hose installed wrong
• Backup after plumbing repair
• Backup after city outage
• Sink fills after winterization
• Dishwasher causes kitchen sink gurgling
• Sink fills with suds from dishwasher
• Sink backs up when dishwasher filter clogged