Dishwasher Smells? UK Engineer’s Fix Guide 2026

01Why does my dishwasher smell?

Dishwashers get a raw deal in most UK households. The assumption is that an appliance which sprays hot soapy water around its own interior should clean itself. In practice, dishwashers are one of the dirtier appliances inside the kitchen, and the single most common cause of complaints is a bad smell that lingers between cycles or drifts into the kitchen when the door is opened.

The good news is that the cause is almost always one of a small number of problems, all of which are user-fixable in minutes without a callout. The guide below works through the causes in the order our engineers check them.

02What does the smell tell you about the cause?

The character of the smell is the fastest way to narrow down the cause. Work out which description below best matches your dishwasher and start there.

03Cause 1: Is the filter blocked or neglected?

At the base of every dishwasher tub is a filter, usually a two-part system with a coarse outer mesh and a fine inner cup. Its job is to catch food debris during the wash cycle so particles are not pumped back onto the dishes. Cleaning the filter is the single most important dishwasher maintenance task, and the one most UK households never do.

A neglected filter traps food debris that breaks down over weeks and months. The bacteria and biofilm that grow on the trapped debris are the direct cause of the musty, sour or rotting-food smell that most households describe. Cleaning the filter thoroughly removes the smell at source and the result is usually noticeable within one or two subsequent cycles.

How to clean the filter properly

1. Pull the lower rack out fully. The filter sits in the centre or offset to one side at the base of the tub. On most UK dishwashers it is a cylindrical unit with a twist-lock mechanism.
2. Twist anticlockwise a quarter turn and lift the filter out. On two-part filters, the outer coarse mesh lifts free once the inner cup is removed, and the inner unscrews.
3. Rinse both parts under a hot tap and scrub with a soft brush. An old toothbrush is ideal. Pay particular attention to the mesh, which can clog invisibly with fine debris, grease and limescale.
4. Soak heavily soiled filters in hot soapy water with a splash of white vinegar for 10 to 20 minutes. Then scrub again. The vinegar dissolves grease and limescale that detergent alone will not shift.
5. Shine a torch into the empty filter housing and check the sump. Clear any debris sitting in the housing itself with a cloth or kitchen paper before refitting.
6. Refit the filter and twist clockwise to lock. A click or firm resistance indicates it is properly seated. A loose filter lets food debris bypass the filter entirely and reach the pump, which causes new faults.

Our full dishwasher cleaning guide covers filter maintenance frequency, when to replace a damaged filter, and the wider maintenance routine. Replacement filters are inexpensive (£15 to £35 typically) and model-specific. Available via our spare parts service.

04Cause 2: Is the door seal or door channel dirty?

The rubber door seal around the top and sides of the tub opening, and the metal channel at the bottom of the door where it meets the tub when closed, are the two areas of the dishwasher that the wash cycles never properly reach. The spray arms direct water at the dishes and across the tub walls, but they cannot reach the fold of the door seal or the bottom door channel. Food particles, grease and biofilm build up here almost invisibly and are the second largest single contributor to bad dishwasher smells.

How to clean the door seal

1. Open the dishwasher fully. The rubber door seal runs around the top and sides of the tub opening. Pull it back gently in each area and inspect the fold on the inside for trapped food, grease and dark grime.
2. Wipe the seal thoroughly with a cloth dampened with warm soapy water. For stubborn buildup, use a cloth with white vinegar or a mild bleach solution (three parts water to one part bleach).
3. Pay particular attention to the bottom corners of the seal. This is where debris collects by gravity and where the worst smells usually originate.
4. Dry the seal with a clean cloth afterwards. Leaving the seal damp encourages new mould growth.

How to clean the door channel

1. Open the door fully and look at the bottom edge of the door and the corresponding channel on the tub. This is a dead zone that no water reaches during any cycle.
2. Wipe out any accumulated debris with a damp cloth. Food particles that fall from dishes as they are loaded or unloaded accumulate here indefinitely.
3. Use a soft brush or a wooden toothpick for the recessed areas. Metal implements can scratch the finish or damage the hinge seal.

This step alone often dramatically reduces a persistent dishwasher smell, particularly in households that have cleaned the filter but still find the odour persists. The door channel is the area most people never think to check.

05Cause 3: Are the spray arm jets blocked?

Dishwashers have two or three spray arms (bottom, middle and often top) that rotate and direct hot soapy water at the dishes during the wash cycle. Each arm has a series of small jets that direct water at specific angles. When these jets get blocked with food debris or limescale, the wash performance drops noticeably, and food residue that would normally be flushed away stays on the dishes and in the tub, contributing to a persistent smell.

How to clear blocked spray arm jets

1. Lift or unclip each spray arm. The bottom arm typically pulls straight up. The middle and top arms usually unclip via a central hub or unscrew.
2. Hold each arm up to the light and inspect every jet. Any jet that is not a clear pinhole is partially or fully blocked.
3. Use a wooden toothpick to gently clear each blocked jet from the outside. Push the blockage back through and flush it out with running water. Never use metal wire or a metal pick, which can enlarge the jets and change the spray pattern permanently.
4. Run water through the arm to flush loosened debris. Hold the arm under a tap and let water run through from the central hub.
5. Reassemble. Confirm the arm spins freely by hand after refitting.

Blocked spray arms are a particularly common issue in UK hard water areas (south-east England, East Anglia, parts of the Midlands) where limescale builds up on the jets over time. Running an occasional descaling cycle helps prevent recurrence. See our guide to descaling in hard water areas, which applies the same principles to dishwashers.

06Cause 4: Is a sewer smell coming up through the drain?

A rotten-egg, sulphurous or sewer-like smell from a dishwasher is almost always caused by sewer gases coming back up the drain hose from the household waste system, rather than anything inside the appliance itself. This is a plumbing problem, not an appliance fault, and cleaning the filter and spray arms will not fix it.

How to diagnose a drain smell

How to fix a drain smell

Most drain smells are fixed by correcting the drain hose routing. Pull the dishwasher forward and inspect the hose. If it runs directly to the floor-level waste without being looped up first, lift the hose to the correct height (60 to 90cm) and secure it. Most dishwasher installation kits include a plastic hook or clip for this purpose. If the kit is missing, any plumbing supplier sells them for a few pounds.

If the household waste trap has dried out because the dishwasher has not been used for a while, running a few cycles usually refills the trap and the smell clears. If the problem persists, the household waste plumbing may need investigation by a plumber rather than an appliance engineer.

07Cause 5: Is there stagnant water in the tub?

A small amount of water is left in the base of the tub between cycles on most modern dishwashers. This is normal and intentional. It prevents the seals drying out and cracking, keeps the pump from running dry on the next cycle start, and helps the detergent dispenser function correctly.

If the dishwasher has not been used for a week or more, this residual water becomes stagnant and develops an unpleasant pond-like smell. The fix is simple: run a hot empty maintenance cycle, which flushes the standing water and replaces it with fresh.

If the residual water level is unusually high (more than around 1cm deep), the drain may be partially blocked and the cause is drainage rather than hygiene. See our dedicated guide to a dishwasher not draining for the full diagnostic sequence. A partial drain fault often presents as a smell complaint before it presents as a drain complaint.

08How do I stop my dishwasher smelling again?

Most dishwasher smells return because the underlying maintenance routine was never set up. A small amount of ongoing attention (around 30 minutes a month in total) prevents almost all recurrence.

• 
  Rinse the filter weekly under a hot tap. Deep clean monthly with a brush and hot soapy water.
• 
  Wipe the door seal and door channel after every heavy load. Both are dead zones that build up grime fast.
• 
  Run a hot maintenance wash monthly (vinegar plus bicarbonate, or a commercial dishwasher cleaner). The hottest cycle, no detergent, no dishes.
• 
  Scrape plates before loading but do not pre-rinse to spotless. Modern detergents need food residue to work against, and over-rinsing actually reduces cleaning performance.
• 
  Keep dishwasher salt and rinse aid topped up, even when using 3-in-1 tablets. Limescale is a major cause of spray arm blockages in UK hard water areas.
• 
  Check the drain hose is looped up to 60 to 90cm above the floor before it connects to the household waste. This prevents sewer gas tracking back.
• 
  Leave the door slightly ajar between cycles so the interior can dry out. A damp sealed tub encourages mould and biofilm growth.
• 
  If the dishwasher will not be used for more than a week, run a quick hot empty cycle before next use to flush the standing water.

09When should I call an engineer?

Cleaning the filter, door seal, spray arms and running a maintenance wash are all jobs anyone can do. Beyond that, the balance tips towards an engineer, partly for safety and partly because the next steps need the machine opened up or involve the household plumbing.

If the household waste plumbing is the cause and correcting the drain hose routing has not fixed it, the wider plumbing may need investigation by a qualified plumber rather than an appliance engineer. Our Find an Engineer service covers nationwide dishwasher diagnosis across all major UK brands. Door seal replacement typically costs £30 to £60 for the part plus £80 to £150 for labour on a qualified repair.

10Safety notice

11Frequently asked questions