Dishwasher Won’t Drain? Water in the Bottom — Fix in 20 Minutes (Australia)

Quick answer: Standing water in the bottom of a dishwasher is almost always one of five things, in order of likelihood: a blocked filter or pump impeller (free fix, food debris and broken glass migrate there), a blocked or kinked drain hose, a blocked sink U-bend or air gap (the dishwasher drains into the kitchen sink plumbing — if the sink is slow, the dishwasher backs up), or a failed drain pump. Run the five checks below in order — they’ll find the cause every time. We stock drain pumps, filters and hoses for Bosch, Smeg, F&P, Westinghouse, Samsung, LG, Asko, Miele and more, same-day dispatch from Sydney.

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Before you start — bail the water

A cup or two of clean rinse water sitting in the sump is normal on most dishwashers — that’s there to keep the pump seal wet. You’re chasing murky, food-debris water that won’t go away after a cycle. Scoop it out with a jug into a bucket so you can see the filter, then towel-dry the sump. Power off at the wall before you put hands in.

Check 1: The filter (5 minutes, free) — fixes ~60% of cases

The single biggest cause across every brand we stock. Unscrew the filter basket in the bottom of the tub (turn anti-clockwise, lifts straight out). You’ll usually find a slurry of pea skins, label paper, broken glass and oat sludge. Rinse under the tap, scrub the mesh with an old toothbrush, refit.

While the filter is out, look down into the sump well with a torch. Spin the visible impeller with a finger (power off!) — if it rattles, there’s a foreign object jammed in the chopper or pump. Toothpicks, fruit stickers and bits of cherry stone are the classic culprits.

Refit, run a rinse cycle. Drained = problem solved.

Check 2: The drain hose at the back (5 minutes, free)

Pull the dishwasher out a foot. Two failure modes:

• Kinked under the bench — the corrugated drain hose pinched against the cabinet wall or the gas/water pipes behind. Straighten it, secure with a cable tie so it can’t re-kink.
• Blocked internally — disconnect the hose at the sink end, blow through it. No flow = greasy debris coating the inside (years of accumulated fat). Replacement hose is cheap; cleaning it rarely works long-term.

Check 3: The sink U-bend and air gap (5 minutes, free) — the one people miss

This is the check most DIY guides skip and most plumbers find. Australian dishwashers drain into the kitchen sink plumbing — usually a tee on the sink U-bend, or via an air-gap fitting on the bench. If that pathway is partly blocked, the dishwasher can’t push water out.

Test it: run the kitchen sink tap full-bore for 30 seconds. Does the sink drain fast, or pool? Slow sink = blocked U-bend = blocked dishwasher. Fix the U-bend (unscrew, clean out, refit) and the dishwasher drains again.

Also check: if your install has a high-loop or air-gap, food debris collects at the highest point. Pop the cap, clear it.

Check 4: Confirm the pump is actually trying

Power back on, start a drain cycle, put your ear to the side of the machine. The drain pump should whirr loudly for 30-90 seconds. What you hear tells you the next step:

• Loud whirr, no water moving → pump is running but the path is blocked. Re-check filter, sump, hose, sink.
• Silence → no power to the pump. Could be the pump motor, the control board, or a wiring fault. Less common.
• Low hum then silence → pump motor seized. Replace.

Check 5: Replace the drain pump (30-minute DIY)

If filter, hose and sink are all clear and the pump won’t whirr — or whirrs faintly then stops — the pump is dead.

The swap (universal pattern):

1. Power and water off. Pull the dishwasher out.
2. Lay an old towel down and tip the machine back gently — drains the sump water out the front.
3. Remove the bottom kick panel (2-4 screws) — or, on some Bosch/Smeg models, lay the dishwasher on its back to access the pump from underneath.
4. Disconnect the electrical plug from the pump. Twist the pump off its bayonet mount (most modern brands) or loosen the hose clamps (older designs).
5. Fit the new pump — clip in, electrical plug, snug.
6. Stand up, refit kick panel, push back in, test.

The right part — by brand:

Brand error codes for “won’t drain”

If your dishwasher throws a code rather than just sitting wet, it’s telling you exactly where it gave up:

• Bosch: E22 / E24 / E25 = drain fault (filter blocked, hose kinked, pump dead — work the checks above in order). E15 is different — that’s the anti-flood sensor seeing water in the base tray, not the sump. See our Bosch E15 guide.
• Smeg: flashing end-of-cycle light or “AL05” on newer models = drain fault.
• Fisher & Paykel DishDrawer: F1 = flood detection, drawer won’t drain. Usually a blocked filter or pump.
• Westinghouse / Electrolux: i20 / i30 = water in base or drain timeout.
• Samsung: 5C / 5E / OE = drain error.
• LG: OE = drain error.
• Asko: F2 = drain timeout.
• Miele: F11 = drain blockage (Miele’s signature code — always start with the filter on these).

Same five checks fix all of them — the code just tells you where the machine stopped.

Related guides: dishwasher spare parts guide

FAQs

There’s always a bit of water in the bottom after a cycle — is that normal?

A small puddle (about a cup) in the sump well is normal on most dishwashers — it keeps the pump seal wet between cycles. Murky food-debris water sitting above the filter is not normal — that’s a drain fault.

I cleaned the filter, dishwasher still won’t drain — what next?

Move down the list: drain hose kink, sink U-bend, pump impeller jammed by something the filter let through (broken glass, cherry stones, toothpicks).

My dishwasher drains but very slowly — same fault?

Usually a partly-blocked filter or a fatty drain hose. Clean the filter; if it’s still slow, swap the drain hose — they’re cheap and a decade of grease coats the inside.

Dishwasher won’t drain AND won’t start a new cycle — connected?

Yes. Most dishwashers refuse to start a fresh cycle if there’s standing water in the sump (the float switch sees it and locks the cycle out). Clear the drain fault, the start button works again.

New dishwasher just installed, won’t drain on first cycle?

Almost always an install error — drain hose kinked behind the cabinet, no high-loop fitted, or the knockout plug in the sink-tee never got knocked out. Pull it out, check the plumbing.

Related guides

• Bosch dishwasher E15 error — full guide
• Dishwasher dishes still dirty after a cycle
• Washing machine not draining — full guide
• LG dishwasher OE error

Ready to fix it?

1. Run your dishwasher model through the Oz Appliance Spares Part Finder — model in, exact-fit pump out.
2. Browse by brand: Bosch · Smeg · F&P · Samsung · LG · Westinghouse · Asko · Miele
3. Order before 12pm AEST → ships from our Sydney warehouse same day, Australia-wide.