The Dishwasher Filter, and Why It Explains Both of Your Complaints

How to clean LG dishwasher filter: two complaints, one cause

People ring about two separate things.

*The dishes come out gritty.* And: *there is always a little water in the bottom and it smells.*

More often than not those are the same problem, and the problem lifts out with your fingers.

Why the filter is there at all

A dishwasher does not fill and drain repeatedly the way a washing machine does. It takes a small amount of water and recirculates it, spraying the same water through the arms over and over for most of the cycle.

That only works if what comes off the plates is caught somewhere, and the filter is the somewhere.

Older machines dealt with it by grinding waste up with a hard food disposer. Today's dishwashers filter instead, which is why they are so much quieter — and the trade is that somebody has to empty the filter. That somebody is you, twice a year.

What happens when it packs

Cleaning gets worse. The pump cannot pull clean water through a blocked mesh, so pressure at the spray arms falls and the water it does move is dirtier than it should be.

Draining gets worse. The same restriction sits in the path to the drain pump, so the sump empties slowly and never completely.

And then it smells, because a small amount of water and a filter full of food have been sitting in a warm dark box since Tuesday.

The five minutes

Pull the lower rack out and look at the floor of the tub under the spray arm.

Twist the cylinder counter-clockwise — about a quarter turn on most models — and lift it straight out.

Lift the flat mesh plate underneath it. On some models the two come as one piece; on most they separate.

Warm water and an old toothbrush. Both sides of the mesh. No dishwasher, no bleach, nothing abrasive on the mesh itself.

Look in the sump while it is open. If there is glass, a fruit sticker or a bone chip down there, take it out now — that is exactly what finds its way into a drain pump.

Put it back the other way round. Mesh plate flat first, then the cylinder through it, then turn until it locks. It must lock. A filter that is only sitting there lets everything past it into the pump.

While the racks are out

Two more minutes and you have done the whole appliance.

The spray arms unclip on most models. Hold them up to the light and clear any blocked jet with a toothpick — in hard-water areas the outer holes go first and you notice it as a top rack that never quite gets clean.

The door edge and the bottom seal. A cloth along the lip. That is where the smell people blame on the drain very often actually lives.

How often

Twice a year if plates get a quick rinse before they go in. Monthly if they do not — which is fine, modern detergent is designed for it, but the filter is where that food ends up.

If the machine still holds water after all this, that is a different article and a different job: the drain path, the hose loop, the air gap, or a disposer knockout plug that nobody removed when the machine was installed.