There is a particular family moment when someone unloads the dishwasher, holds a glass up to the light, and says the thing you were hoping nobody would notice. Cloudy. Slightly gritty at the rim. A plate that came out with a fleck of yesterday's rice welded on. And underneath it all, when you open the door on a cold morning, a smell that is not quite anything but definitely not clean.
None of this means the machine is finished. It almost always means the dishwasher has been quietly cleaning your kitchen for two years while nobody cleaned the dishwasher. It takes about twenty minutes to put right, mostly in short bursts while you're in the kitchen anyway.
Start at the bottom: the filter
Pull out the lower rack and find the filter in the floor of the machine — usually a cylinder you twist a quarter turn to release, sitting in a flat mesh plate. Lift both out over the sink, and brace yourself, because the first time is genuinely grim. Rinse them under a hot tap, then work a soft brush and a drop of washing-up liquid into the mesh until water runs through freely rather than pooling. Hold the mesh up to the light; you should see light through it evenly.
While the filter is out, wipe the sump underneath with kitchen paper — that is where fragments of glass, olive stones and rogue labels collect. Anything hard left down there gets flung around the machine all cycle. Then seat the filter properly and twist until it locks. A filter that isn't clicked back in is a classic cause of a sudden drop in cleaning quality.
