Using too much laundry detergent

The most common laundry mistake is also the most counter-intuitive: overdosing the detergent. Extra suds feel like extra cleaning, but modern machines — especially high-efficiency drums — cannot rinse a double dose out. The leftover sits in the fabric and in the machine.

Why it backfires

Excess detergent leaves a residue that makes towels stiff, dark clothes dull and skin itchier than the fabric softener advert claims. Inside the machine, the residue feeds the mould and smell that people then attack with yet more product — the gasket-and-filter cleaning guide exists largely because of this cycle. Suds can also cushion the drum's load, reducing the mechanical action that actually does the cleaning.

The fix

Measure. The cap's lines are for a standard load in hard water, and most people wash softer water with lightly soiled clothes — one-third to one-half of the recommended dose is usually plenty. If the drawer or clothes feel slimy after a wash, run a hot empty cycle and halve the dose going forward. Powder in soft areas, liquid in hard: pick by your water, not the advert.

Keep it from happening

Ignore the "fill to top" instinct permanently, dose by soil level (gym kit versus an evening shirt), and if your machine has an extra-rinse option, spend it on towels and bedding rather than more soap. The drainage guide and the seasonal checklist cover the rest of the machine's keep-it-honest routine.