What an overfilled machine does to the cleaning
Short answer: Water and detergent cannot reach everywhere, and the clothes cannot fall freely. The result is that some things get clean and some only get wet.
Movement is the wash itself
Cleaning comes from clothes being lifted and dropped back into the water again and again. That movement pushes water and detergent through the fabric and loosens dirt. Without room in the drum it does not happen, and the clothes are pressed into a dense lump where only the outside gets a proper wash.
Detergent spreads unevenly
Without movement the detergent does not reach every layer. Some pieces get too much and others almost none, which can leave residue on the fabric. In a tightly packed load the detergent stays where it was poured. See bamboo sleepwear for men for clothes that are washed often.
Rinsing suffers too
There is not enough water to rinse residue out of a tightly packed load. Soap and dirt stay in the fibres, and the clothes can feel stiff or smell of detergent afterwards. Add a rinse after a full machine, but it is better to leave room from the start. See bamboo bedding and bamboo fitted sheets.
How to judge a full machine
A good rule of thumb is a hand's width between the clothes and the top of the drum. If you cannot fit your hand in, there is too much. The clothes must be able to fall freely as the drum turns. A door glass filled to the top means the load is too big for a proper wash.
Sheets and large items are worst
Large items such as sheets and duvet covers wrap around the rest of the laundry and shut everything in. Water and detergent cannot get in, and the clothes inside the lump barely get wet. Wash large flat items on their own, or with only a few other things, so they can move freely.
What a heavy load does to the machine
A tightly packed load is heavy, especially when wet, and it puts extra strain on the machine. During the spin the machine can also go out of balance, so it is noisy and shakes. That is bad for the wash and for the machine. Load a little less and run an extra wash when needed.
A fuller machine does not always save anything
If the clothes have not come clean, they must be washed again, and then you have saved neither water, power nor time. One good load that comes clean the first time beats two half loads that must go round again. Fill so the clothes can move, rather than stuffing the machine.
Mixed laundry in a full load
With clothes of many sizes and thicknesses, a full load is even harder to get clean. Small pieces vanish between the large ones, and thin ones are dragged around by the heavy ones. Sort by thickness if you can, and give thin garments a load of their own so they get the wash they need.
Frequently asked questions
How much can go in?
The clothes must be able to fall freely. A hand's width to the top of the drum is a good rule of thumb. If your hand will not fit in, the machine is too full.
Is it worse with sheets?
Yes. Large flat items can wrap around the rest of the laundry and shut everything in, so the water cannot reach it. Wash them on their own or with only a few other things.
Do I save water by filling up?
Only if the clothes actually come clean. Otherwise they must be washed again, and then you have used more water and power than if you had split the load from the start.
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