What a machine wash costs in electricity and water

Short answer: A wash at thirty degrees uses around half a kilowatt hour and fifty litres of water. Tumble drying uses two to three times as much power as the wash itself. The biggest savings lie in temperature and load size.

Temperature drives the power use

Most of the power in a wash goes into heating the water, not moving the drum. Thirty degrees uses far less than sixty, because heating power rises almost linearly with temperature. See bamboo clothing for women. Switching from sixty to thirty degrees is therefore the single change that saves the most on any one wash.

The tumble dryer is the costly part

Tumbling typically costs more power than the wash itself, because the air must be heated and kept warm for a long time to remove moisture. Air drying is free and also spares elastic and fabric. See bamboo t shirt for women. If you have room for a drying rack, that is the easiest way to cut a large share of the cost.

A full machine is cheapest per item

Nearly the same amount of water and power is used whether the machine is half full or fully loaded, so more items per wash gives a lower price per piece. See bamboo underwear for women. Do not overload the machine though, since that washes clothes worse and may force a rerun, which cancels the saving.

Fewer washes save the most

Wearing an item twice, where hygienically fine, halves both cost and wear on the fabric. See bamboo socks for women. That applies most to outerwear and trousers, which rarely need washing after one day of use, while underwear and socks should be changed daily.

Spin speed affects the bill indirectly too

A high spin speed uses a little extra power during the wash itself, but removes more moisture beforehand. That means shorter drying time, whether you tumble or hang the clothes. The small extra cost of spinning usually pays for itself in the drying that follows.

Detergent and rinses matter less

The amount of detergent and the number of rinses affect water use more than power use, since the machine heats the same base water regardless. An extra rinse uses more water, but rarely noticeably more power. The largest power cost still sits in heating the main wash, not in the rinse cycles after it.

Older machines typically use more

An older washing machine can use notably more power and water per wash than a newer model, because insulation and pump control have improved over time. Checking the energy label at your next purchase can make a clear difference on the bill over a year, especially with daily use in the household.