The idea of hoovers and washing machines is that they save you time. And effort.
But if you have teenagers, this is complete rubbish.
Teenagers have a touching belief that domestic appliances run themselves. Yesterday's T-shirt left in a crumpled heap on the bedroom floor, for example, will magically hook up with various dirty socks and curry-stained jeans and jog down to the kitchen.
The full load will then throw itself into the washing machine. Later, of course, the whole lot will peg itself out on the line.
Carpets get clean just by getting the hoover out of the downstairs cupboard and leaving it upstairs on the landing. Used plates, dishes and glasses become bright and sparkling just by putting them on the work surface above the dishwasher.
Microwaves, strangely, operate outside these rules. They are not expected to hum for three minutes on full power unless vital buttons are pressed.
Recently, our dishwasher broke. (In fact, in order to be extremely irritating, it just works sometimes. Run it empty, and it whooshes away with great cheerfulness. Load it up with a meal's-worth of greasy plates, and it gives you the silent treatment.) So, for the past three or four evenings, the whole family has had to wash up.
The teenagers were not impressed. On Friday night, bickering over the drying-up reached epic proportions.
'This takes me back,' said my husband, who's one of three brothers. 'This is what used to happen every night when I was growing up.'
It gives you a warm glow sometimes, returning to the dim and distant days of lighting coal fires and watching food go off in the pantry.
But I also realised something much more important. When the dishwasher worked, my teenagers did nothing. Now that it's broken, there they are in the kitchen waving tea-towels and wiping fat splodges off the cooker.
As the mum of teenagers, you get more help if domestic appliances die.
I am thinking of taking a mallet to the washing machine.