Why does my washing machine drain water during the wash cycle? It will fill up to specific level and then start to drain during the wash cycle. When it gets too low, it starts to fill again and so on.
The drain hose is probably too low. The end of it has to be higher than the top of the wash drum (not the entire machine just the drum).
i.e. For a front loader this is the top of the drum, for a top loader this is the high water mark.