It is a common fault that the drain fails to work in most machines in a period of time and is the most problematic fault in a washing machine. In all occasions it is important that your observation is most important and so is vital to the identification /rectification and solution. If you have noticed that water has leaked then as the drain hose pump/valve and fittings are located on the underside of the machine it is important that you look for possible leaks here. In some cases the drain hose would be clogged at the drain end to outlet of the house and so there will be back flushing resulting in overflow to the outside. Also the drain pump/valve can be clogged. Now remove the drain hose clamps and remove the drain pump/valve, clean the drain pump/valve, use back flushing to clear off all dirt. Now test using power to see if this works and can be simulated. When refitting, the hose must be tightened properly. If the pump/valve does not work even with power then it must be replaced. If there is intermittent power to the drain valve/pump then the program controller unit is a suspect.

Finally the washer must be placed with a tilt- use a spirit level- so that all water will drain to the outlet port and thereby there is no residual water remaining.

Replacing the pump on a Bosch machine, please check this link for tips:

http://www.espares.co.uk/advice/washing-machines/a/7/1373/how-to-replace-the-pump-on-a-washing-machine-.html