There are plenty of reasons for your washing machine to leak water, here are a few:

1) Soap drawers and the soap dispenser to tub hose become clogged.
2) Detergent dispenser lids become clogged and distorted and incoming water overflows the soap compartment.
3) Various hoses split or get punctured by such items as pins, nails, bra wires, screws etc...
4) Door seals get ripped or torn by zips from jackets or overloading the washing machine with clothing
5) Not forgetting wear and tear as rubber perishes door seals and hoses can and do just wear away.

On top of those there are also electro mechanical reasons for washing machines leaking:

1) Programme fault
2) Not draining at the correct time
3) Over filling with water
4) Pressure system fault

Usually, unless it's an external leak, such as one of the incoming water pipes from your supply to the washing machine that's leaking, we recommend you call a service engineer. If you have a washing machine that leaks, turn it off and have it repaired.