My ceiling is leaking

Last night we found out that water is leaking through the ceiling of the laundry room. The shower cubicle is directly on top of the laundry room so the water is from the shower. I suspect the drain pipe that drains the shower water off has sprung a leak but the drain pipe is hidden in-between the shower cubicle and the laundry ceiling thus making it hard to get to it.

If there's any work to be done the laundry ceiling will have to be taken off meaning a costly repair. Sigh. If it's not one thing it's another. What could have caused it to leak though? Could it be the weight of the water when I collect the shower water in buckets when I shower? There's about 40 liters of water I can collect every time I take a shower, how heavy will that be? That shouldn't be too heavy to break the drain pipe now should it? I had a shower this morning but didn't see the leak, we'll just wait and see...