Its not uncommon, esp if you don't use much wash additive, for the filter in the washer pump to get clogged.
Never mind, its easy to clean.
If the car is warm, be aware that cooling fans may start! Disconnect battery first!
For prefacelift:
Open bonnett.
Undo 2 torx screws that hold grill on, and unclip grill.
Reach down behind where air intake starts, there are two pumps. Right hand one is larger and is headlamp washer (if fitted). Left hand one is the windscreen one.
Tilt top of windscreen pump towards back of car to unclip, then lift up and withdraw.
Where the pump has come out from, there is a rubber grommet - remove this. (Its likely at this point that the washer bottle will empty through this hole).
This grommet has a built in filter - clean this out under a tap, ensuring it is completely clear.
Refit is the opposite, ensure that grommet and pump are properly seated to stop leaking.
Facelift should be similar, but without needing to remove grill.