Washing Machine Waste Water Flowing Up Sink

[DIY_Novice]

trying to install a washing machine. ran a t piece off the cold and into washing machine inlet. waste pipe from washine machine is connected into sink trap.

everything seemed fine, no leaking joints, however, when the washing machine drains, the water is filling back up through the sink. this also causes some leakage - it seems that the sink waste pipe doesn't like all this water flowing back up it.

anyone any suggestions as to what could be causing the water not to drain away correctly?

 

[breezer]

pipe blocked, flowing up hill.

rip it out and pit in a stand pipe that goes directly to waste

 

[DIY_Novice]

pipe blocked, flowing up hill.

rip it out and pit in a stand pipe that goes directly to waste

thought it may have been a blockage. water seems to drain away ok from sink but i suppose when the deluge arrives from washing machine it's enough to back it right up.