Water from the sink is flooding the toilet

[yamyam999]

I have a shower room with toilet and wash basin on the side of my house.
We don't use the shower so for some years we have utilised the space as washer / dryer room. Now when I run the tap in my wash basin or the water from my washing machine goes into the sink the water gushes into the toilet and floods.
Can anyone give me advice on what's causing this and is there a simple solution to the problem ?

 

[jobloggs]

You must have a blockage in the soil/sewer pipe downstream of where the waste from the basin connects in to the 110mm pipe from the toilet. Flooding occurs because basin is at a higher level than the toilet rim.

Is there an inspection chamber/manhole outside? If so lift cover. If Dry the blockage will be back towards the soil pipe to the toilet. You might be able to clear it by pushing a garden hose back up the pipe with a spray nozzle set to most forceful jet. If not you need a set of sewer rods or call in the experts.

 

[yamyam999]

Thank you for the advice.
I'll get my hubby to have have a look when he gets in from work