Outside drain blocked

[namegoeshere]

The water from the kitchen empties into the drain in the garden- which is connected to the sewer. The drain keeps blocking though. It's not mud or pebbles - I'm pretty sure it's kitchen stuff.
I've tried using a plunger, and the long metal rope thingy - but they have no affect as far as I can see. The drain seems to have some plastic bend or such in it?
Lifting the manhole cover it's fine under there, so the prob has to be

I would rather use some tool to fix it rather than pour bleach or other chemical products down there - as its seems unblocking it will be a regular chore.

Thanks for help

 

[noseall]

have you , or do you need to clean out the gulley trap?

 

[namegoeshere]

I haven't done that - I think... What is the Gulley trap? Is it the plastic thing around the bend in the drain?

 

[JohnD]

stop putting fat and kitchen waste down the plughole.

 

[robertito]

We have this problem from time to time, even though we try hard to avoid any fat or waste going down the sink. The problem is that there are always traces of fat.
You'll probably have to use chemicals, or buy/rent a backward facing jet thingy.