The outside drain that my kitchen sink, dishwasher and washing machine empties into is well and truly blocked, so..
It connects to my pressure washer, and is doing a good job so far..
Quite a decent sized fat-berg removed so far (the rest of stuff in the pic is also fat), but unfortunately it's still blocked despite all 15 M of hose going down the drain, so I may have to attack it from the septic tank end instead.
There was a piece of glass in the drain which nearly took the end of my finger off, so I'll have to resume fat busting duties tomorrow.
Fwiw I try not to put fat/oil down the drain, so I'm guessing that's a culmination of many many years of the previous owners doing exactly that.