Help! DP poured milk down the outside drain...

[GrimbleGrog]

...and now it stinks to high heaven.

I poured a bit of zoflora down it to no effect, any ideas?

Bleach and got water might do the trick

hot water with washing-up liquid to loosen the fatty deposits. A watering-can is better than a bucket as it will run down the sides more.

Is it a rainwater drain?

Bicarb of soda and vinegar - it fizzes which agitates all the gunk stuck to the sides of the tube!

Ammonia, or anything with ammonia in it.

Buckets of hot water and fairy will do it-go easy on the fairy.

Jeyes fluid followed by lots of water. Of course that will smell.worse than the milk.......