I just bought a TN Discovery bivi bag, spent a night on the hills and it got a bit dirty. The label says to wash as synthetics, but I don't think I should be using regular washing powder. Any suggestions as to the best way to clean it (I don't mind hand washing!) Cheers

i don't clean mine!
I leave it to dry and gently brush off the dirt.
never really thought about cleaning it

Dror,

I'm with wayne on the cleaning front, ie i dont do it, just allow to dry and brush it off.

The only time i deliberatly put water on my bivi bag is once a year to reproof it(usually spring time infact i'm going to do it now....thats just reminded me) with a wash in type such as grangers at that point it gets a wash in a "tech wash" before the reproofing treatment.