I put it in instead of the fabric conditioner. I just do one wash and it seems to do the trick for me! You are not supposed to use fabric conditioner as it affects the absorbency of the nappies, which I have found when my mum has washed then for me and used conditioner instead of vinegar. Oh, by the way, the only place I can find it is Wilkinson's, if that is any help. I tried white malt vinegar from Tesco's first and it didn't work, I just ended up with strange smelling nappies.