HOW TO USE DETTOL LIQUID. Antiseptic wound cleansing for cuts, grazes, bites and stings. 50ml to 1 litre, 1 capful to half pint of water. Cover with clean, dry dressing. HOUSEHOLD: Nurseries. Linen, Napkins, Handkerchiefs etc. 25ml to 1 litre, 3 capfuls to 1 half gallon of water.