Can I use any detergent in a Handi-Wash

Yes: but be sure to only use the smallest amount, that’s all that is needed, when travelling you may decide to use a liquid laundry detergent, Washwell (available in a tube, creates suds even in hard water).  When choosing a powder detergent always look for NP on the packaging, Non Phosphorous detergent doesn’t damage our fragile eco-system, we recommend Bio-Zet.