I have taken to not bringing the detergent, and instead I buy a small bottle of it at the grocery store. I used to bring the tablets, but they are hard to find now. I can't bring powder, because DH gets itchy from powder.
My neighbor has been known to squirt a small squirt of dish soap into her washer if she runs out of laundry soap..be careful though, because dish soap bubbles a lot more than laundry soap.