Not sure what sort of item you are thinking of, but we have to sterilise bladders and tubes for drinking on the move eg Camelback, and find baby bottle sterilising tablets much easier than liquids. Our technique is to rinse thoroughly, as soon as possible after finishing use, to remove residues of sports powders (sugars and salts), then make up a solution of tablets in water and pour into bladder & tube. We find tablets, individually wrapped in foil, much easier to carry and use "in the wilds" than liquids which can leak etc. Bladders have volume measures, so getting the right concentration is easy.
Tablets definitely as good as liquids, better in fact, but neither will sterilise if residue is left on item to be sterilised.