Hi Jane, I have checked a MSDS [material safety data sheet] for Sodium Hypochlorite15%  and can see no problems with using this chemical in our 8 litre pressure sprayer, stock code U2280. You will be using the solution diluted approx. 25 – 50% I would have thought,  so no problems foreseen. Make sure that you are wearing the appropriate protective clothing as contact with eyes/bare skin nor flowers & vegetation/ grass will cause problems and make sure that pet/ child access is restricted until it has been washed off and allowed to dry. I trust that this helps?