If during the dry season I used bath water to feed garden plants/lawn etc would it damage plants/vegetables or ruin the the soil/lawn in any way??? Is soapy bath water harmful to plant leaf’s? Wil soapy bath water make a lawn patchy? Will soapy bath water harm seedlings, young plants or do damage to gardens in general. Basically… Every chemistry you put in to ground where are the flowers will demage them, just a little bit of logic will you feel sick if you drink soapy water? YES you will, so will the flowers, and it may even kill them. .