My thoughts on doing laundry

Well this is my first post and I have to say I am not sure what I am getting into.  But I think it is kind of neat to "talk" to others about what we have learned in saving this world.  I have been hanging my clothes on a laundry rack for years.  Started washing most of my clothes in cold water and now reading about how the sun disinfects will start doing my sheets in cold water also.  But I have a question.  I tried to use the gray water from laundry to water the grass and it killed the grass and I was using an eco-friendly soap supposedly.  What does one do?  And can anyone tell me why my grass died?