no rain barrel , but sounds like you all would like to save on watering plants. when we lived in the desert we bought some blue tubing from lowes and clamped it on the hose that is on the washer. then ran it out to the grass and bushes, etc
and let the laundry water water it all. we just moved the hose wherever we wanted it to water. at that time it was 100 or more just to water the yard so that helped alot. if you have a septic tank it doesn't have to get so filled up just doing laundry too.