Thank you all for your responses. The septic tank at the house was only designed for 3 people and we have 4 living there. The county gave us a conditional permit for the 4th person. This is why I don't want my mother-in-law to be a regular user of the facilities in the house. However someone did suggest getting the septic tank drained more often if the black water or grey water are drained into it, or if she uses the house facilities. That might work, but I'm not sure if the septic system can handle that much that fast. Also, I've read some other forums about being able to dispose of grey water in other ways such as watering plants, etc. Is that a possibility or a big no?
Thanks again
