Many homes or small businesses may decide to install water softeners to address "hard water" and the resulting mineral deposits that build up from it. The Title 5 regulations prohibit water softener backwash or reject wastes from going into a septic system (conventional septic system, I/A system, or cesspool), in any amount.
However, the backwash from water softeners or from other water purification or filtration devices can be discharged into a drywell that has been properly designed and is approved by the local Board of Health. Backwash is wastewater generated from the cleaning of water and wastewater treatment filters. A drywell is a pit with open-jointed lining or holes that allow infiltration to the surrounding soil.
For more information on having a drywell designed for your home or business, you should contact your local Board of Health.