Septic Systems & Water Treatment Discharge

Household Water Treatment Systems Discharge


Many household water treatment systems regularly discharge backwash water as part of their cycle. In theory, all wastewater discharges within the state are only allowed by permit, as authorized by the Department of Environmental Protection (DEP). For example, the DEP has delegated authority to issue permits for household septic systems to local health departments with oversight by the Connecticut Department of Public Health. The Public Health Code specifically prohibits water treatment discharge into septic systems; however the DEP has never approved a permit process for this water to go elsewhere so the entire process is in a legal black hole. Since installations of water treatment systems require no permits or inspections it has long been common practice to run the discharge line into the septic system.

The basic rationale was threefold:
  • The discharge probably did little damage to the septic system (some of these systems have been discharging into septic systems for many years with no apparent damage to the system)
  • There was no approved way to discharge the water (where else could it go?)
  • Who would ever know?
Recently, each of these 3 rationales have been challenged:
  • There is some evidence that the discharge may slow the biological activity in septic systems and shorten their life,
  • The Connecticut Department of Public Health has adopted DEP draft guidelines for discharge of water treatment system wastewater to a system separate from household septic systems as an accepted (if not permitted) practice,
  • Home inspections at time of sale now frequently note the non-permitted discharge.
So within the real estate market what are buyers, sellers and agents to do when an inspection notes a discharge into a septic system?

Discharge Recommendations

The Madison Health Department recommends that water treatment system discharges be removed from septic systems and directed to small leaching systems using the recently adopted Department of Public Health guidelines. Our current procedure is to issue an “no charge” permit for these installations. After the installation is complete a new “As Built” form is provided submitted providing the location and details of the separate leaching system. Please note that home inspection reports are not submitted to municipalities and there is no process to mandate removal of non-permitted discharges, so at the most basic level the issue is between buyers, sellers and their agents just as it was before home inspections were a normal part of home sales.  

Additional Information


Connecticut Department of Public Health: Private Drinking Water in Connecticut 

close carousel
close carousel