What Is a Discharging Septic System? (VAG40 Permit)

A Septic System With No Drainfield

Most septic systems send treated water into the soil through a drainfield. A discharging system doesn’t. It treats the wastewater much harder, disinfects it, and releases it above ground to a stream, a ditch or a drainage way. Virginia allows them for single-family homes only where the lot can’t support a drainfield: the soil is too shallow, too wet or too tight, and there’s no other way to serve the house.

A typical unit has a septic tank, an aerobic treatment unit that uses air and bacteria to clean the water, a disinfection step (a chlorine tablet feeder or an ultraviolet light), and an outlet pipe. Because the water leaves the property, two agencies are involved: the Virginia Department of Health (VDH) permits and oversees the system under 12VAC5-640, and the Department of Environmental Quality (DEQ) covers the discharge itself under the VAG40 general permit.

The VAG40 General Permit

VAG40 is DEQ’s Virginia Pollutant Discharge Elimination System (VPDES) general permit for domestic sewage discharges of 1,000 gallons a day or less, found at 9VAC25-110-80. Rather than writing a separate permit for every home, DEQ writes one general permit and each home gets a coverage number under it. That number starts with VAG40 and is printed on the coverage letter; it’s the number TankVault keeps with the system.

The permit is reissued every five years. The current one took effect on August 1, 2026 and runs to July 31, 2031. Owners have to renew their coverage when the permit is reissued, so that date matters even if nothing about the system has changed.

The permit sets limits on what leaves the pipe: BOD₅ and suspended solids (30 mg/L each in most streams), chlorine residual or E. coli depending on how the system disinfects, pH, and dissolved oxygen. Streams with very little flow, and the Potomac River embayments, get tighter limits. For a single-family home the permit leaves day-to-day operation to VDH’s regulations, which is where the operator requirements come from.

Operator Visits Every Six Months, One Sample a Year

Under 12VAC5-640-500 the owner must “engage a licensed operator,” and the operator must visit at least every six months. That’s twice as often as a normal alternative system, because a discharging system that stops working sends untreated sewage into a stream rather than into the ground. The operator holds a Class IV or higher wastewater works license, or an alternative onsite sewage system operator license.

At each visit the operator:

• checks the whole system against the approved O&M manual: tank, aeration, disinfection, outlet;
• runs the field tests and takes any sample that’s due, without forcing a discharge to get it;
• tells the owner within 24 hours, in writing or electronically, if maintenance or a repair is needed;
• keeps a log of the visit, the results, repairs and recommendations, and gives the owner a copy.

Sampling follows 12VAC5-640-490 and the VAG40 permit. A new system gets its first formal sample 45 to 90 days after it starts discharging. After that, the permit calls for a grab sample once a year in most streams, and quarterly for Potomac embayment discharges. Results for a single-family home go to VDH electronically by the 15th of the month after the sample (12VAC5-640-510), the same portal and deadline as other AOSS reports. See Virginia AOSS inspection requirements.

What the Owner Has to Do

• Keep a licensed operator on the system at all times. Filing the required reports counts as evidence that the contract is in place.
• Make sure the operator visits at least twice a year and takes the samples.
• Keep the treatment works maintained and repaired promptly. Chlorine tablets run out; UV bulbs burn out.
• If told a repair is needed and the discharge isn’t meeting its limits, start pump and haul and follow the local health department’s directions until the system is back to normal.
• Keep the operator’s log and the O&M manual at the property, show them to the health department on request, and pass them to the next owner.
• Follow the VAG40 permit conditions, including renewing coverage when DEQ reissues the permit.

Missing samples has a cost. If an owner misses three or more required samples in any five-year period, VDH voids any monitoring waiver and requires an operation and maintenance contract that includes monitoring.

How TankVault Keeps Track of This

TankVault schedules discharging systems on their own clock: an operator visit every six months, a sample every year, and the VDH report due the 15th of the next month, with the first sample 90 days after start-up. It keeps the VAG40 coverage number with the system and reminds the operator ahead of the permit renewal. Lab results are read for the operator and checked against the limits, and the homeowner letter is drafted for the operator to approve. See what it does for septic companies and for homeowners.

Related reading: how often to pump a septic tank in Virginia (the county pump-out applies to discharging systems too) and North Carolina operator inspections.

Questions and Answers

More Guides

• Virginia AOSS Inspection Requirements, Explained
• How Often Do You Pump a Septic Tank in Virginia?
• North Carolina Septic Operator Inspections (15A NCAC 18E)

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