SEPTIC GUIDES FOR HOMEOWNERS
What does a UV bulb do in a septic system?
A UV lamp is a disinfection step on some aerobic septic systems. After wastewater goes through the treatment unit, the treated liquid, called effluent, passes through a separate UV chamber. Ultraviolet light inactivates many microorganisms by damaging their genetic material so they cannot reproduce. The UV step depends on the upstream system to remove solids and treat the wastewater first.
What needs maintenance?
- Replace the lamp on its model’s schedule. A lamp can still emit visible light after its germicidal output has declined. Record the installation date and follow the manufacturer’s rated service interval.
- Have the quartz sleeve inspected and cleaned as directed. The sleeve keeps wastewater away from the lamp while letting UV through. Film, scale, or solids on the sleeve can block light from reaching the effluent.
- Check the control and alarm. A technician can verify the status indicator and alarm and check the power supply, lamp connections, and ballast if there is a fault.
- Maintain the equipment upstream. Cloudy effluent or suspended solids can shield microorganisms from UV. If the chamber keeps fouling, ask whether the treatment unit or filters need attention.
What happens if the lamp fails?
Effluent can still pass through the chamber even when the lamp is off or weak. Unless the installation has a separate shutoff or diversion feature, drains may seem normal while disinfection is reduced or has stopped. A failed lamp is one possible cause. Loss of power, a ballast or connection fault, and a dirty sleeve can also prevent effective disinfection.
What warning signs should I look for?
- A UV, lamp, or disinfection warning on the panel, or a buzzer linked to the UV unit.
- A normal status light that goes out or changes. On the Norweco AT 1500, the green indicator goes out when its monitoring circuit signals a lamp fault. Indicators differ by model.
- A lamp that is overdue for replacement, or repeated alarms after service. Some systems monitor lamp operation without measuring how much UV reaches the effluent.
If a warning appears, note what the panel says and contact your septic service provider. Keep the chamber closed. Looking directly at an operating UV lamp can injure your eyes and skin. Read the UV alarm guide.
Norweco AT 1500 installation and operation manual · Norweco AT 1500 control and alarm information