Do onsite/decentralized wastewater systems cause health or water quality problems?
Onsite/decentralized systems that are properly planned, designed, sited, installed, operated, and maintained can provide excellent wastewater treatment. However, systems that are sited in densities that exceed the treatment capacity of regional soils and systems that are poorly designed, installed, operated, or maintained can cause problems. The biggest documented problems involve contamination of surface waters and ground water with disease-causing pathogens and nitrates. Other problems include excessive nitrogen discharges to sensitive coastal waters and phosphorus pollution of inland surface waters, which increases algal growth and lowers dissolved oxygen levels. Contamination of important shellfish beds and swimming beaches by pathogens is also a concern in some coastal regions. EPA has developed guidelines to assist communities in establishing comprehensive management programs for onsite/decentralized wastewater systems to improve water quality and protect public health.
