What are RI Towns Doing?
Block Island
South Kingstown

The BIGHP Project

RIWIS (Rhode Island Wastewater Information System)

Onsite Systems Basics
Onsite treatment systems
Property owner's guide

Wastewater Manager's Toolkit
Creating a management plan
Drafting an ordinance
Developing treatment standards
Funding and staffing a program
Getting the message out
Tracking inspections
Achieving results

Onsite System Research and Assessment
Demonstration systems
Soil suitability
Using GIS for evaluation
Water quality monitoring

Training and technical support

This website is under construction.

Please check back soon for more complete information!

Understanding Onsite Systems

This website offers information regarding the function of onsite wastewater treatment (septic) systems. A list of the information available is below.

Conventional Treatment Systems   Advanced Treatment Systems
- Primary Treatment - the septic tank - Primary Treatment
- Distribution Box - Advanced Treatment Technologies
- Drainfield Options   ~ Aerobic Treatment Units


~ Trench Drainfields   ~ Media Filters


~ Leaching Chambers

  ~ Sequencing Batch Reactors


~ Eljen In-Drains

- Final Dispersal / Drainfield Technologies
  ~ Mound and Fill Systems

- Pumps, Timers, & Controls:

    moving wastewater through the system
  -Demonstration Systems

When properly sited, designed, installed, and maintained, onsite wastewater treatment systems are often the best choice for wastewater treatment in many areas, from public health, environmental, and economic standpoints. Onsite wastewater treatment allows water used in homes and businesses to be treated and recycled to replenish local groundwater supplies. This benefit of onsite treatment is not realized with municipal wastewater treatment, which discharges partially treated wastewater directly to rivers and coastal waters, sending wastewater either further downstream or out of the watershed entirely, and returning none to the landscape to replenish groundwater aquifers. This loss of groundwater recharge reduces the amount of groundwater available for drinking water wells. In coastal areas, depletion of ground water resources can lead to salt-water intrusion and loss of potable freshwater supplies. Because groundwater is the main source of flow to streams during dry weather, loss of recharge can also lower streamflow to levels that can no longer support healthy aquatic life.

The two main classes, or groups, of onsite wastewater treatment systems are explained in the following sections, and are termed conventional treatment systems and advanced treatment, or innovative and alternative systems.

The conventional and advanced treatment system designs described and explained below are those currently approved for use in Rhode Island (as of November 2006). Many of these designs are used elsewhere in North America. Information and regulations about onsite wastewater system design for New England states can be found at the following sites:

State Regulatory Agency
Regulatory Program
Dept. of Health & Human Services
(Division of Environmental Health)
New Hampshire
Rhode Island


Copyright 2006 URI Water Quality Program