Image by Flickr.com, courtesy of Magnus Franklin
Federal, state, and local government health agencies regulate both cesspool and septic systems. The federal Environmental Protection Agency (EPA) now prohibits cesspools that affect privately owned land and buildings. When sewage treatment plants are inaccessible, homeowners use septic systems. When limited space prevents installing a septic tank, the other option is a cesspool system. Understanding the pros and cons of both septic and cesspool systems provides valuable insight about ecological, community planning, and the environmental impact of these two waste systems.
Septic Tank System
A septic tank system consists of an inflow pipe from the house to a sewage tank, with an outflow pipe reaching an outside disposal field. Anaerobic bacteria slowly decomposes the waste. This "good bacteria" breaks down and reduces the strength of toxic organic liquid material waste by nearly 40 per cent. The sewage sludge (more dense than the liquid waste) sinks to the bottom of the tank.
Continuously filling the tank draws the lighter liquid through another pipe going from the tank into a field where the soil continues to clean the remaining liquid sewage. Eventually, clean reclaimed water seeps (leaches) back into the water table (totally water-saturated underground surface) then into the groundwater.
Cesspools use both the septic treatment tank and the outside ground absorption system. A cesspool is a simple three-foot diameter hole (a minimum width) lined with concrete blocks or stones and deep enough to reach porous soil where the earth cleans the waste. The waste flows from the house through a main pipe into the container. The solid sewage remains in the pit settling to the bottom. Soil below and on the sides of the walled containment area absorbs the liquid. Scum and floating grease quickly collects at the top of the enclosure, and a drainage trench collects any overflow.
When older septic tanks exist near streams or rivers, the danger of any unfiltered overflow contaminating these waterways poses environmental problems with toxic contamination. New septic system permits require a installation of the tank, pipes and field a minimum of 25 feet from any body of water (including flood and crop irrigation systems). Along with the personal risks of an open cesspool pit, this type of system becomes useless when overflow from the drainage ditch attached to the system seeps into wells and water supplies. In fact, the toxic liquids from the cesspool ultimately contaminate the ground anyway.
The EPA regulations banning cesspools affect only facilities serving more than twenty persons a day. Single-family homes or non-residential buildings managing sewage through this type of system fall under state and local health department rules. Most regulations affecting septic tank systems require completely pumping the tanks every two to five years, depending on the size of the container and the amount of use.
Cost and Maintenance Facts
Installing a new septic system runs between £16,250 and £19,500. The average cost to pump the tank is £162. Typically, cesspools cost half as much as septic tank installation. Too often, using a septic tank pump to drain a cesspit causes the container to collapse, spreading dangerous toxic sewage into the earth. Pragmatically, the septic tank system is more manageable, and within the guidelines for construction, safer to maintain.
- Image by Flickr.com, courtesy of Magnus Franklin