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Living on Karst

A Reference Guide for Landowners in Limestone Regions

Produced by the Cave Conservancy of the Virginias, June 1997

How's Your Septic System Doing?

Do You Know?

To most of us, septic systems are " out-of-sight" and "out-of-mind." Homeowners do not often realize that proper operation and maintenance of septic systems can have a significant impact on how well the systems work and how long they last. In most communities, septic system maintenance is the sole responsibility of the homeowner.

Failing Septic Systems

When a septic system fails, inadequately treated sewage can reach the groundwater. Bacteria and viruses from human waste can cause serious diseases including dysentery, hepatitis, and typhoid fever. Many outbreaks of these and other diseases have been traced back to contaminated drinking water. Nitrate and phosphate from domestic wastewater can cause excessive algae growth in springs and streams and impair aquatic life. Nitrate is also the cause of methemoglobinemia, or blue baby syndrome, a condition that prevents the normal uptake of oxygen in the blood of young babies.

The U.S. Environmental Protection Agency and other researchers have identified failing septic systems as a major source of groundwater pollution in karst areas. Many of these failures are attributed to the presence of karst bedrock, old systems with primitive designs, and poor maintenance. The health of your septic system - and your neighbor's - is an important concern for any community seeking to protect groundwater quality, prevent expensive surface damage, and maintain property values.

Septic Systems in Karst Areas

  • Conventional septic systems should not be located near sinkholes, caves, or springs. Thin soils, sloping topography, and unstable foundations are common karstland features that affect the performance of on-site wastewater systems.

  • Regulating lot sizes and housing densities do not necessarily guarantee the protection of karst wells and springs from contamination. Ensuring that septic systems in a given watershed are functioning properly is possible with regular maintenance practiced community wide. This can be accomplished through education, incentives, or local ordinances.

Septic System Maintenance Tips

Have your tank inspected annually and pumped out every 3 to 5 years by a licensed, professional septic contractor. This is probably the single most important and least costly thing you can do to protect your system. Regular inspections and pumping prevents solids build-up in the tank from clogging distribution lines. Remember: the earlier cracks, leaks, and clogs are detected and repaired, the less potential exists for water supply and karst resource pollution.

  • Most engineers and sanitation professionals believe that commercial septic system additives are, at best, useless, and at worst, potentially harmful to a system. Under suitable conditions, septic systems naturally provide for the safe treatment and disposal of household wastewater. Avoid dumping hazardous chemicals, which would include household cleaners, down the drain. Even small amounts of paint, solvents, waste oil, pesticides and other compounds can kill the beneficial bacteria that break down wastes, and can contaminate groundwater.

  • It is important to protect your septic system from damage. Don't plant anything but grass near your septic systems. Roots from shrubs and trees can damage the tank and lines, and/or become conduits for partially treated sewage to flow downward to the water table. Prevent vehicles from parking on, or driving across, any part of the system to protect tank connections and plastic or tile distribution lines.

  • Divert other sources of water, like roof drains and street runoff, away from the septic field. Excess surface water can erode soil from around and beneath the tank and lines, resulting in subsidence and septic system failure.

Several alternative, comparably priced designs are available that improve wastewater treatment by:

  • Increasing the contact time between wastewater and soils.

  • Equalizing the dispersion of wastewater throughout the drain field (for less channeling).

  • Maximizing the natural adsorption and filtration properties of the soil.

Work with the local health department and extension service to select the best system for your site.

image of septic tank truck
image of septic tank truck