septic systems don't last forever

Published on Alaska Dispatch News (

Barbara Ramsey, Clair Ramsey

May 18th, 2014


When budgeting for expensive home-related items, replacing the roof or furnace may be the first things you think about. However, many Anchorage residents need to remember another expensive home necessity to include in their rainy day fund. About 20,000 Anchorage residents depend on home sewage systems and should budget for replacing failed septic tanks. Here is what we recently learned and why you might be concerned -- whether you have one or not.


Determining the condition of a septic tank buried below ground is difficult. Even the engineer, who provides the required Certificate of On-Site Systems Approval needed for the sale of every home with a septic system, isn't able to tell unless the tank is physically exposed. Unfortunately, due to corrosion, many aging septic tanks are reaching the end of their useful lives.


System Failure

Research shows the average life span of a steel septic tank is 15 to 30 years. Tanks usually start to corrode and leak along the water line due to the presence of moisture and corrosive gases. Here are three variables that can shorten a septic tank's life span:


1. The contractor's care when installing the tank. Was installation done "like a gorilla with a backhoe"? In covering the tank, were large rocks dropped from six feet, possibly nicking the protective coating and creating weak spots for rust to take hold years earlier than anticipated?


2. Soil and groundwater conditions around the tank. Some soil conditions create an environment that can accelerate the corrosion process. Such things as high groundwater or the weight of soil can exert pressures that eventually collapse the aging structure.


3. What did the homeowner put into or on the tank? Nothing except human waste and toilet paper should go into the septic system. Unfortunately, homeowners forget that all water sources lead to the septic tank. Food particles, grease, household cleaners and other substances washed down a household drain end up in the septic tank and chemically interact -- or prevent proper bacterial interaction. Many of these slowly take a toll on the tank's interior structural integrity.


Often the only evidence of a septic tank is one or two white PVC pipes sticking out of the ground. Homeowners not aware of the presence of septic tanks can unknowingly build decks, carports or driveways on or near septic tanks. These added structures might be compromised when the corroded tank eventually collapses. They also prevent snow cover, which acts as an insulation barrier to protect the tank against frost during the winter. Without a blanket of snow for added winter protection, few tanks have adequate insulation.


The Cost

A complete, conventional four-bedroom septic system (leach field and septic tank) can cost $15,000 to $25,000, including all design fees and permits. The average leach field -- where the effluent flows and is absorbed -- lasts eight to 10 years and costs $10,000 to $15,000 to install. The leach field could need to be replaced twice as often as the septic tank. A septic tank can average $5,000 to $8,000 to install -- which does not include landscape restoration, design fees and permits. The more advanced systems -- BioCycle, AdvanTex or Aerocell -- start at $25,000. However, any of these costs can vary widely depending on site conditions.


Septic tanks come in several gauges and can have specialty coatings applied to extend the tank's life span. These upgrades can add several thousand dollars to the cost of the septic tank. Homeowners need to know about these options. They also need to consider whether they plan to sell the property before needing to replace the tank.


What to do?

As thousands of 30-year-old-plus leaking tanks release contaminants, we should all be concerned that contamination may find its way into the aquifer, which provides water to neighboring wells. Climate change may also increase the effect because less snow and rain means less water dilution into the aquifer. Anchorage has the distinction of having the highest density of on-site septic systems in the country, a fact that highlights the importance of establishing a testing protocol to identify compromised tanks before collapse and complete failure.


With each home sale, water quality and leach fields are tested. However, evaluating the structural integrity of the septic tank is currently not a requirement to obtain a COSA. Regulations should require engineers to, at a minimum, check tank integrity along the water line when any work is done to the system within a predetermined number of years after tank installation.


Homeowners need to budget for eventual septic system failure. We've seen far too many unsuspecting homeowners blindsided when they sell and find the leach field or tank has failed. The cost to repair can take a huge bite out of anticipated equity or even put the homeowner in a negative equity position.


For a better understanding of the do's and don'ts of how to maintain and maximize the life of a septic system, go to To research well and septic records go to 



Barbara and Clair Ramsey are local associate brokers specializing in residential real estate. Their column appears every month

in the Alaska Dispatch News. Their email address