When turning a newly installed septic system over to the owners, you can feel a bit like a doctor sending parents home with a newborn. You can give them advice on how to keep it healthy and hope for their sake that they heed it.

One key piece of advice you can give in this often germ-o-phobic world is to be careful with cleaning products, especially antibacterial formulations. If you're also in the system maintenance business, you can watch your customers' systems for symptoms of problems caused by these cleaners and other chemicals people sometimes flush.

Signs and symptoms

Have you ever opened a septic tank and found that it looked or smelled "off"? Has a customer's effluent screen been plugging up routinely? Have you seen a newer drainfield, properly installed, get clogged?

These issues might result from a high input of cleaners, chemicals and medicines. In the septic tank, you may discover a chemical odor, high or low pH, and lack of tank stratification. This is because chemicals have killed off or depleted the bacteria on which treatment depends.

Anaerobic bacteria in the septic tank produce the signature "septic" smell by breaking down organic material and releasing gases such as methane, hydrogen sulfide, carbon dioxide and ammonia. Then aerobic bacteria in the soil treatment system destroy disease-causing pathogens. These bacteria need life-sustaining temperatures, a steady supply of food, neutral pH, and freedom from exposure to toxic chemicals.

Getting a diagnosis

The best way to start troubleshooting a septic tank is to obtain a profile using a sludge and scum measuring device. You should see three distinct layers: sludge, a clear/gray zone and scum. A lack of a scum or sludge layer may indicate emulsification caused by chemical usage.

Emulsion is the mixing of liquids and solids that are normally separated. A tank that is emulsified will cause plugging of the effluent screen in a very short time.

Next, you want to check the temperature and pH. The temperature should be above 39 degrees F for BOD removal and 50 degrees F for nitrification. The bacteria need a neutral pH. A simple pH probe will tell you if the sewage is:

Neutral (pH 6.5 – 8)

Acidic (pH below 6.5)

Basic/alkaline (pH above 8)

An acidic value could indicate chemical overuse in the home. That points to possible culprits such as coffee, soda, acid-based cleaners or nitrification. If the reading is basic, ammonia-based cleaners or lye may be the cause.

Other issues that affect tank performance are variable flow patterns and lack of maintenance. If the tank is working properly it will take out approximately 50 percent of the BOD5 and TSS. If not, BOD and TSS will likely overload the advanced treatment unit or soil treatment system downstream, possibly causing an excessive buildup of the biomat that can eventually lead to surfacing of effluent.

Looking deeper

The next step is a homeowner survey to determine what is going down the drain. You are looking for cleaners, sanitizers, disinfectants and antibacterial agents – anything that might kill the bugs. When looking at products in the homeowner's cabinets, there are three label indications you might see:

DANGER means the chemical will kill the bacteria and should be used very seldom or, better still, eliminated.

WARNING means the product should have minimal impact on the system but should be used sparingly.

CAUTION typically means the product will have little effect and can be used in normal amounts.

The use of biocides, including antibacterial or disinfectant products in the home, can and does destroy good and bad bacteria in the treatment system. Using normal use amounts of these products will destroy some beneficial bacteria, but the population will remain sufficient and will recover quickly enough so that significant treatment problems do not occur.

On the other hand, excessive use of these products can cause significant and even total destruction of the bacterial population. More research is needed to determine what amounts are "excessive" and which products are more or less harmful to systems.

Total impact

Typically, the use of a single product or single application will not cause major problems, but the cumulative effect of many products throughout the home may do damage. For example, high concentrations of chemicals can kill or retard the growth of the bacteria in the septic tank, advanced treatment unit and drainfield. If the bacteria are destroyed, solids accumulate in the tank much faster and can create problems in the soil treatment area.

Pharmaceuticals also come into play. The human body does not completely metabolize medications, so they enter the septic system through body wastes. Certain medications may cause premature septic system failure. What are these products we are talking about? They include:

Steps you can take

If you find a system has been harmed by chemical inputs, there are a number of steps you can take as a professional advisor and service provider. If the problem was likely caused by a one-time shock load, you can simply monitor the septic tank and see if it comes back, or clean out the tank and start over if the issue persists. If the issue is more long-term, there are a number of things you can recommend or do to protect the septic system:

Educate the system users about how their use of chemicals is potentially impacting the system. Advise them not to flush leftover medications. Some pharmacies will dispose of unused medications, and many communities have "take-back" programs.

Advise the occupants to minimize the use of antibacterial soap, disinfectant cleaners and bleach.

Eliminate all nonsewage sources of water into the system, including water treatment device backwash water, groundwater and surface water. Advise the occupants to space out water usage to provide more consistent flow and longer detention time.

Monitor the system's sludge and scum levels.

For commercial systems, consider isolating toxic waste streams, such as from janitorial sinks and drains, into a holding tank.

Increased system maintenance may be required, particularly with certain strong medications, such as chemotherapy drugs. The tank may have to be pumped more often to remove solids that accumulate
rapidly due to loss of beneficial bacteria.

Take samples of COD, BOD5 and TSS. Compare the COD values versus the BOD5. If COD is significantly higher than BOD5 (more than double) this may indicate a high chemical oxidation of cleaners, medicines and chemicals. You may also consider having the laboratory run BOD5 at various dilutions. If high levels of biocides are present, there will be no BOD5 demand at lower dilutions, but at higher dilutions where biocide concentrations are lower, a BOD5 demand will exist.

If the septic tank gets too toxic, it may be necessary to use the tank as a holding tank during a prescribed treatment.

Fill the septic tank with clean water after pumping to dilute the concentrations of the medicines at the restart of the system.

If the system has no effluent screen, add one. The screen will need to be cleaned frequently if the septic tank is upset. An alarm is a critical part of an effluent filter installation, as it will indicate when the filter needs to be cleaned.

Consider installing additional septic tanks or a pretreatment device as possible design changes that could further help settle out or break down some of the constituents.

Use an additive?

All of these practices work toward preventing the loss of beneficial bacteria throughout the septic system. Whether commercial additives help is a matter of debate. Further research is needed on the effectiveness of additives (bacterial starters and feeders, enzymes, cleaners). However, no additive is a substitute for proper system care and maintenance.

Knowing the potential impacts of household products and medicines can help you get new septic system owners off to a good start, and help owners of existing systems improve performance and extend service life.