Thursday, June 25, 2009


I hope that Leslie and "Hey Culligan Man..." will forgive any transgressions they may perceive form this missive.

The introduction of sodium chloride (hereafter called salt), in the form of brine from water softener backwash into septic tanks is very questionable at best. There have been claims that excessive levels of salt in effluent will stratify in certain types of drain field soils, and will clog soil pores kinda like biomat, increasing the potential for early failure of drain fields. Reducing the ability of a septic tank to sequester bio-solids in our waste will certainly help shorten the functional life of a drain field. Bacteria are responsible for this sequestration process. Bacteria are responsible for separating settlable and floatable solids, allowing these solids to be retained in the septic tank. Salt and bacteria aren't exactly a good mix.

Septic systems do not function properly if there is a reduction or the outright destruction of bacteria in the septic tank. Salt is a food preservative. It kills bacteria that would otherwise "eat" your food (another way to say this is it keeps food from "spoiling"). You wouldn't want to spoil your septic tank would you? So back washing water softener brine into your septic tank is putting in liquid that has the potential to reduce or outright kill the bacteria in your septic tank. Doesn't make sense that you are often forced to do this by your local officials does it?

Government officialdom often forbids the removal of the backwash from your water softener from your septic tank. They also insist that you do nothing to inhibit the proper function of your septic system. This has always been a head scratcher for me.

The backwash brine from water softeners is loaded with salt (guess that's why its often referred to as brine). The concentrations of salt in the back wash will not only stress the bacteria in the septic tank but the salt will leave the septic tank in the effluent and (possibly) stratify in the soils around the leach lines reducing or even stopping the movement of liquid through the stratified layer. As drain field failure is designed into and expected for conventional, anaerobic septic systems within a couple of decades of the installation, excessive amounts of any material capable of clogging drain field soils potentially decreases the time period to failure. Enter salt, stage left....

There are several products on the market that claim to reduce or mobilize stratified salt that could be clogging soils around drain fields. I personally have never used these products but I have heard of claims of drain fields being very temporarily restored to proper function after application; though there was no proof that the drain field problems were related to salt blockage. The chemicals could perform some other function to temporarily create pourosity in the soil. Most likely these problem sites were a combination of Biomat clogging along with other clogging materials, with salt possibly being one of the materials.

What to do? Well, there are only a couple of choices that are reasonable. If you don't want to remove the backwash from your septic system, switch from sodium chloride to potassium chloride. You shouldn't find a significant difference in water quality. This may not be a perfect answer but it certainly will help. Another, and the most tried and true method for a solution, is REMOVE the backwash from the septic tank and send it somewhere else where it can't cause problems with the proper function and potential life of your septic system!

You should remove the discharge line for the water softener backwash from your septic tank and have it discharge to another place and leave the septic system to handle your biological waste from the home. Installing a small drain field to handle the water softener backwash is easy and relatively inexpensive. After all, the salt is still going into the soil so what's the difference between your septic drain field and a backwash drain field? Interesting designs are available. Let me know of your interest.

Anaerobic conventional septic systems have been historically treated as a dumping place for any type of waste liquid. This is fast becoming a problem for the industry as new standards are being adopted. With the increase for, or outright requirement of, aerobic treatment for septic systems, backwashing water softener brine into septic tanks should be prohibited when aerobic treatment is used. This is still hit and miss with officials.

Basically putting anything into a septic tank that you wouldn't first put into your mouth, or anything that is fundamentally toxic to bacteria, should not be put into septic tanks. Since we have not paid attention to what goes into a conventional septic system until recently, it is difficult to change people’s thinking and behaviors. Fortunately, reasonable amounts of the normal products we use in our homes can go into a septic tank with the rare occurrence of catastrophic consequences. The foundation problem for septic system failure still remains Biomat clogging of infiltrative soils around disposal fields.

Thanks for stopping by.

Thursday, June 11, 2009


Here's my latest nugget of new information about septic drain fields. Before I start, I can only encourage people to become informed and educated about septic issues as the future surely holds more potential for being "laid over a barrel" by the generic industry and officialdom.

I realized years ago that there is very little thought or consideration given to the eventual physical degradation occurring to a typical drain field or leach line. The issues are occasionally acknowledged and heads nodded about them, but no one ever seems to look into the what they are nodding about. There is biological degradation or biomat clogging of drain field soils that is inherent in conventional, anaerobic septic effluent that is discharged to a drain field and everyone should understand that issue. There are other physical issues that also reduce some of the potential of a drain field. They are few, but need to be described. Because we introduced the general idea of remediation for drain fields over ten years ago, we have made a serious study of what problems could reduce our success in remediation. We found that there really aren't that many physical issues that can or do occur. I will attempt to describe the most common of these physical issues: siltation.

Over time, silt in the soil will be percolated into the spaces between the drain rock from years of rain and or snow melt; that is if you don't live in Arizona and the Southwest. I was told when I started in construction that siltation spelled the end of a drain field. Well it doesn't. Here's why. An engineering study was done by an engineering group (surprise that an engineering group does engineering studies) here in Northern California. They discovered, with round or spheriod shaped stone, or man made stone replacement, that when you take a cubic foot of space and fill it with any round or spheriod shaped material of any diameter, the material took up approximately 65% or the volume of the cubic foot of space. That left 35% for air space. That includes all diameters from bowling balls to marbles to sand to silt. What was critical was that there be no flat surfaces that can "marry" together eliminating the air space (i.e. crushed aggregate doesn't apply to this study).

This translates to a potential liquid storage volume per cubic foot of drain field as follows: 7.48 gallons per cubic foot minus 65% or 4.86 gallons which equals 2.62 gallons of space for liquid storage per cubic foot of drain field. If one had, say, a 100 foot leach line, with a width of one foot and one foot high of aggregate (natural or a man made synthetic replacement) you would have a total liquid storage capacity of 262 gallons. **This example is for descriptive purposes only and is not meant to indicate anyone's particular drain field.** When siltation occurs, 65% of the air space is filled with spheriod shaped silt particles. There are two issues of importance when siltation occurs.

The first issue to understand is the silt does not become compacted as would be expected in normal soil conditions. Compaction does not occur because the aggregate carries the compressive load to ground around the air spaces now filled with silt. Therefore, there is no pressure on the silt to cause compaction. The silt remains light, airy and permeable to the passage of liquid through it. Being permeable means there is capacity for leaching liquid through the uncompacted silt (liquid that is not filled with biomat producing bacteria).

The second issue is there is still air space between the silt particles. Remember the example above? I'm trying to remember. The silt is spheriod in shape. It therefore takes up only 65% of the air space between the aggregate. What we now have is 35% of 35% of air space and therefore liquid volume for storage. Here it is in numbers. In the example above, we had 262 gallons of storage capacity in the air spaces between the aggregate. Now the air spaces are filled with silt. That means we have 35% of 262 gallons of storage capacity or 92 gallons. There are many more times the cubic foot area within a drain field in a typical septic system.

Let's say we have three hundred linear feet of leach line described above. That would mean we now have a minimum of liquid storage capacity of 276 gallons. For a family of four that is most likely one day's residence time. The aggregate is surrounded with very permeable silt that will not resist the passage of liquid through it. Therefore this example of a drain field (with leach lines) would still be able to function for disposal if we were dealing with rain water or drinking water. We're not dealing with rain water or drinking water so what's the reality?

Anaerobic effluent will carry biomat producing bacteria with it into the drain field. Biomat will fill the voids in the infiltrative soils and clog the voids. These bacteria will also clog the voids between the silt particles with biomat making the silt non-permeable. Remove the biomat from the infiltrative soil voids and the silt and you now have a functional drain field.

Now we have the pitch. But a real solution. This is where the Pirana System comes into play. They both remove biomat from the silt and the infiltrative soils by biologically reducing the viscosity of the biomat slime (liquifying), thus creating permeability, and then the Pirana System will eventually consuming the biomat. The effluent that leaves a septic tank with a Pirana operating within it will not contain the biomat producing bacteria nor a significant amount of organic matter that can clog soil pores or soil voids. The effluent now has nearly the same clogging properties as rain water or drinking water though you absolutely shouldn't drink septic effluent (I know some people I believe should). Which is to say both don't clog pores or voids.

This means that the infrastructure of the drain field has value. We don't need to throw it away; or spend thousands of dollars replacing the drain field; or worry about unknown costs for landscape repair to have a functioning drain field.

I hope I've been clear and informative. I want again to increase your knowledge and widen your perspectives. In these horrific economic times saving every dollar is critical. In normal times spending a dollar that wasn't or isn't necessary should be critical.

Well thanks for stopping by and remember its out there so wipe your feet before you enter a house.