Not long after I posted my recipe for Homemade Laundry Detergent, my septic tank began to overflow onto my lawn! Oh dear! I frantically looked through my records to see when it had last been pumped only to find it had been done last in June of 2007. Because we are a large family and are home all day contributing to the contents of the septic tank, it had been recommended that we pump every 2.5 to 3 years. I faithfully wrote the date of the last pumping on the last page of each year's calendar in order to keep track. But I guess I forgot to be faithful, because it wasn't on last year's!
The septic tank was 1.5 years overdue for pumping and had several hundred extra gallons to pump. When the septic man pumped it, he found that the reason for overflow was a clogged filter. I asked him what he felt had contributed to the clogging, and he described the clogging as "fibrous," which he said is most often attributed to garbage disposal use. Anyone who has a septic should know that garbage disposals are a big no-no, as they inundate the septic tank with more organic matter than the poor little bacteria can deal with in a timely fashion. I was guilty of using it to clear out any stray food that had fallen into my drain beyond my sink strainer. I asked him what else he noticed about the filter, and he said he noticed "little white flecks" all over it, which he hadn't encountered before.
This is what gave me a red flag regarding my homemade laundry soap. I don't know if it is what was causing those white flecks, and if those flecks caused the clogging, but I don't want to find out by having to replace a failed septic drain field, so I am changing my recipe. I asked the septic guy if he thought any of my ingredients sounded like a problem, and he said that powders were the main thing he had problems with in detergent. If they are not fully dissolved, they cake in the septic, becoming like rock. i didn't know this at all, and have used powdered dishwasher detergent for the 7 years we have lived here. I have also used powdered laundry soap in the past. I was thinking of switching to using the dry version of the typical homemade laundry soap recipe, but no more. In my new recipe, I was certain to check that the powders I used were completely dissolved when I was finished. I do know that I've seen anecdotal evidence all over cyberspace that many people have used the standard homemade laundry soap recipe with little incidence to their septic, but I also see that no one seems to know if it if for sure septic safe. I have seen several incidences of people having major problems with soap flakes clogging their septic fields and causing them to fail. This is enough to make me cautious.
It is also a common rule of thumb for septic system maintenance that fats and greases should not be sent into your septic tank because they can clog inlet drains and don't degrade quickly. One of the main ingredients in the homemade laundry detergent recipe is Fels Naptha Soap/or Zote soap. Soaps are made with oils or fats, and should probably be avoided in excessive amounts, such as is used laundry for 7 people! I could not find specific documentation in what sorts of oils or fats are used in the soaps in these recipes, but by virtue of them being soaps, I am assuming them to be less septic friendly, because oils and fats don't degrade quickly in septic tanks and can cause problems.
So, without further delay, here's my recipe, partially based on what another gal I read about online is doing to avoid using soap in her homemade laundry detergent. Sorry, I can't find her post, but if you do, please post it in the comments for me.
Homemade Laundry Detergent
2 cups Washing Soda
1 cup Borax
1 cup citric acid
Fill 5 gallon bucket half full with warm water. Dissolve Washing Soda and Borax in water by stirring thoroughly. Fill to about 2 inches from top, then add citric acid, stirring again. A fizzing reaction will happen when the citric acid reacts with the washing soda, creating carbon dioxide and sodium citrate, another compound that is often added to many green detergents and shampoos as a chelating agent (meaning it takes up the hard water metal ions in water.) Don't worry, it doesn't overflow. It just makes a cool fizzing action and is done. Then, add a little more water if desired, and you're done. Use 1 cup per load for sparkly clean clothes.
The recipe is essentially my previously posted recipe, but doubled, with no bar of soap, and with citric acid added. Citric acid is used in detergents to break down food and hard water films. I added it out of experience with homemade dishwasher detergent recipes. Vinegar can have a similar, yet less productive effect. I talked to a chemist friend, because I had noticed that a lot of non soap based detergents used enzymes to break down food stains, and I wondered if citric acid could be used instead. I also was concerned that I would lose the full effect of the citric acid because of the fact that citric acid and washing soda react in solution, forming sodium citrate and carbon dioxide.
Here's what he said:
"It takes four to five one hour lectures in freshman chemistry to get the concept of how weak acids like citric acid and vinegar (AKA acetic acid) interact with strong bases like NaOH (the masochist out there can Google Acid Base Equilibrium). Bottom line here is that this effect is not negated since a fair amount of the desired component exists in solution. The underlying questions is what in this mixture is doing what. In order to keep a septic system clean and functional you need bacteria to digest the organic materials. Things like citric acid will do this by breaking down the proteins and polysaccharides into component amino acids and sugars which the bacteria use as a food source. The use of enzymes is sometimes preferred since the enzymes can do this much faster than simple acids."
So essentially, my solution should work very well both as a detergent and for the health of my septic system, because I have 4 things working for me in solution: Washing Soda (deemed septic safe on the manufacturer's website, and acting as a grease cutter), Borax (which is deemed septic safe on the box, useful in cleaning, deodorizing and brightening clothing), Citric Acid, which, as my chemist friend said, breaks down proteins and fats common in food stains, and making them more easily digested by my septic tank bacteria, and Sodium Citrate (because of the chemical reaction between the Citric Acid and Washing Soda), said to be biodegradable and septic safe and used as a chelating agent to bind with the minerals in my hard water, so that the rest of the ingredients can do their job.
Here's a great link to directions to make your own enzymes from orange peels, thus saving money on citric acid, and giving your detergent and septic an extra boost, by breaking down the proteins and fats faster. My chemist friend said he would assume that, strained, you could use it cup for cup as a replacement for the citric acid. I plan on doing this while I use up my citric acid I ordered, as it cost me $4.56 per pound. I have also considered possibly using commercial product called "lemi-shine" in a pinch. It has "real fruit acids and natural citrus oils" as ingredients. I am not sure if these would be the same as my citric acid and have no idea what they cost, pound for pound.
I hope you benefit from this recipe. I can't guarantee that it's totally septic safe, as I have only used it for a week, but from the research I have done, it seems that it is. Please use your own judgement as usual regarding what you use in your home as a detergent. For me, it works wonderfully.
Addendum as of 6/1/2011--Today at Safeway, I bought a 5 pound box of Biz Stain Fighter powder. It contains enzymes, which is the next thing I wanted to try in my detergent. I plan on adding one cup to the solution I already have, just to see if it will make a difference. My husband is wearing a shirt that, when he sweated, got a little of that old shirt smell, possibly from having been washed in the non-soap detergent. I am hoping that these enzymes in Biz will do the trick. It has been around for 40 years, and I'm pretty sure it's the detergent my husband's grandma raves about. It is biodegradable, contains no phosphates, no chlorine bleach. It is safe for septic tanks. At $7.99 a box, it should be an affordable alternative for the Fels Naptha Soap, if it only requires one cup per batch of soap. We'll see how it works, and I'll update this post.
11/11/11--I am still using ONLY this detergent for our clothes. I have changed the recipe to save Biz and Citric acid.
This is it:
2 c. Washing Soda
1/2 c Citric Acid
1/2 c Biz
Our clothes are bright! I am very happy with this formula.