garbage disposals / septic systems

[MasterPlumbersKeymaster]

What affect does the use of a garbage disposal have on a septic system ?

[DUNBARParticipant]

Vegetative matter introduced to septic tank systems can be detrimental, especially to aging systems.

Unlike raw feces, depending on what you put down it, can take a considerable time to break down, causing the digestive process to be altered.

This can lead to solids mixing with effluent which can end up in the finger system of your leaching fields.

Bottom line, big problems and major expense at this point.

Keep a garbage can next to your sink when preparing meals, not using your plumbing system as a garbage can.

The golden rule of plumbers:

Only what passes through your body, with the exception of toilet paper, is the only thing that should enter a drainage system.

[Retired plbg1Participant]

Dunbar is right, I dont grind anything in mind I put it out for the animals.

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Art retired plbg

[DUNBARParticipant]

Thanks for chiming in on this racefanone, and no one is going to delete your post. You bring up valuable points and I plan to clarify on the golden rule.

As a plumber, drain cleaner, and troubleshooter of the trade for over 17 years, I along with others in the trade gauge the cause and effect of plumbing related situations that prove costly to the property owner over time.

Thanksgiving is soon arriving, and the most common call on this day makes me very thankful; clogged garbage disposals. People shoving everything they can grind in a hurry, not thinking of the result.

The improper use, the lack of adequate water during this grinding can cause backups not only in the local piping, but numerous feet on down the line. As I repeat, Raw feces can break down at different stages, but has a faster liquified stage than say apple rinds, celery stalks, potato peels. People put melon rinds, cucumbers, egg shells, uncooked rice thinking it will take everything you shove in it.

All of these things mentioned above, haven’t entered the digestive system of a human body first, breaking it down into fecal matter. Even with the different solids of human matter that we know of, they all break down over time, and raw fecal matter never consititutes the question posed if it should or should not be a good idea to flush.

In regards to your statement to shampoo’s, toothpaste, and the like, these items are relevant, but not done in excess in any fashion that brings safeguards to their use. Never have I heard of any in my years.

I talk of the solid matter; toilets clog when there is excessive toilet paper. Anytime you alter the water to solid ratio in a toilet, you instantly have a clog. Water is necessary for the flush, and what happens in most garbage disposal clogs is usually the lack of water, too much matter at one time.

Anytime you introduce large amounts of vegetative matter to any system that doesn’t have adequate water flow behind it, you have problems, and they cannot be isolated to the plumbing system inside the home, it travels out to the septic system.

People keep me employed by dumping anything they can get away with in the drainage system. Ignorance dictates the thousands of dollars drain cleaners generate in any given year.

John Aldrich is the educated professional on this board that knows this topic very well, and I expect when he see’s the red carpet I am rolling out for him, he will offer his opinion on the matter.

A pondering thought:

If you go through the list of vegetables, items people throw into the drains, think of the items/products/vegetation that floats or stays water-born and takes a consider amount of time to settle into the bottom of a tank.

Now, take the configuration of a simple 3 bay 2 baffle septic tank and understand that there is a inlet and outlet pipe. If vegetative matter does one or the other, overloads the tank and disturbs the digestive process, or floats over the 2 baffles and continues to leaching fields, you have a major problem underground. Major being call backhoe joe he’s coming with a price tag.

The diagnosis, the repair, the remedy will be to discontinue the use of a garbage disposal to prevent the disturbance of the system. All systems are different, and adding a disposal can be destructive. If they cause problems with systems that are new connected to city sewers, they definitely offer more problems to a septic system.

The market followed this idea by making a disposal that injects a product that speeds the breakdown of vegetative matter. Still doesn’t keep the problems away.

» This message has been edited by DUNBAR on 18 November 2004

[John Aldrich1Participant]

veyz, this subject has appeared on this Bulletin Board and other plumbing discussion forums many times. I have pasted one of these inquiries from “estowers” and my response to his inquiry.

Author: estowers (MT)

Hello!

We were told that since we had a septic tank, it was unwise to put in a kitchen disposal, even the kinds that deposit special bacteria for the decomposing, since the food products will over time ruin our septic tank and plug up the pipes with sludge. Is that true?

Septic Tank Yank wrote:

Estowers,

This question is a recurring one on the Plbg.com Discussion Forum, so I hope that my answer is consistent with my previous position on the issue. Typically, I advise my clients to avoid the use of a garbage grinder that discharges to a septic tank system. I recommend the use of a compost pile for aerobic digestion of the vegetable matter constituent of their garbage. The meat, fat and bones in garbage goes into the trash to be collected and landfilled.

An exception to this rule is when the home is located in Bear Country. Bears are attracted to compost piles. In this situation, then I recommend the use of garbage grinders as a method to safely dispose of the vegetable matter. The downside of this approach is that the frequency of septic tank sludge removal is increased dramatically. The sludge layer in the tank accumulates rapidly when undigested vegetable matter is applied. Microbial digestion is just much slower with raw vegetable matter.

The reason sludge removal is important in a septic tank is that as the sludge layer increases in depth the hydraulic detention time of the sewage in the tank decreases. The velocity of the sewage flow increases leaving less time for microbial digestion of sewage solids. The suspended solids flow out of the tank and are applied to the leach field. This causes clogging of the holes in the distribution pipes of a typical gravel and pipe leach field, and causes organic overloading and clogging of the soil at the bottom of the leach field. The clogging mat ultimately grows in thickness to the point where the percolation rate of the effluent through it is less than the rate of application. When this occurs, the effluent either surfaces or backs up into the tank and into the house.

As for the frequency of sludge removal, I recommend the “1/3 RULE OF SLUDGE REMOVAL.” When the measured sludge depth in the primary chamber of the septic tank attains 1/3 the total liquid depth of the tank, it is time to remove the sludge. Selection of an arbitrary interval of time for sludge removal is simply not appropriate. Each septic system is unique and sludge accumulation rates vary greatly.

So estowers, “You pays your money, and you takes your choice.” Go ahead and use your garbage grinder if you live in Bear Country, or if that is the life style that you choose, after all this is AMERICA, the land of the free. (At least the last time I checked, Montana is still part of America) Just realize the price that you will pay for this freedom is the cost of more frequent sludge removal from your septic tank or the cost of a new leach field if you avoid the responsibility of sludge removal.

[Retired plbg1Participant]

You are all right with your points, I have used a septic tank for 10 yrs. and I dont grind up a qt. of stuff a yr. into tank, I fig. the animals can eat it I live on 6 ac. of land and the animals come around all the time.

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Art retired plbg

» This message has been edited by John Aldrich on 20 November 2004

[nicktheplumberParticipant]

I have posted on this topic in the past (check the archives). My opinion is that garbage grinders represent one of the most unfortunate marketing ideas that have been foisted on consumers. I don’t care if your waste goes into a municipal sewer or septic tank…you just should not grind your garbage into the kitchen sink. You should put good quality strainers in your kitchen sink to catch the solid waste and put the stuff the strainer collects into a garbage can, to be thrown out with the rest of your garbage. Even if you live in “bear country” this rule applies. After all, you do generate other garbage and it must be disposed of, right?

I have very reluctantly installed garbage grinders for those who insisted on them, but in all cases I have admonished these customers to strain their sink waste and put it in the garbage or a compost heap, and to view their garbage grinder as a sort of additional filter to deal with the occassional and unavoidable times when garbage somehow got past the sink strainer.

NtP

[Author]

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