What's the straight dope on septic tanks?

Next week, I’m moving to a house with a well and a septic tank instead of city water and sewer. I’ve never lived with a septic tank before.

I’ve heard all sorts of stories about how delicate a septic tank is. I’ve heard never install an in-sink garbage disposal to a septic system, never flush feminine hygiene products (septic systems were obviously designed by men!), never put any food type stuff down there, etc. etc. Everything seems to state that the biological balance of a septic system can get out of whack from food quite easily.

However, I don’t see anything that warns against dishwasher soap, laundry soap, bleach, etc. Seems to me that bleach can’t be good for whatever bugs are in the septic system, but don’t see anything that warns me about this.

Here’s what I’d like: I wanna be able to put whatever I want in there, be it feminine products, the crap from a garbage disposal, or bleach. I’m willing to pay to have the thing pumped once a year if I can just not worry about it. Is this possible, or am I gonna screw up the whole system?

I’m not a plumber, but I grew up with these things:

Essentially a septic system dumps your household waste products into a large “tank” (concrete square sunk in the ground). This then feeds out into your yard. Generally there are a number of tracks that the no longer “raw” sewage seeps into. It is here that it evaporates or is taken back into the eco system.

What happens when it gets gunked up? It really isn’t just a matter of “pumping it out”. That’s the easy problem. The bad problem means digging up the entire yards and then digging out all of that crap.

You don’t want to flush things like tampons because you’re essentially flushing that piece of plastic, etc. into your back yard, where it won’t degrade.

Vegetable matter from a disposal is a different situation. Depending on how far out in the country you are, ground up veggie matter can be very attractive.

Laundry products? Most shouldn’t be a big deal. However, if you over do it, I remember seeing a sudsy lower yard because someone had over soaped the washer.

Your well also has to be well separate from you septic overflow. For obvious health reasons. And hope it’s a good well that doesn’t go dry. . .or you’re back to a sistren, with the rain water that flows off of your roof; or water hauled to you regularly.

There are more modern bio-balancing products than there used to be. But ain’t nothin’ goinna eat through those plastic flushes.

I used to live in Maine and had a septic system. We had a garbage disposal, but we never put large amounts of stuff down it because this material can get cause the septic field to clog up. The previous owner of the house had done this and as a result she had to put in a new septic field before we bought the house (nasty smelly black stuff was oozing out of the ground above the septic field). Scrape your plates in the garbage can prior to cleaning them in the sink or you can start a compost heap for your garden.

We used liquid soaps for the dishwasher and laundry; apparently the crystal detergents can stick together and form large floating chunks in the septic tank (what the septic tank guy told me).

Also try to keep your use of ammonia to a minimum; this can kill the bacteria in the septic tank that are breaking down the material that is in there. Paint or paint thinner is also not a good idea. Feminine products are also not a good idea. Toilet paper is OK, paper towels are not.

Pumping the tank in Maine costs about $75 if the guy doesn’t have to dig. It pays to know where the portals are for your tank and dig them up before he gets there. I really don’t think you need to have it pumped yearly; I had it done about every three years with no ill effects.

Hope this helps!

I just did the same thing myself. Never had one before, and don’t know much about the natural balance thing. I do know that the more solid gunk you put down there, the more likely some kind of pipe is to get jammed-up, and those things cost a lot to get fixed.

Also, don’t flush Kleenex. They don’t degrade in the same way as toilet paper.

I took a class in septic system design last year and this information is from the class and workshop manual.

Houses with in-sink garbage disposal systems have a larger tank than houses without a disposal. If the house was built with a disposal, it is a pretty good assumption that the tank was designed with that in mind. It is not good to add a disposal to a house after the fact if one was not considered in the design.

Most of the human waste (feces and urine), residual food, and to a degree, toilet paper, will liquefy and can flow into the drain field where it is broken down by microbes. More solid stuff, such as washing machine lint, will stay in the tank and fill it up. That is what is pumped, generally every two years. While it is recommended not to flush tampons (see below) and pads, it will not hurt the system and will just need to be pumped more often. (My wife flushes her items and we have a septic system, but then again we haven’t lived there long either.) I would not worry about it, unless you are in a house with a number of women who are disposing that way. The tank has baffles that keep floating materials from getting into the drain field, and heavier stuff sinks to the bottom.

As for “food-type stuff” and soaps, they are included in what septic systems are designed for. Just use some sense and don’t go overboard. Same with bleach. Small, normal use amounts are diluted enough by water to not cause a problem with the bacteria. But I would not go and dump a whole gallon of bleach down the drain.

But, here is the official word from the University of Minnesota workshop manual:

“Do not deposit coffee grounds, wet-strength towels, disposable diapers, facial tissues, cigarette butts, feminine hygiene products, and similar non-decomposable materials into the sewage system. These Materials will not decompose, and will cause a rapid accumulation of solids in the septic system.

“Avoid dumping cooking fats or grease down the drain. This material may plug sewer pipes or build up in the septic tank and plug the inlet. Keep a separate container for waste grease and throw it out with the trash.

“If a garbage disposal is used, septic tank capacity must be at least 50 percent greater that that required for dwellings or other establishments without disposals…

“Detergents can cause problems with septic systems. It is very difficult to estimate the amount of cleaning power required for a load of laundry and people generally use more than is actually needed. If the automatic washer discharges a large amount of suds after the washing cycle, the amount of washing products should be reduced. Bleach is toxic to the bacteria in the septic tank, so excessive use may be harmful. One to three cups of bleach per week added to a residential system should not be a problem.”

Good luck and enjoy the new place!

I worked for the Commonwealth of Virginia doing environmental policy work - part of my job was to assist in the development of wastewater regulations (including standards for septic systems).

When wastewater leaves your house, it goes into the septic tank where it is held until the amount of flow reaches a certain level in the tank. It then feeds in the distribution box and from there out into the distribution lines. The wastewater seeps out of pores in the distribution lines and, as it percolates through the soil, is cleaned and filtered. It then joins up with the groundwater.

Your septic system is full of bacteria that like nothing better than to eat the waste products from your house. As they do this they help break down the material and, through the process, they release gas (methane and others). That’s why you NEVER stick your head into an uncovered septic tank (there are plenty of other reasons, but that’s a big one). You DO NOT need to add any sort of bacteria to your tank (Rid X, etc). They are wastes of money.

Depending on the design of your system and the quality of the soil, the lines may become clogged. This usually happens when the wastewater fails to flow completely to the end of the line and, instead, percolates through the line too quickly. The soil under the lines becomes more and more clogged with bacteria, waste particles, etc. and less and less of the line is used. Eventually, the wastewater will not percolate at all and you have a septic back up. Wastewater on top of the ground is the usual symptom. You can prevent this by having a pump installed on the system that pumps the wastewater to the end of the line and ensures efficient use of the full length of the pipe. Here in VA, in the Chesapeake Bay watershed, you are also required to have your septic tank pumped once every five years.

Grease, paper towels, napkins, sanitary products, and other paper products (except toilet paper) should never be flushed. They clog the system and create havoc. Normal amounts of household cleaners (bleach, etc.) are fine. The bacteria recover pretty quickly.

The cost of pumping the tank varies (about $150 here from what I recall). The majority of the cost is usually the result of having to locate and uncover the tank (the pumping is a pretty quick deal).

Repairing or replacing a failed system can cost signifcant amounts of money. If your lot is so small as to not be able to accomodate another complete drainfield, you have to dig up all of the soil that will no longer percolate, truck in new soil, reinstall the lines, cover the lines again, and plant the lawn all over. You don’t want to do that - take care of the system you have.

Also, keep hydrophylic trees (maples, beeches, willows) away from your drainfield. Their roots will get in the line and ruin it.

I work for a state environmental agency and have had to inspect far too many septic tank replacements. Rule of thumb - don’t put anything in the system that won’t degrade easily. Remember that this includes condoms. Maybe it’s just cause I worked in a college town, but you would not believe the number I’ve seen in the open systems! They basically act as a water balloon that doesn’t ever deflate. Causes lasts of systems to fill up.

And believe me, you want to avoid filling these things up quickly. The smell from an old septic tank is the worst on the planet.

What is done with the ‘stuff’ that is pumped from a septic tank?


It is SUPPOSED to go to a municipal wastewater treatment plant. Based on the court cases I’ve seen, some unethical pumpers just pump it into any receiving channel and hope they don’t get caught.

I can’t let this thread go by without mentioning the name of the truck that pumps out your tank - the Honey Truck. :smiley:

Typically Septic Waste is hauled to a sewage treatment or wastewater treatment plant and is processed there. (Odd note: the pumper trucks that haul septic waste are nicknamed Honey Pots in the South.)

Thanks, or should I say tanks?

Back in the mid 1950’s when I lived in Germany as an Army brat ‘honey wagons’ were quite the norm. They used human waste to fertilize their crops. Donno if that’s still done. Understand it’s illegal in the U.S. for health reasons.

I think the soil and other factors have a lot to do with a septic system also. Our house is about 15 years old and the septic system has only been pumped once. We put all kinds of feminine products and also food waste into our garbage disposal.

If you plan to have it pumped a lot, then I would place some kind of marker where the access point is in your yard, like a rock or something.

“They used human waste to fertilize their crops. Donno if that’s still done. Understand it’s illegal in the U.S. for health reasons.”

Nope. Treated sludge from municipal wastewater systems (“biosolids” as the industry likes to call it) is a perfectly legal, and often used, fertilizer in the United States.

Do you know if there is any problem with a septic system that has been unused for an extended time (10 months)? We bought a house that long ago but won’t move in for a few more weeks, due to a remodeling job. I’ve only run a bit of water down the drains to keep the traps from going dry.

Shouldn’t be a problem. I just moved into a brand new house, with a septic system that had never been used. We haven’t had any problems - the bacteria are naturally present in the waste stream and seem happy.

OK, so I still don’t understand what would be the problem with putting anything I want into it as long as I get it pumped it out regularly. I can see where years and years of flushing everything you can think of and never cleaning it out could result in a really yucky mess, but I don’t think this applies to us.

The house was built in 1999. The septic will be pumped before we take posession as part of the purchase agreement. As far as I know there’s no issue with finding the valve. We’ll ask the owners where it is when we move in as they presumably know since they had to have it pumped.

Also - there are some garbage disposals out there that are made to work with septics. They have some sort of additive you put into them. From what I’m reading here, additives are silly. Should I just put in a normal garbage disposal instead of one of these special ones?

Slogan of a company that pumps out septic tanks and holding tanks (holding tanks are just that, tanks that hold the waste - they are used in areas that don’t have good soil (solid rock for example, and I think the soil can drain TOO well))

Royal Flush Sanitation - Because a Royal Flush beats a Full House

I’ve seen several plumbing companies in Los Angeles and Las Vegas that use the slogan “because a flush beats a full house.” I never really understood the whole thing – the flush part is obvious, but “full house”? Why would your house be full if you don’t have a working toilet? Perhaps they mean that unless your bathroom facilities work, you’ll be forced to watch old episode of Full House until they get fixed. Yeah, that’s it!