How often does a residential septic system really need to be pumped out?

June 30, 2014 6:56 PM

I'm getting conflicting opinions on how often a septic system needs to be pumped, and pumping isn't cheap. My current system is about ten years old, and it's been mostly just me using it. I've heard of other low-use households that have been pumped maybe once in 30 years. Conventional wisdom seems to be thus: pump every 3 years or so or risk anything from a bad smell to a total system wipeout and replacement. Is that for real?

Of course there are variables like tank size and usage rate and whatnot, but is this "every 3 years or else" rule of thumb really true? Could a low-usage household really hold out for 30 years, or even indefinitely? Could allowing it to overfill really destroy parts of the system? Lastly, what is a ballpark fair price for such work?

posted by Camofrog to Home & Garden (25 answers total)

FWIW I've had mine pumped twice in 26 years. The ex had a habit of pouring a lot of grease down the drain, thus I'm pretty sure the first pump. Second was teenagers in the house, lol. I have enzymes that I pour down a couple times a year, especially when we're not going to be using the system a lot and give it time to work. A friend of mine had a garbage disposal and for that reason had her tank pumped about once a year. My last pump was $250 which in the giant scheme of things and house repairs was tolerable.
posted by PJMoore at 7:15 PM on June 30, 2014 [1 favorite]

Here are some good guidelines from NC State.

Various members of my family and I have owned an old house in upstate NY for close to 40 years. The septic system is ancient, we've had it pumped maybe once, about 25 yrs ago. If it's working fine leave it alone.
posted by mareli at 7:18 PM on June 30, 2014

It probably depends on the size of your tanks, the amount of water you use, garbage disposal use, etc.

Septic system dude said 3 years was appropriate for ours; he said he would not go any longer than that (tanks were nearly full).

Check your local laws, too. Sometimes they require inspections and service. My local laws say inspection every 3 years. They have a program here where you can get certified to inspect your own system (they used to just let people do it; now you have to take a class), or you can pay someone from their approved list.
posted by AllieTessKipp at 7:32 PM on June 30, 2014 [1 favorite]

Yeah if it isn't broken don't fix it. 20 plus years for my old one.
posted by GeeEmm at 7:40 PM on June 30, 2014

Yeah if it isn't broken don't fix it.

Nooooo. If the tank fills and starts sending solids to the drain field, you'll end up needing to excavate and replace the drain field, which is way, way more expensive than simply pumping the tank.
posted by ryanrs at 7:54 PM on June 30, 2014 [5 favorites]

We've had ours pumped twice in twenty years. The second time it wasn't necessary. The pipes inside the house leading to the septic tank needed attention, the tank was fine.

There are simple things to be aware of, such as using degradable detergents, toilet paper, etc.

The tanks, under the right circumstances, take care of themselves. That is to say the naturally occurring bacteria breaks down the waste.
posted by elf27 at 7:56 PM on June 30, 2014 [2 favorites]

Response by poster: If the tank fills and starts sending solids to the drain field, you'll end up needing to excavate and replace the drain field

This is what worries me. One of these is literally worth ten "if it ain't broke don't fix it" comments. How often does this really happen, a whole system getting FUBAR'd?
posted by Camofrog at 8:01 PM on June 30, 2014

I had this very conversation a year ago, as I was getting a little nervous about 17 years of living by the rule, "ain't broke, don't fix." Then a sad day came, a Sunday of course, when the tank said "oh yeah?" and backed up into the basement. It took 2 plumbers 2 very long days to clear out the clogged pipes and clean up the ugly mess. Using a bucket for that time wasn't much fun at all. The cost was about the same as if I had had the tank pumped 3 - 4 times over the years, but the extra aggravation was very uncool. As bad as it was, I felt very lucky that the tank and leach field were still OK.

I learned 2 things:

1. YES, it is generally a good idea to have a septic tank pumped periodically, before it fails. The interval will depend on your particular conditions -- 3 years would be more than necessary for most systems, but I have no intention of ever trying to push it beyond, say, 7 years. A back-up doesn't always mean that the whole system will fail and need to be replaced, but it can, and it's never fun. Not worth the risk.

2. Don't ever flush dental floss.
posted by Corvid at 8:15 PM on June 30, 2014 [2 favorites]

It's been 10 years, so it's certainly not too early to pump it out.

It sounds like you're trying to balance some kind of tradeoff here, but I don't think there is one. Waiting is not going to make the job cheaper or more convenient (just the opposite). And it's not as if septic tanks have some kind of early warning system that will alert you just before it fails. What happens is one day your toilets will stop working and then you're already in trouble. Exactly how much trouble depends on the precise circumstances, but even if you're lucky, it's still going to cost more than pumping it today.
posted by ryanrs at 8:33 PM on June 30, 2014 [3 favorites]

In my old septic tank, which I had pumped twice, mayyybe three times, in 25 years, there was a capped pipe on top, the top of which was about a foot below the soil surface. I believe that's a standard feature, because the septic tank of the house I grew up in had one, too. In fact, it has to be a standard feature--that's where the septic sucking service sticks their hose. Find that pipe, uncap it (you'll need a Very Large Wrench), and stick a disposable stick down there to test the waters, so to speak. If the solids are getting close to the top, pump. If not, check again in a year.
posted by bricoleur at 8:52 PM on June 30, 2014 [1 favorite]

This is a tough question I've been wrestling with for a while. I live in a house almost forty years old, and it's never been pumped. Apparently this is not that unusual where I live (Long Island, NY) because almost the entire island is a sand bar with some topsoil. I know it's never been pumped because there is no access hatch, the local practice is to install one after the first pump out.

That having been said, the local septic guys all recommend 3-5 years, but I can't help but think they aren't quite impartial.

Other folks have recommend "The Septic System Owner's Manual" by Lloyd Kahn. The revised edition is from 2007, it's probably worth looking through.
posted by Marky at 9:12 PM on June 30, 2014 [1 favorite]

Don't ever flush dental floss.

Good Grief! Don't ever flush ANYTHING except toilet paper and waste. Clean your toilet with a cap-ful of bleach in the water rather than caustic cleaners. Limit grease and large solids (especially meat scraps) in your kitchen. Try not to use a lot of bleach and extremely strong cleaners in your laundry. Use septic stimulant if you like right after getting it pumped to get it starting to 'brew' again.*

Beyond that, you can get away with not pumping for years, but it's a wise man that pulls the lid or has the clean out inspected every three-five years.

Four kids, two adults pumped once in twenty years. Pumped again after seven to comply with selling regulations. Didn't sell, opened the lid last year--good thing we did as we were starting to get roots in the drain field. ARRRGH! But the septic has always been at a good level thanks to extremely porous soil and a good working 'broth.'*

*These technical terms are brought to you thanks to the vivid imagination and speech of my local plumber.
posted by BlueHorse at 9:18 PM on June 30, 2014 [1 favorite]

Response by poster: 2. Don't ever flush dental floss.

[Seemed worth repeating/highlighting]
posted by Camofrog at 9:19 PM on June 30, 2014

Also: 'flushable' wipes aren't. The horror. The horror.
posted by Space Kitty at 11:22 PM on June 30, 2014 [2 favorites]

The 3-year interval makes sense as a nearly universal, erring-on-the-side-of-safety recommendation for someone who's going to rely on a calendar to make this determination. I know very little about septic systems but it seems pretty obvious that a calendar is a lousy tool for determining when a pump-out is required. Saying that it needs to be done every X years is about as likely to be correct as saying that all cars' gas tanks need to be refilled every X days. You need the septic system equivalent of a gas gauge, i.e. to do an inspection. If you want to save money then learn to do it yourself. If you're a little lacking in confidence about such things then, after you've read some how-to guides, hire someone to do it the first time. Watch and ask questions.
posted by jon1270 at 3:56 AM on July 1, 2014

Getting your tank pumped is cheap compared to nearly every other damn thing that could go wrong with a house. Should be $200-300. Just do it every 5-10 years as maintenance.
posted by gnutron at 4:53 AM on July 1, 2014 [2 favorites]

Just popping in to say that I've walked away from not one, but two house contracts because they had failing septics. The owners never felt the need to pump because there were no immediate problems, but in both cases the field was compromised and would require total replacement, which in the part of New Jersey we were looking in, can run you about $30K. At the very least have an inspection every few years! Someday you may want to sell, and it may make the difference.
posted by Otter_Handler at 5:06 AM on July 1, 2014 [2 favorites]

We bought a house last year that had a fairly new septic system, around 5 years old. Decided to get it pumped out because we needed to have the tank location surveyed anyway. The tank was apparently full of baby wipes (yeah, don't flush those!) as well as the usual "brew". So, cleaning out a tank used by a family of five (the former owners) after 5 years of use was about right. It cost us around $400. Like everyone says above, it's certainly better to err on the side of too-frequent clean outs rather than waiting til the system fails. But for a single person, with a modern system (I assume you have a 2-part system with tank and leaching ring(s), right?), a 10-year pump out schedule wouldn't be insane.
My advice? Have a cesspool company come by, inspect it, and let them show you how full it is. Get it pumped, and decide if in the future you can wait another 10 years or if you should do it more frequently. Whatever you do, don't put it off for another 20 years then have a big party with lots of people using the bathroom. That was a party I will never forget!
posted by Jemstar at 7:21 AM on July 1, 2014 [2 favorites]

Clean your toilet with a cap-ful of bleach in the water rather than caustic cleaners

Bleach is caustic. It's usually sold diluted, but it is caustic.
posted by Neekee at 8:34 AM on July 1, 2014

FWIW, we've had our septic system pumped about once every 5 or 6 years and most recently it cost me about $400. It's a newer system with 2 large tanks underground, apparently this is the requirement for a 4-bedroom house here (Ohio).
posted by see_change at 9:17 AM on July 1, 2014 [1 favorite]

Compare to city water and sewer, where sewer costs $45 a month or about $540 a year, and your three-year pump outs become extremely reasonable in comparison for a happy little septic system.
posted by halfbuckaroo at 4:53 PM on July 1, 2014 [2 favorites]

Just what are you people flushing down the loo? We only put poo and septic safe toilet paper down ours. The bugs work on that and there is no problem. The more other stuff that does go down then the more likely you will have a problem.
posted by GeeEmm at 3:32 AM on July 2, 2014

Response by poster: I am still hoping a pro pumper will show up to explain the ins and outs of it, but in the meantime the consensus indicates it is prudent to pump sooner rather than later, so that's what I'm gonna go with. Especially after halfbuckaroo put it into perspective: not a bad price to pay for pumping out your . . . you know.
posted by Camofrog at 6:08 PM on July 2, 2014

You want two things for your septic. A healthy plant where the bugs are working and a working absorption trench where the outfall can be absorbed. The level of residue in the chamber is an issue but not a big deal unless it stops the plant working properly or more importantly it blocks the outlet as that is when you get the back up.

Just remember that the pumper makes his living out of pumping. That does not mean that you have to be the source. But if people want to use the toilet as a general waste disposal he will live well.
posted by GeeEmm at 7:52 PM on July 2, 2014

For the record, my AWWTP service guy came today. My tank (18 years) is fine, he dips it every three months when he does the service. At this rate it will last another 5-10 years, maybe forever.

To add to my comments above, he advised: The sludge at the bottom is basically toilet paper breaking down (unless you put other stuff down there). If it gets into your absorption trench, it will coat it and nothing will be absorbed thereafter. Big expense to rebuild trench (as others have said). Chemicals down the sink or loo which kill the bugs in the tank will obviously accelerate the sludge build up.
posted by GeeEmm at 6:54 AM on July 23, 2014 [1 favorite]