How often should tank be pumped out?

[mdshunk]

I've got a sand-mound septic system at my house. Pretty much becoming the "standard" system in my parts. Has been installed about 3 years. Works fantastic, and I'd like to keep it that way. I'm just not real sure how often you really need to have it pumped. On the side of a septic pump truck I saw in trafffic it exclaimed, "EVERY TWO YEARS." Yellow Pages ads seem to verify the every two years theory. This could be propoganda, I tell myself.

I know folks (with traditional gravity systems) that brag about not having their system pumped in 20 years. This is the other extreme, that seems equally foolish.

I had mine pumped at the two year anniversary. Only cost $85 for 1000 gallons. Not too bad I suppose. I'd just like to get pinned down how often is "really" required.

For reference, there are 7 in the household, 2 full baths, washing machine, dishwasher, and kitchen sink on the system. (I would have liked to put the laundry water out in the yard somewhere, but there's a stream running through the back yard. I didn't want any trouble)

[suemarkp]

My understanding of septic tanks is that water sits in there for the solids to settle and the scum to float. Bacteria then munches on the water and scum. Then the somewhat clear water exits via the distribution pipe when more water is added to the system. What you therefore need to watch is how thick the top scum layer is and how thick the sunk solids layer is. There are baffles to keep these solids from entering the exit pipe. But if they get too thick then these solids begin to exit your tank clogging the field/mound.

So open your tank and poke through the scum with a shovel. Try to determine how thick it is. Look at the exit baffle to see how low it goes. Make sure the scum is not close to the bottom of the baffle. Usually, you can tolerate about a foot of scum. Next, at the hole in the scum, put a stake to the bottom of the tank and remove it. Try to determine the thickness of the solid goop on that stake. Again, if it is about 10" high or more, you need to pump it out.

You have a modern sand mound system which may have multiple tanks. I think the first big one is the one to check. The main difference between these and the conventional gravity systems is that your tank is emptied at a more constant rate in smaller water squirts. This lets the system work longer on the effluent than in the feast or famine of a gravity system. The down side is the tank may not empty if you have a power failure, so limit water use during those periods.

For us, 3 to 5 years is about right. Two years seems excessive unless you have a small tank, a garbage disposal, or use way too much bleach.

[mdshunk]

I installed the system myself, so I'm familiar with the tank design and the piping arrangement. I just wasn't sure how to tell for sure when the tank needs pumped. The foot scum layer and the 10" solids layer helps me to know now.

I have 2 tanks. The first tank for biologic action (solids tank) and the second is the effluent tank with the pump. I put risers and 27" manhole lids on both tanks to make inspection and maintenance easy. I keep a regular eye on the pump tank. I know that if solids and scum spill over into the pump tank, that can spell DISASTER for the sand mound. I have the septic pump on the generator panel, so power shouldn't be an issue in my case. I bought an identical spare pump at the time of installation. They're not nearly as expensive as my well pump was. The pump outlet pipe has unions within reach just inside the tank, marine electrical plugs suspended inside the manhole riser, and a nylon rope on the pump bail. I should be able to change the pump in decent time without getting too messy and without having to have the effluent pumped out (which was my main intention), should the pump ever fail. I figure with 2 pumps and each one possibly being able to be rebuilt once or twice, I should be set for life in that regard.

When I had my tank pumped after 2 years, I'd estimate that the scum on top was 4 to 5 inches thick. Not sure about the thickness of what was settled on the bottom. The pump guy had 'er sucked down before I really even realized it. I was busy gawking at the fancy gadgets on the truck. Seems like from your numbers, I should be able to go 4 or 5 years without worring too much. Thanks.

[Wgoodrich]

There is no dead set year interval setting to pump the tanks. As has been discussed the contents is designed to eat itself by use of bacteria in the tank. If you pump too often it takes too long to build up the bacteria to eat enough to do the job. If you pump not often enough the solids that settle to the bottom that can not be eaten up will fill toward the top of the tank limiting the amount of area being digested by eating itself.

You need to find the half way medium. A family lives different even if the think they live like the neighbor. Eating habits, laundry and other gray water set up if included, garbage disposals etc. all affect the ability to digest.

All depends on your life style what you drain into it and how much solids are bulding up from the bottom of the tank and how fast. Each system will need to find its own time frame to pump out the tank in a cycle. Then don't forget any time something changes in life style such as kids leaving and starting their own life or grand kids moving in with you etc. can change that cycle of pumping the tank needs without notice.

Kind of like riding a bike. You will have to decide how often to pump your tank by using the seat of the pants feeling of your family life style and system design. 3 to 5 years is my best advice. Many think I am nuts. My feelings is it takes at least a year to create the digetive ensigms again to start digesting right. If you pump too often the digetion operation never gets going again.

Just my opinion to answer this question is like controlling lightening, only opinions can be offered and past experience of our own life style and system design

HOpe this helps

Wg

[mdshunk]

Your statement that it could take a year to get the biologic action going again was interesting to me. To me it begs an obvious question that could almost be another thread.

Is their any real benefit to adding "bacteria" to your system (like the stuff in the box you're supposed to flush down the commode once in a while). My sister, who lives far from me, swears by it. I don't know what she basis that on, other than the good feeling you get when you flush a batch of that stuff down. I know that the stuff is surely doing something, but is the "something" that it is doing worth the extra effort?

Additionally, some folks in my area have air pumps that constantly pump air through a little 3/8 inch hose into spargers at the bottom of the tank. This is supposedly to oxygenate the tank and promote bacteria growth. I thought that the biologic action in septic tanks was anerobic (namely, happens in the absense of oxygen). Am I right or wrong on this?

Don't know much about bacteria...Thanks.

[Wgoodrich]

In my opinion you have all the bacteria pumped into that tank from normal life use that you need. However it is much like waiting for the egg to boil. Takes time for it to start eating itself.

Key point is to watch your tank. As long as the sludge is not leaving the tank going into the finger system to plug those fingers the tank is doing its job.

What is happening is after the tank eats what it can solids then sink to the bottom creating a sludge.

When they pump that tank they pump it out then pressurize it back into the tank about three times. While doing this the high pressure re entering the tank then busts up those solids in the bottom of the tank.

The solids building up is what you need to watch. The fuller the tank with solids the less area the affluent can eat itself and produce the solids.

After a while the tank fills enough with solids resricting the area needed to eat itself and then the affluent. [liquid sludge] then overflows into the finger system causing damage.

This time frame of how fast the solids builds up and restricts the tanks ability to digest will differ for each family living traits.

To me adding bacteria to a tank that is full of bacteria already is flushing money down the drain. That affluent just needs time to cook before it can start eating itself. If you pump not often enough you can cause sludge to enter the finger system and cause damage irreparible.

To pump the tank out too often prevents the affluent from cooking enough to start eating itself.

HOpe this helps

Wg

[joed]

I have seen several tanks pumped at different loaction here in Ontario. I have never seen them blow back into the tank to flush it. Is that a USA thing?

[Wgoodrich]

If you just pump out the liquid without blowing it back in a few times to bust up the solids in the bottom of the tank you never really cleaned the tank back to new condition. You still have the solids in the bottom of your tank.

Think about having a bucket full of muddy water. Let it set for a week. Pour it out. You just did what they did when they just pumped the liquid from your tank without blowing back in. Now look at the bottom of the bucket. You will find a large amount of packed mud in the bottom of the bucket that never came out cutting down the capacity of that bucket.

Now do the same experiment. Only this time pour that muddy water after setting for a week into a second bucket. Now look in the bottom of the first bucket. You will see the mud in the bottom of the tank. Now pour that water out of the second bucket back into the first bucket again and immediatly pour it back into the second bucket from the first bucket.

Again look in the bottom of that first bucket. Pouring that water back into that first bucket then immediatly back out will flush that mud in the bottom of that first bucket floating that sedated mud. When you pour that water into the second bucket the second time again check the first bucket. You will find a clean bucket in the bottom.

That is the same principle used by pumping out the septic tank then pouring it under pressure back from the truck back into the septic tank. Repeat this action about three times. You should find much more if not all of the solids flushed from the bottom of your septic tank. Now you are back to same as new ready to start all over again.

Hope this helps shed some light

Wg

[suemarkp]

I've only watched the pumpers twice, and its not too easy to stand and look into the tank while they pump without gagging, but the practice here seems to be:

1. Suck out all you can.
2. Shoot a water hose into the tank while breaking up the sludge with a stick.
3. Suck this hose water/sludge mix out.
4. Repeat 2 and 3 until clean.

[joed]

They didn't appear to leave any solids. It looked like they had pumped down to the bottom of the tank. Maybe the tank wasn't that bad and they didn't need to back blow it.

[Wgoodrich]

May be that your tank had no hard solids in the bottom of the tank. Hope that is right. Unless you get a strong flash light and brave the smell sticking your head down in the hole to look it often will look like the bottom but is really solids built up in the bottom of the tank. Most tanks are about 8 to 10 feet to the bottom.

I have seen tanks never pumped for 20 years. Then when they were pumped the solids were so high in the tank that only about two feet was left in the tank. Hate to think of condition of their finger system. It was never cleaned out past 1/2 full of solids. It was advised that they replace the tank. Now talking about heavy, wow.

Wg

[mdshunk]

I didn't watch much of my tank being pumped out, but I know he didn't blast septic water back in. He did "wash" it out with water from a hose that is carried on a small tank on the septic pumper. Not much water was used... maybe 30-40 gallons. The hose he used to wash out the tank was about 1 1/2 times fatter than the typical garden hose (as oppesed to the hose used to suck it out, which I think was about three inches dia.) Maybe different pump companies have different methods / equipment / styles? The fellow did shine a light around inside when he was done. I didn't ask why, but I assumed that he was just checking for cracks. Seemed like a good idea to me. I'm just as much interested in knowing if my tank is cracked as the septic guy is interested in selling me a new one ;) I have concrete tanks. Others in my area use fiberglass tanks. The fiberglass tanks just seemed too fragile to me. I'm sure that they would have been just fine though. I once lived in an old farm house that had a brick septic tank that was parged inside. It was failing about the time I moved out (just renting there). That was the only brick septic tank I ever saw or heard of.

[Universlman]

Not much happens in the tank - the drainfield is where the action happens. The guy with the first reply had it right. The whole septic tank issue is full of myths. When to pump the tank? - when it needs it - no sooner. Check with the few simple tools mentioned.

By the way - of all of the additives available on the market, no university research is available to prove any value for these "enhancers", if you place any value on facts.

[Unregistered]

I've got a sand-mound septic system at my house. Pretty much becoming the "standard" system in my parts. Has been installed about 3 years. Works fantastic, and I'd like to keep it that way. I'm just not real sure how often you really need to have it pumped. On the side of a septic pump truck I saw in trafffic it exclaimed, "EVERY TWO YEARS." Yellow Pages ads seem to verify the every two years theory. This could be propoganda, I tell myself.

I know folks (with traditional gravity systems) that brag about not having their system pumped in 20 years. This is the other extreme, that seems equally foolish.

I had mine pumped at the two year anniversary. Only cost $85 for 1000 gallons. Not too bad I suppose. I'd just like to get pinned down how often is "really" required.

For reference, there are 7 in the household, 2 full baths, washing machine, dishwasher, and kitchen sink on the system. (I would have liked to put the laundry water out in the yard somewhere, but there's a stream running through the back yard. I didn't want any trouble)

85$ is a lot chaper than replacing sand in your mound which is what would happen if the solids in your tank over flow

[gbeichho]

I've seen mine pumped as well (in Canada) and they never blew back either. There was no sludge left behind. I asked the pumper how often I needed to do it, he said 5-6 years. This was for a seasonal cottage.

[DUNBAR PLUMBER]

The true rule in the area is the 1/3rd rule; never should your tank have more than a 1/3rd of solids. Anything more and you take a chance of waste products entering parts of your system that will cause problems.

[AllanJ]

If the company that pumped the tank is able to report back to you the amount of solids in terms you can understand, you can play it by ear. If you feel that the tank had a lot more room to go, allow more years before the next pumping, etc. If you just installed a sink garbage disposer you may do well to schedule the next pumping after a shorter interval.

If you just pump out the liquid without blowing it back in a few times to bust up the solids in the bottom of the tank you never really cleaned the tank back to new condition. You still have the solids in the bottom of your tank.
Wg
A septic tank pumping job is not proper and not complete unless most of the solids have been removed. How that is accomplished (water jets, recirculating the truck contents, etc.) is not important so long as that is accomplished.

Removing only the liquid and scum has no socially redeeming value. Under normal operation the tank at rest has its water level matching the lower edge of the outlet pipe which generally corresponds to something like 80% full. After pumping, proper or not, this level will usually be re-attained within a few days.

(It is not practical to remove absolutely all of the solids.)
(Some solids need to be left behind to leave "starter bacteria" to get the digestion process going again.)

My first house had a septic tank. I did the unearthing of the tank and removing the cover, and closing it up after the pumping company had finished, so I got to verify that the tank was properly pumped.