Dumping RV tanks into home syptic system

[SteveAE]

For the five or 6 years that I have been RV'ing, for convenience, I would sometimes dump my tanks into my home septic system upon returning home. While I have felt pretty comfortable doing this, I have also wondered if there was any potential for damage (to my home septic system) from this practice. So, when the tanks were especially full, I would sometimes throttle the flow so as to only allow part of the tank(s) to dump at a time. Give it a moment or two to settle, then dump some more.

Today, when I had my septic tank pumped (I do it every 5 years), I took the opportunity to raise this question with the pumper.

I learned that IF chemicals are used in the RV holding tank AND this dumping is done frequently (i.e.; > 12 times per year), then over time, these chemicals will build up in the septic tank enough that they start to liquefy its contents. If the contents of the tank liquefy (they are supposed to separate; with solids at the bottom, water in the middle, and a scum layer on top), then this "slurry" makes its way past the outlet sanitary tee (located in the center of the tank and designed for only water to pass) and into the drain field. On the other hand, if this dumping only happens a few times per year (6 to 8), then it was his opinion that it "isn't likely" to cause a problem.

When I told the pumper that I don't use chemicals at all, he responded that I "can dump as much, as fast, and as often as I want". The inlet tee will slow down the flow so as not to cause turbulence in the septic tank and the contents will be digested by the natural process in the tank (not liquefied as the RV chemicals "eventually" do).

This made sense to me so I wanted to share it with the RV community.

Happy dumping.

[kenzmad]

Turtle n Peeps wrote:

kenzmad wrote:

manualman wrote:
Hello, folks. Civil engineer here. I design wastewater systems.

Conventional septic tanks are an anaerobic environment (i.e. "septic") in which breakdown of solids into soluble substances happens on a glacial speed (SLOW). Solids build up on the bottom and grease scum builds up in a layer on the surface. If you are a low loading user, it may take a LONG time for the solids and grease buildup to get to the point where the tank no longer effectively clarifies the septage before it exits the tank and heads for the leach field. In a properly functioning system, the clearest water is in the middle elevation of the tank where the outlet pipe is. But if that outlet starts receiving greases or solids, the leach field will be destroyed (clogged tight).

NOT pumping your tank periodically until/unless there is a problem is similar in strategy to never topping off the oil on an old engine until the low pressure red light comes on on the dash. The damage is irreversible at that point.

The guy who has never pumped his tank and grinds up everything leftover on his plates either has an unsafe leach field built in soils innately made of gravel or his field is totally locked up and the flows are getting out on the surface or in a cross connected drain tile (which you'd never see).

My advice: Find out the dimensions of your tank and inspect it annually to make sure that the scum layer bottom and sediment layer top are at least a foot away from the opening to the outlet pipe (usually an elbow). Yuck. Or pay to pump it every couple of years and ask the honey wagon guy to measure for you before pumping. Increase pumping interval if its not building up much between pumpouts.

As an owner of a septic tank cleaning company, I am happy to see someone chime in here who has a grasp on how the tanks work. This has been a hard topic to read, knowing all the money these misinformed people will be spending in the future.

Since you brought up money lets talk about that for a moment.

I have no idea what you charge where you live but many, many, many years ago it was $250.00 where I live. It's now $450.00 to pump a tank and has been there for many years.

I haven't pumped my tank for 40 years in one of my houses. Now lets go low and say the average was $250 to pump my tank over the years.

Now $250 a year times 40 years is $10,000 grand!! 10 GRAND! At the other house I saved $7,500!

So total I saved $17,500 dollars!

Now, I concede that in the future I "may" have to replace my leach field. I might even have to do it in my life time. Then again, maybe not? Nobody knows for sure, not even the experts.

I have access to a hoe, and gravel and pipe is cheap. For sure not over a couple of grand and a day labor for me.

Net gain for me? About $15,000 grand! Not to gloat but that's not a bad pay day for me!

Now I don't recommend anybody do what I do, but it works for me and it has for a long time.

I Dont normally get into the back and forth with someone who doesnt have all the information he needs but here goes. Using your numbers, you are correct that you will be losing money, however, the average recommended time between tank cleanings is around 4 years. So, using your numbers, you are saving $2500.00. Damage to your drainfield is no doubt occurring as we speak. Damage to the groundwater supplies as well. You see, a septic tank is simply a water/solid separator that allows water to flow outand the solids to stay put. As time goes on, the concentration of sewage increases in the tank becoming more and more harmful to our groundwater. Times have changed and we now look at septic systems in a different light than before. The science behind it is eye opening.

[Dutch_12078]

I have no idea of the cost, but a neighbor near our Adirondack cottage had 200 foot of leach field replaced a couple of years ago. The contractor that did the job was in and out in three days, and when they left about the only way we could tell where they dug was by a slightly different color of the grass in those areas. A few weeks later, even that had blended in. The family had full use of the plumbing while the work was being done.

[cooperrobt]

We have our septic tank cleaned every two years. I have friend who just let it slide and ended up with a clogged drainage field. The tractor that laid a new field pretty much destroyed his yard.

[CavemanCharlie]

Turtle n Peeps wrote:

kenzmad wrote:

manualman wrote:
Hello, folks. Civil engineer here. I design wastewater systems.

Conventional septic tanks are an anaerobic environment (i.e. "septic") in which breakdown of solids into soluble substances happens on a glacial speed (SLOW). Solids build up on the bottom and grease scum builds up in a layer on the surface. If you are a low loading user, it may take a LONG time for the solids and grease buildup to get to the point where the tank no longer effectively clarifies the septage before it exits the tank and heads for the leach field. In a properly functioning system, the clearest water is in the middle elevation of the tank where the outlet pipe is. But if that outlet starts receiving greases or solids, the leach field will be destroyed (clogged tight).

NOT pumping your tank periodically until/unless there is a problem is similar in strategy to never topping off the oil on an old engine until the low pressure red light comes on on the dash. The damage is irreversible at that point.

The guy who has never pumped his tank and grinds up everything leftover on his plates either has an unsafe leach field built in soils innately made of gravel or his field is totally locked up and the flows are getting out on the surface or in a cross connected drain tile (which you'd never see).

My advice: Find out the dimensions of your tank and inspect it annually to make sure that the scum layer bottom and sediment layer top are at least a foot away from the opening to the outlet pipe (usually an elbow). Yuck. Or pay to pump it every couple of years and ask the honey wagon guy to measure for you before pumping. Increase pumping interval if its not building up much between pumpouts.

As an owner of a septic tank cleaning company, I am happy to see someone chime in here who has a grasp on how the tanks work. This has been a hard topic to read, knowing all the money these misinformed people will be spending in the future.

Since you brought up money lets talk about that for a moment.

I have no idea what you charge where you live but many, many, many years ago it was $250.00 where I live. It's now $450.00 to pump a tank and has been there for many years.

I haven't pumped my tank for 40 years in one of my houses. Now lets go low and say the average was $250 to pump my tank over the years.

Now $250 a year times 40 years is $10,000 grand!! 10 GRAND! At the other house I saved $7,500!

So total I saved $17,500 dollars!

Now, I concede that in the future I "may" have to replace my leach field. I might even have to do it in my life time. Then again, maybe not? Nobody knows for sure, not even the experts.

I have access to a hoe, and gravel and pipe is cheap. For sure not over a couple of grand and a day labor for me.

Net gain for me? About $15,000 grand! Not to gloat but that's not a bad pay day for me!

Now I don't recommend anybody do what I do, but it works for me and it has for a long time.

I mostly agree with you. But, even though around here you can build your own drain field the state must check several times to make sure you are doing it just right. It can be a pain.

[Lynnmor]

I now pay $125 and have it pumped every 4 years. That's $1250 over a period of 40 years. No filthy back yard, no disrespect for others, no filth to hand off to the next generation, no backhoe, no pipes and no worries about when, (not if) the system will fail. It's all part of good citizenship.

It is no wonder that laws have been passed to force people to do the right thing.

[Turtle_n_Peeps]

kenzmad wrote:

manualman wrote:
Hello, folks. Civil engineer here. I design wastewater systems.

Conventional septic tanks are an anaerobic environment (i.e. "septic") in which breakdown of solids into soluble substances happens on a glacial speed (SLOW). Solids build up on the bottom and grease scum builds up in a layer on the surface. If you are a low loading user, it may take a LONG time for the solids and grease buildup to get to the point where the tank no longer effectively clarifies the septage before it exits the tank and heads for the leach field. In a properly functioning system, the clearest water is in the middle elevation of the tank where the outlet pipe is. But if that outlet starts receiving greases or solids, the leach field will be destroyed (clogged tight).

NOT pumping your tank periodically until/unless there is a problem is similar in strategy to never topping off the oil on an old engine until the low pressure red light comes on on the dash. The damage is irreversible at that point.

The guy who has never pumped his tank and grinds up everything leftover on his plates either has an unsafe leach field built in soils innately made of gravel or his field is totally locked up and the flows are getting out on the surface or in a cross connected drain tile (which you'd never see).

My advice: Find out the dimensions of your tank and inspect it annually to make sure that the scum layer bottom and sediment layer top are at least a foot away from the opening to the outlet pipe (usually an elbow). Yuck. Or pay to pump it every couple of years and ask the honey wagon guy to measure for you before pumping. Increase pumping interval if its not building up much between pumpouts.

As an owner of a septic tank cleaning company, I am happy to see someone chime in here who has a grasp on how the tanks work. This has been a hard topic to read, knowing all the money these misinformed people will be spending in the future.

Since you brought up money lets talk about that for a moment.

I have no idea what you charge where you live but many, many, many years ago it was $250.00 where I live. It's now $450.00 to pump a tank and has been there for many years.

I haven't pumped my tank for 40 years in one of my houses. Now lets go low and say the average was $250 to pump my tank over the years.

Now $250 a year times 40 years is $10,000 grand!! 10 GRAND! At the other house I saved $7,500!

So total I saved $17,500 dollars!

Now, I concede that in the future I "may" have to replace my leach field. I might even have to do it in my life time. Then again, maybe not? Nobody knows for sure, not even the experts.

I have access to a hoe, and gravel and pipe is cheap. For sure not over a couple of grand and a day labor for me.

Net gain for me? About $15,000 grand! Not to gloat but that's not a bad pay day for me!

Now I don't recommend anybody do what I do, but it works for me and it has for a long time.

[ryoung]

Bacteria eat the solids and the result is liquids and gasses.

Not all of the solids, some remain and settle as sludge to the bottom of the tank. Then you have the grease and scum that collects on top. Both need to be removed periodically by pumping.

The following has been copied from the MassDEP website.

How Often Should I Pump Out my Septic Tank?

Regular maintenance is the single most important consideration in making sure your septic system, whether it is a conventional septic system, an innovative/alternative (I/A) system, or a cesspool, works well over time.

Regular pumping helps prevent solids from escaping into the drainfield and clogging soil pores. While pumping frequency is a function of use, MassDEP recommends that systems be pumped at least once every three years for homes not having a garbage disposal. If the home's system has a garbage disposal, it should be pumped every year.

If you are a nonresidential system owner, you should determine how often to pump based on prior accumulation and pumping records. Often you can look at pumping intervals to gauge your pumping schedule (i.e., previously did you wait too long before having your tank pumped and it was filled to capacity, or could you have waited a little longer to pump?).

An amazing number of system owners believe that if they haven't had any problems with their systems, they don't need to pump out their tanks. Unfortunately this is a serious and sometimes costly misconception. As your system is used, solid materials settle to the bottom of the tank, forming a sludge layer. Grease and lightweight materials float to the surface of the septic tank as scum.

Normally, properly designed tanks have enough space for up to three to five years' safe accumulation of sludge. When the sludge level increases beyond this point, sewage has less time to settle properly before leaving the tank. As the sludge level increases, more solid wastes escape into the soil absorption system (SAS). If the SAS becomes so clogged that it cannot absorb liquid at the rate at which it enters the tank, the plumbing will "back up" or unsanitary wastewater will bubble to the surface.

When hiring a pumper, be sure the local Board of Health has licensed them, and always make sure you get a paid receipt from the pumper that spells out the details of the transaction (how many gallons were pumped out of the tank, the date, the charges, and any other pertinent results). Retain this receipt for your records. The pumper sends a copy of this report to the local Board of Health.

ryoung

[kenzmad]

manualman wrote:
Hello, folks. Civil engineer here. I design wastewater systems.

Conventional septic tanks are an anaerobic environment (i.e. "septic") in which breakdown of solids into soluble substances happens on a glacial speed (SLOW). Solids build up on the bottom and grease scum builds up in a layer on the surface. If you are a low loading user, it may take a LONG time for the solids and grease buildup to get to the point where the tank no longer effectively clarifies the septage before it exits the tank and heads for the leach field. In a properly functioning system, the clearest water is in the middle elevation of the tank where the outlet pipe is. But if that outlet starts receiving greases or solids, the leach field will be destroyed (clogged tight).

NOT pumping your tank periodically until/unless there is a problem is similar in strategy to never topping off the oil on an old engine until the low pressure red light comes on on the dash. The damage is irreversible at that point.

The guy who has never pumped his tank and grinds up everything leftover on his plates either has an unsafe leach field built in soils innately made of gravel or his field is totally locked up and the flows are getting out on the surface or in a cross connected drain tile (which you'd never see).

My advice: Find out the dimensions of your tank and inspect it annually to make sure that the scum layer bottom and sediment layer top are at least a foot away from the opening to the outlet pipe (usually an elbow). Yuck. Or pay to pump it every couple of years and ask the honey wagon guy to measure for you before pumping. Increase pumping interval if its not building up much between pumpouts.

As an owner of a septic tank cleaning company, I am happy to see someone chime in here who has a grasp on how the tanks work. This has been a hard topic to read, knowing all the money these misinformed people will be spending in the future.

[CavemanCharlie]

manualman wrote:
Oh, and go ahead and put your RV dumpout into a cleanout upstream of the septic tank. Best not to dump directly into the tank hatch or you'll churn up the scum layer (bad). REALLY bad to dump into a line downstream of the septic tank. Know your system and use it right.

The small amount of formaldehyde in a properly dosed RV black tank isn't going to sterilize a septic tank. That's not a big worry. Your home dishwasher detergent is probably a bigger threat to the tank health (and that's not a huge worry either unless you got your dishwasher used when the Ponderosa buffet closed down....).

Thank you for clearing this up.

[Paul1944]

Being proactive is the best bet, I Rid-X my septic every other month.

[manualman]

Oh, and go ahead and put your RV dumpout into a cleanout upstream of the septic tank. Best not to dump directly into the tank hatch or you'll churn up the scum layer (bad). REALLY bad to dump into a line downstream of the septic tank. Know your system and use it right.

The small amount of formaldehyde in a properly dosed RV black tank isn't going to sterilize a septic tank. That's not a big worry. Your home dishwasher detergent is probably a bigger threat to the tank health (and that's not a huge worry either unless you got your dishwasher used when the Ponderosa buffet closed down....).

[manualman]

Hello, folks. Civil engineer here. I design wastewater systems.

Conventional septic tanks are an anaerobic environment (i.e. "septic") in which breakdown of solids into soluble substances happens on a glacial speed (SLOW). Solids build up on the bottom and grease scum builds up in a layer on the surface. If you are a low loading user, it may take a LONG time for the solids and grease buildup to get to the point where the tank no longer effectively clarifies the septage before it exits the tank and heads for the leach field. In a properly functioning system, the clearest water is in the middle elevation of the tank where the outlet pipe is. But if that outlet starts receiving greases or solids, the leach field will be destroyed (clogged tight).

NOT pumping your tank periodically until/unless there is a problem is similar in strategy to never topping off the oil on an old engine until the low pressure red light comes on on the dash. The damage is irreversible at that point.

The guy who has never pumped his tank and grinds up everything leftover on his plates either has an unsafe leach field built in soils innately made of gravel or his field is totally locked up and the flows are getting out on the surface or in a cross connected drain tile (which you'd never see).

My advice: Find out the dimensions of your tank and inspect it annually to make sure that the scum layer bottom and sediment layer top are at least a foot away from the opening to the outlet pipe (usually an elbow). Yuck. Or pay to pump it every couple of years and ask the honey wagon guy to measure for you before pumping. Increase pumping interval if its not building up much between pumpouts.

[Turtle_n_Peeps]

NJRVer wrote:
To all who haven't pumped their tanks in 30-40 years, I wonder if you actually have a "tank". They were not that common back then and you may actually have a cesspool (bottomless).

I have no idea what other people have but I have tanks. How do I know? I put one in about 30 years ago and the other one in 1974.

[NJRVer]

To all who haven't pumped their tanks in 30-40 years, I wonder if you actually have a "tank". They were not that common back then and you may actually have a cesspool (bottomless).