We often see RVers give advice that dumping holding tanks at home is not a problem—even into septic systems—rather than a city sewer system. Here are a couple of points to keep in mind:
Home septic systems are generally tasked to handle a relatively low flow of sewage over a period of hours. Dumping a large amount of RV waste at once could lead to disturbing the layer of sludge in a home septic tank—possibly causing it to break up and move out into the leach field. That can lead to an expensive clogged system. If you have both full black and gray water tanks, it might be best to dump one at a time, spacing the dumping out over a couple of days.
On another note, here’s a comment from the U.S. Environmental Protection Agency: “When chemicals, such as formaldehyde, are added to septic systems, they can cause bacteria in the system to die. When this happens, the septic system cannot treat waste adequately. Solids that are allowed to pass from the septic tank, due to inadequate or incomplete treatment, may clog the leach field.
“Furthermore, clogged systems may send inadequately or incompletely treated sewage to the surface, threatening the health of people or pets who come into contact with it. Or it may percolate to groundwater, where the chemicals and untreated wastewater could contaminate nearby drinking water wells, rivers and streams. Please read labels carefully to identify any hazardous ingredients.”
What constitutes “hazardous ingredients”? Formaldehyde: An active ingredient in some
deodorizers, also called Formalin. Formaldehyde is an EPA-recognized probable carcinogen (i.e., causes cancer). Paradichlorobenzene: Known carcinogen and drinking water contaminant. A common ingredient in mothballs, urinal cakes and bowl fresheners.
One more thing: Should you decide to “build your own” dump station at home, BE SURE your dump port is installed between your home and the septic tank. Don’t be like the RVer in Washington state who put his between the septic tank and drain field. He learned a very expensive lesson!
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The article asks a question then has lots maybe’s, might’s, could’s, etc. and cautions about possible problems with chemicals in the septic and sewer systems. Apparently there is no answer which makes me wonder what do the parks we use do to safely handle the yech? I’m sure they’re not all the same.
Parks on septic tanks generally ask (or require) that you not add chemicals and particularly not formaldehyde.
When we originally bought our house we were on septic. Miraculously, when the septic system died, the city was running sewer pipes down our street, Whew – talk about dodging a bullet. After we bought our first trailer, we had a ‘dump site’ installed which has made life easier just in case our last stop didn’t have a dump. For those who advocate putting no chemicals in your black tank, would it not be OK to dump into your septic tank?
I have used city sewer connections at home while parked at others house’s and our own house before with no problems. I would never dump raw sewage into a possibly overloaded septic system. Just use lots of water to follow up.
True, you probably shouldn’t dump into an unknows septic system, and especially should NOT use lots of water since the capacity and condition are not known. The waste will break down with proper bacterial action, too much water may wash it out into the drainfield too soon.
Most RV parks use (admittedly large) septic tanks and fields. Most of the RV holding tank chemicals I see on the shelves are specifically marked septic system safe. I’ll admit I wasn’t thinking about the risk of the sudden large inflow disturbing the sludge in a household septic system.
Our 1906 home has a ground level air vent (in addition to the main stack through the house) just outside the house and ties into the city waste system at the curb. I purchased a macerator and industrial 3/4″ hose. I often park at the curb and using the macerator, dump into that air vent. The volume isn’t a lot different than flushing a toilet in the house, just continues a lot longer than a toilet.
I would guess that most people who dump into their stick house city sewer are doing that through the sewer clean out. The article did not answer the question whether this is a good idea or not.
Just food for thought on dumping your waste tanks in your septic system.. I have a septic system that has been in use for over thirty years and have been dumping my tanks to it regularly for all that time. I’ve never had a problem and, in fact, it’s never even been pumped out! I’ve reasoned that it’s actually being helped by the fact that I’m adding a new infusion of ‘good bacteria” to the system regularly! My dump station is at one end of the house and is the farthest input to the system, ie, it runs the entire length of the house to the other end. The septic system has no leach field (not enough space to the property line). It uses a 80 foot deep dry well as we live in AZ. No formaldehyde
It’s a good article. Chlorine can have a detrimental effect in septic systems. I wouldn’t use any product in an RV holding tank, because it just isn’t needed and can cause problems. Lastly, the point about disturbing a septic tank is good advice. A high volume and high flow can lead to problems. Just release as gently as possible, or if worried about leaving behind solids in the RV tank, release wide open for a very short and partial dump. Wait, repeat.
If your septic tank system is in good condition, there is no reason not to dump RV tanks into it, provided that you have not used any chemicals that you don’t normally use at home. As long as the baffles at the tank outlet are in good shape, there shouldn’t be a problem. Septic tank systems are generally designed for 100 gallons per day per person, or the equivalent per bedroom, so dumping even the larger RV tanks shouldn’t overload them and if no chemicals have been added the bacterial action in the tanks is similar to that in the septic tank so that shouldn’t be a problem either. The waste is slightly more concentrated since most RVs have fairly extreme water conservation features.
You can’t really dump your RV tank fast enough to “ dislodge/disturb” the sludge in your Septic Tank. The Sludge is at the bottom of the tank and covered with liquid. I’ve dumped at 2 different home Septic Systems for over 40 years and have never had any problems at all.
Thank you, RV Travel. This is certainly something that should be considered. We have a septic tank dedicated to the RV. It is located where we store our Rzv. We used it frequently when we were living in the RV for 8 months almost 8 years ago and infrequently now. In particular, this article has reminded me to add septic tank treatment more often; thank you! Have a great weekend and safe travels!