Friday, March 24, 2023


Dump your holding tanks in your home septic system?

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

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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1 month ago

If your home is rural enough to have a septic system, why not use your gray tank to water your plants and/or grass?

1 month ago

My bathtub holds more water than my holding tanks… Dump away!

Dave A
1 month ago

Been dumping in the septic tank for 31 years no problem.

1 month ago

I have been using Rid-X in my septic system since day 1 of building it for 40+ years. After 30+\- years our local township now mandates pumping the holding tank every 3 years. The first time we did it we paid to have the leach field scoped. According to the honey dipper he said that the leach field looked great and no issues detected he also recommended we continue with Rid-X. My neighbor used some other snake oil and had issues after the 25 years in his built new house. Rid-X in the house and holding tanks after every dump.

tommy james
1 month ago

You have a point but now I wonder if the same thing happens when I empty a bath tub or a hot tub ? That is in many case is as much volume or more then my 30 gallon rv tanks. But then again I only have #1 and #2 and NOTHING else goes into my RV tanks. The toilet paper is placed in a small paper bag and put in the garbage or camp fire.

1 month ago
Reply to  tommy james

The bathtub comment is valid by volume, although keep in mind the bathtub skimmer drains slower than some people dump their RV through a 4″ hose. The problem is turbulence in the septic tank, not volume here… the leach field should be able to handle a bathtub of water as long as it’s not carrying solids with it.

Now, dumping the hottub down your septic? DON’T do that. Many tubs are 4-600 gallons for larger ones, several hundred for smaller ones. If you trickle that down your drain, maybe you get away with it but if you’re surging all that water suddenly into your tank, it probably displaces the airspace and DRIVES the solids into your field. For my tub, it’s really not hard at all to run the hose onto the lawn and skip the septic completely…

Chris Zimmerer
1 month ago

Plumber told me not to use rid-x. Use packets of yeast

1 month ago
Reply to  Chris Zimmerer

Only use yeast if your baking bread in your septic tank. Here’s a real answer from a real plumber. When you drop a deuce and flush it there are millions of bacteria from your gut that go into your septic tank joining billions more that are breaking down the waste in the septic tank. The bacteria are reproducing on there own in the tank as long as there food (your waste) keeps coming in. I have been dumping my black and grey tanks in my septic tank for over 35 years with no ill effects, dumping it all at the same time. As far as the clogging up the leech field here’s the rules on maintaining your tank so that can’t happen. With a family of 5 the tank on BOTH sides needs to be pumped every 5 years. The only time you can clog the leech fields is if you never have it pumped for 20 to 50 years (seen this happen out of sight, out of mind). The only thing I saw that was right is DON’T use formaldehyde base treatments. I’ve use Roebic brand RV and Holding tank treatment which is bacteria based

1 month ago
Reply to  Crowman

Roebic. Check it out. I have switched from Rid-x to Roebic. Research on the net if you wish. They have a number of products for different situations. I have not had problems with Roebic – it cleared up some problems. ACE, for one, carries it, or on the Net of course. My septic system has never been happier. I asked it. It did not gurgle back. That is a happy septic system. My RV does not have real large tanks, but dumping them into my septic system has never been a problem. I have lived on septic systems for well over 50 years. I do take care of the system as replacement is tens of thousands of dollars.

1 month ago
Reply to  KellyR

Because I dump into my septic, I NEVER use “odor control” stuff in the RV — and truthfully, you never need to unless there’s a problem with negative RV airflow.

I have heard that using the regular bacterial treatments (meant for helping your home field) in the RV as well helps with those who do have odors… can’t say if it helps, but I don’t see how it could hurt anything to get a jump start breaking it down.

1 month ago
Reply to  Wolfe

Wolfe, I don’t use treatments in my holding tanks either, they are not septic systems but HOLDING tanks. I like your idea of using septic systems products in the holding tanks as they would readily treat the septic system when you dump. I think I will try it. It makes sense.

1 month ago

First I added 3, 8 foot diffusers that could handle about a 100 gallons of liquid at the time, in the back yard…
My TT has seperate valves for gray water and black. And we only dump the gray in the new drain field. Then the black water is only dumped once a week into the sewer system. And never add harsh chemicals. We have a Y that is replaced we go on the road.

Jesse Crouse
1 month ago

We use a “Bio-Method” for our RV and have NO odor or clog problems for over 3 years. Never use products having formaldehyde or the like on a septic system. From a Plumber.

1 month ago

My daughter and family recently moved into a house that has a 30 amp hook up for our rv and a hookup to dump our tanks outside their house. They use Rid-X for their septic system. What do you suggest we use after we dump our tanks?

Carl W
1 month ago

Interesting concerns. However, I do know that some State Parks in my home State have dump stations that are NOT connected to sewer mains and the treatment method is via oversized septic treatment.

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