Using A House’s Sewer Clean-Out for RV Dumping

 Using A House’s Sewer Clean-Out for RV Dumping

Here it is – my sister’s septic clean-out, behind the rhododendron bush and among the shrimp plants. In the south, this is all white PVC pipe. the square on the top is used to unscrew the four inch cap.

First off, I don’t even HAVE a house, so this is for those of you who still have sticks and brick attachments, or are visiting folks who do. Houses have connections that come in handy for us RVers staying at a residence, and I’m not talking about the electricity and water. I’m talking about sewer connections you can dump your waste water tanks into.

City sewer connections have what’s called a clean-out, which is a large opening into the sewer line just as it leaves the house and heads toward the city sewer connection. It’s perfect for dumping your gray and black water tank contents if you don’t want to drive across town and give people money, which is usually what you have to do when dumping in a populated area. The trick, however, is to find this clean-out, because few homeowners know where they are.

In houses with connections to a municipal sewage treatment system, the sewer line comes out from under the house and usually makes a bee-line for the street where the sewer lines are. If you’re in the middle of the block this is easy – corner lots could go either way.  Water meters are another utility usually on the side of the lot where the sewer hookup is, so that will help give you a clue to location.

Here it is - my sister's septic clean-out, behind the rhododendron bush and among the shrimp plants. In the south, this is all white PVC pipe. the square on the top is used to unscrew the four inch cap.
Here it is – my sister’s septic clean-out, behind the rhododendron bush and among the shrimp plants. In the south, this is all white PVC pipe. the square on the top is used to unscrew the four inch cap.

Get a little shovel and gently poke around in the flowerbeds and other stuff along the base of the house’s foundation. The line is usually just below ground level, and is a 4 inch PVC pipe (probably cast iron up north where the ground freezes – one of you Yankees help me out here). It’s the only huge pipe coming out from underneath the house – supply lines are much smaller. There will be a four inch white plastic screw-in cap with a square protrusion in the middle.  Once you have found it, clear enough dirt so none goes down into the pipe when you open it, and get a big wrench or pliers and unscrew the cap.  Pull your RV up so that your emptying hose will reach the clean-out, and dump away to your heart’s content.   Replace the cap and the dirt, remove any evidence of trampled flowers before the homeowner sees them, and you’re done.

I have heard of, but never encountered, municipalities where this is illegal – check local ordinances before you do this. There’s also a huge difference between city sewers and septic systems. For one thing, with a septic system, the clean-out is going out the back of the house to the septic tank and drainfield, not out the front to the street.

Secondly, septic systems can’t handle giant loads of water, so 30 gallons from a Roadtrek or Class B RV should be no problem, but make sure they aren’t all taking showers and washing clothes inside when you do it.

Thirdly, make sure you use the clean-out upstream from the septic tank, as close to the house as possible. If you dump into the septic tank itself, do it upstream of the baffle. Dump into the drainfield and you’ll probably be invited to stick around for the dig-up-the-drainfield party – as the guest of honor. You don’t want this distinction.

When in doubt, drive across town and use the RV dump.





"campskunk" is a blissfully retired former public servant who has left the challenges of how to run the government to younger and less cynical hands, and wanders the continent in his Roadtrek Class B RV with his wife and cat. In addition to his work in the public sector, he has also at various times been a mechanic and delivery driver, skills which come in handy in his new role. Because his former job involved the forensic evaluation and sometimes the subsequent detention of some not-so-nice people, he uses the name campskunk instead of his legal name on the Internet. His was not the type of job where customer service feedback would be welcome.


  • Great information! We’re set up at our place for this and it is so much easier than using a dump station…especially when there is a long line up. Thanks again for sharing your knowledge.

  • I’m one of those “Yankees”-never seen a cleanout on the outside of the house. The ones I see are always inside the house usually in a closet, basement, or crawlspace. Don’t want to be dragging hose through the house!

  • I agree with Brad13. This is a great idea in some parts of the country and would work when visiting at my son’s place in California, where the clean out access is next to the house in the front yard. However, at my house in upstate New York, the sewer line clean out is inside under the basement stairs.

    • thanks, dan and brad – i had the feeling things were different up North. most of the houses here are on concrete slabs. due to the high water table here, we don’t call those “basements” – we call them “wells” ­čśë

  • One correction, Mike. Some houses do have their septic systems in the front yard, as does ours. We just had the entire system replaced, including the drain field, and it’s still a mess, but at least they did put in a clean out, where we can reach it from the driveway with about twenty feet of hose. Also, the screw-in elbows available for most RV hoses will screw right into the clean out, which might save an overflow mess. As always, have a water hose handy to rinse out the hose and fittings when done.

  • Good advice Campskunk! We have two clean-outs. One is next to the house and other is in the side yard about halfway out to the street. We dump the tanks into the clean-out after arriving home after every trip. The sewer line is located on the opposite side of the house from the driveway. I’m sure the neighbors wonder what the RS Adventurous is doing in the middle of the yard on the “wrong” side of the house when we are doing this task. We also have a place there to hook up a water hose which we use to flush out the tanks. Works great!

  • I think you should add a caution here about septic tanks. In order to work properly they need bacteria to break down sewage. If you use chemicals in your tank you could kill the bacteria and cause problems for the owner of the tank!!! I think this is an extremely important caution to mention and to correct in article. If the bacteria dies you have to have tank pumped and start over again and helps to add bacteria product monthly.

    • good point. the formaldehyde based little bottles are not compatiblble with septic tanks. I bought these once, used one, and threw the rest away. they smell terrible.

  • I have a cleanout outside a kitchen window and also outside a clothes washing machine room. Can I just connect to these outlets near my RV? What keeps the waste from going back up into the kitchen sink or the washing machine? Also the diameter size of the drain hose is different than the size of the pipe extending outside the house.

    Would appreciate any help. Thanks.

    • Larry, a clean out is huge-4 inches across or so. your three inch flexible hose from the RV should fit. if it’s smaller than 4 inches, it’s not a sewer clean out. Gravity prevents it from going back into your house; sewer lines slope gradually downhill throughout their length.

  • Great info- Thanks ­čÖé

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