Using a house sewer for RV Dumping

 Using a house sewer for RV Dumping

Visiting family but need to empty your RV black tank? It is possible to use a house's sewer clean-out for dumping. Here is how.

Remember that scene in the Christmas Vacation movie where Cousin Eddie emptied the black tanks of his Class A wreck of an RV into the city sewer outside Clark Griswald's house?

Well, it's possible. Sort of. But not at the curb down a sewer grate where cousin Eddie did the RV dumping but in what's known as a sewer clean-out that most houses have.

Fulltime RVer Campskunk wrote about doing just that a few years ago. Here's an update to that post.

How to empty your RV black tank in a house sewer clean out

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.

Finding the house sewer clean out

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.

By the way, for you vans of the movie… here is a YouTube clip of that iconic Cousin Eddie scene:

It could be illegal to do RV dumping like this – Check local laws

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.

Using a House sewer connection for RV dumping has limitations

Secondly, septic systems can't handle giant loads of water, so 30 gallons from a smaller Class B or Class C 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.

RV Lifestyle

14 Comments

  • 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” 😉

  • 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 🙂

  • Up north there should be an outside CO every 100′ of sewer service lead. If you are less than 100′ from the sewer connection you probably will not have a CO. I do have a CO in the yard and I added a bayonet connector to the top and enclosed it in a sprinkler valve service box. If there is a line at the cg dump sta I just drive home, pull up to the CO, connect both ends of the hose to bayonets and dump. No chance of spill with a bayonet on both ends of the hose.

  • The building code in effect when the house was constructed will determine if you have exterior clean outs and how far apart they my be placed. My home does not have any clean outs on the exterior of the home. It was built in 1969. I believe most building codes. Required them by the mid 80s.
    If you don’t have clean outs, call your municipality and see if you can dump for free or a reduced rate at their location. I found this in Maine. $25 dump fee unless you had a city address, then it was free.

  • Thanks for the post. Question: I have 2 clean-out valves in my front lawn (bushes) only a few feet apart. Would I dump into the one closest or furthest from the house?

    Thanks,
    Gregg

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