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RV Black Tank Advice from the “RV Proctologist”

| Updated Jul 27, 2022

One of the most common questions we get deals with the RV black tank and how to keep it clean and odor free. This week in Episode 406 of the RV Podcast, we interview a true expert – Steve Korsvall, aka “the RV Proctologist.”

For the past 15 years Steve has run his RV Proctologist business in Quartzsite, AZ, helping RVers with their black and grey tanks. 

Quartzsite is well known in RV circles. With an annual population of 3,700, Quartzsite grows during the winter months to a population of hundreds of thousand – with most of the new arrivals being RVers.

And when these visiting RVers experience problems with their black or grey tanks, Steve is there to help. He helps those in the RV parks and helps those boondocking in the BLM desert.

And boy, has he seen it all.

You can watch the full and unedited interview with Steve on our RV Lifestyle YouTube channel by clicking below:

If you'd like to just listen to the audio version of the RV Podcast, it's available on all your favorite podcast apps or by clicking the player below.


For those who prefer reading, here's an edited transcript of our interview with Steve Korsvall, “the RV Proctologist”:

The Most Common RV black tank problem – Not enough water

rv black tank
The black water tank is directly below the bathroom (gravity is your friend) behind the power step on the passenger side. The sheet metal box protects the macerator from road debris. The emergency dump port is the large plug at the center.

Mike Wendland:

Well, if anybody has seen their share of RV black tank issues, it is the RV proctologist, and because so many RV-ers spend so much time in Quartzsite, that's probably ground zero for black and gray tank problems. What's the most common problem that people have when they're trying to manage RV gray and black tanks?


RV Black Tank Advice from the "RV Proctologist" 1
Steve Korsvall, “the RV Protologist”

Most of the time… I'm going to tell you a quick little story right off the bat. It was a client that called us out of Salome out here. He had a brand new fifth wheel. He had less than a month, and I get out there and we start hydro jetting the RV black tank. So what happens is, we're out there, and all of a sudden, as we're hydro jetting, a whole container of chemicals comes out of the shoot, and we stopped it before it went into the system.

So we talked to the owner and said, “What in the heck is this chemical bottle doing in your RV black tank?” He says, “Well, when I bought this, the salesman never told me how to use the tank. So he told me, ‘Just throw the whole bottle into the tank.'” And so I said, “You got to be kidding me.” I said, “All right, let me ask what you did. Did you put any water in the tank?” “No. Nobody told me to put water in the tank.

So when you have a 40 gallon tank and it's a fifth wheel, you always have to start off with a minimum of five gallons of water in that tank. And what we recommend throw a cup of Dawn Dishwasher Soap down there. It's slippery. It makes the tank slippery.

But we took that out, and sure enough, the bottle had the lid on it and everything. And I'm going, “Wow, the rookies we have out there, they need to be taught how to use chemicals properly.” And that was just one of many over 15 years. It's happened at least three times to me, this situation.

Mike Wendland:

So I would think then that water in the RV black tank is the most important thing?


Exactly, exactly. And toy haulers go up to tanks like 75 gallons. Big tanks. So every time you go to a larger tank, you have to put more water in the tank, and that's what people forget to do.

When they pull up to a campsite, they plug everything in and they get all excited about life and camping, but they forget what to do underneath.

And sure enough, down the road over a week or two in camping, you don't have enough water in that RV black tank to break everything down. That's the biggest problem with it. People aren't using enough water when they're going number two, and especially on fifth wheels, underneath the fifth wheel, you drop down about a foot, then you go off at a 45-degree angle, and then it drops into a tank.

So that water's really got to push a long way sometimes in a fifth wheel.

What kind of toilet paper should be used in an RV?

toilet paper for rv black tank

Mike Wendland:

So here's another question that we get all the time from people: Do I have to use RV or Marine grade toilet paper or can I use regular toilet paper?


In our 40-foot RV, we happen to use Angel Soft. Angel Soft breaks down very easily.

Now, how you can test a toilet paper, take a leaf, take a Mason jar and throw it in a Mason jar for 24 hours, and then see if it breaks down. But in my 15 years of full-time RV-ing, we've never had a problem with Angel Soft. There are other brands out there with the lighter, but I recommend if you don't know what you're doing, use single ply for a while.

Never use wet wipes in a black tank. Never. Because they just wad up.

I had a little grandma with a big, beautiful quarter million dollar Class A. All she uses is wet wipes. The problem was, the whole tank clogged up and we literally had to take the plumbing apart. And I know our business gets gross once in a while, but you guys have to have a visual of this because we had to make a hook, like a big fishing hook, and reach in and just pull over two hours of wet wipes into a bucket and then re-plumb it.

If you're going to use wet wipes, put them in a trash can. That's just common sense.

Handling odor control in an RV black tank

Mike Wendland:

What do you do then for odor control and chemicals? There are so many different chemicals on the market that people talk about. What's your recommendation?


In the Quartzsite area, when it gets really hot, things start to cook in RVs. People are out here still over the summer and we get between 110 to maybe 126 degrees. So underneath the carriages, the RV black tank gets hot. We tell people to put more water in it.

If you keep dumping chemicals in there, it causes more of a stink.

So you want to put like five gallons in a 40 gallon tank. You need to put five to 10, five to 10 or even 15 gallons in that tank to start, because human waste doesn't fill up the tank too much.

Why proper venting is crucial for RV black tank problems


The best thing is water to keep odors down in the RV black tank. And make sure your vents are open, that are clear.

Mike Wendland:

Now when you say vents open, you mean on the roof? Up on the roof?


Yes. Yeah. Make sure those aren't covered up.

Now, when we pulled out some tanks, when people have their tanks fall out of their rigs, we have that. People drive down the road and their tanks fall out of the rigs. And they drag it underneath on the freeway and then they come to us. Now we've seen a lot of the newer rigs.

They call it wet venting. There's only one vent for the whole tank. Now that's kind of cheating, and manufacturers should know this, not to put one vent in a 40 to 60 gallon tank.

I've got a lot of proof on this, manufacturers putting only one vent, and that's called wet venting.

So you have solids coming down, but you also have waste going up the venting, through the top of the RV through the same vent. So the vent on a tank should be separate than the waste coming down from the RV.

Mike Wendland:

So how does an RV owner know whether they have that problem?


Yeah. They really don't until they have service done on a problem situation.

The ones that we're looking at, between 35 and $60,000 RVs are wet venting, are these fifth wheels.

Mike Wendland:

And there's no way to know this?

Empty the RV black tank before you travel

empty rv black tank


No way to know it until either we have to pull the tank down to fix a crack or fix something. We've done a lot of RVs that the tanks are a little bit narrower and the rails are just a little too wide. So that's when you get the vibration down the road. A lot of people make the mistake by leaving the products or the number two in the tank as they travel down the road.

They really need to clean their RV black tank out before they travel. Now put one or two gallons in your tank as you travel at the most.

We've had literally several RVs that they load up their tanks so much they drop right out of the bottom of the RV.

BONUS: How to Easily Find RV Dump Stations

More about RV black tank chemicals  – Don’t use pouches

Mike Wendland:

That brings up a couple more things about the chemicals, because the big complaint everybody has is odor after a while. Do the chemicals help with that? You mentioned putting a lot of water in, that's the best thing to do first. But what about chemicals?


Well, what we've seen over 15 years of cleaning out tanks, you use liquid or powder only. I hate to say this, don't be using pouches. A lot of people, what they'll do is they'll cut the pouches and dump it in into the tanks. That's great. If you got pouches, don't just throw it in and flush it down the toilet. You got to know it's breaking down.

We cleaned out a lot of tanks that they wad up like softballs in the bottom of the tanks, and then they clog up the shoot going out.

Mike Wendland:

I'm going to ask you about a brand name, it's the one I happen to use, so that's it. I have no connection with them, but I have used it over our 10 years, Happy Camper?


Happy Camper's great.

Mike Wendland:

I'll stay with that. But you do recommend some chemicals to help with that odor or not?


Don't overdo it on the chemicals, and definitely don't mix different chemicals. When you get frustrated that you got a clog, don't go down to the store and spend 40-50 dollars on chemicals. That is not going to be breaking down all the paper that's packed in there.

How to unclog an RV black tank

RV Black Tank Advice from the "RV Proctologist" 2


What you need to do is make sure you have more water in there. Now, let me recommend out there, if the proctologist isn't around and you need help, especially if you have a fifth wheel and it's clogged down on that 45 degree angle, go down to the hardware store. This is cheap.

Go down to the hardware store and get one of those thick core three quarter inch hoses, cut the brass piece off, hook it up to your faucet. And you got to get your gloves on, get some towels, put it around your toilet and get aggressive. And you just jam that hose down that shoot under your toilet and push it hard.

Mike Wendland:

And push it through.


Work it hard. Yeah. And push that paper down into the RV black tank.

So on chemicals, a lot of people don't use chemicals at all, they just use water, and they're very happy. And using the Dawn Dishwasher Soap.

I know a lot of RV parts stores don't like me saying that because they want the money and use the chemical thing. Most people who camp all the time, they got to empty their tanks about every 10 days. Seven to 10 days, people have to dump. So that liquid, which is like six to eight ounces in a 40 gallon tank, does only so much.

Mike and Jennifer's RV Lifestyle hat collection

RV Black Tank Advice from the "RV Proctologist" 3
Who needs a hat?

Who needs a hat? You do! Dad hats aren't just for dads. This comfy one's got a low profile with an adjustable strap and curved visor. Just the thing to wear on your next RV Lifestyle adventure.

Cleaning the RV black tank

Mike Wendland:

So there's a lot of things I've seen on newer RVs with this little connector where you can hook up a hose and it sprays out your black tank. Is that a good thing to get, Sani Flush I think they call it?


Absolutely. Yeah, that's a really good thing if you know how to use it.

You got to make sure that gate valve is open.

You have three different types of valves, maybe four, but mostly they're a standard gate valve, three inch black gate valve. You have your rod gate valve. That's usually, when you buy a new one, that's an aluminum rod that slides in there. It goes across underneath the belly. But over time it gets soft and bends and then you got problems. So you always got to make sure that's stout. And then you have cable valves and you have electric valves.

So it's very important to keep them open. Keep your gate valve open when your flusher is on. Now, most tanks, people don't know what a flusher looks like. They think there's a big sprinkler system in there. What it is, it's just as short like a two inch PVC pipe with a cap on it, with holes drilled in it. We've cut tanks open and that's what we see in there, until you get to the more expensive rates.

Mike Wendland:

And you call it a flusher, but it sprays the inside of the RV black tank, and supposedly loosens deposits and stuff?


It helps in the area that breaks up the stuff at the bottom of the tank. I would recommend if people would do this, if you're really concerned about your rig, at first this is what I think you should do, and I know the RV parts stores don't recommend it. Just about a minute or two, just leave it closed and run your flusher a little bit so it starts breaking up the stuff before it runs out. Run a little water in there first, and then kind of time it, a minute, a minute and a half, then open up your gate.

It will start to come out a lot better, a lot faster. You need to get the stuff out as soon as possible.

Pay attention when cleaning the black tank!


Let me tell you a little story what happened to a guy that I heard about? He was drinking a few beers, and what happened? Well, he went over to the other side, starting on this whole deal, he's drinking a few more waiting for things to happen. Well, his friend came over and he had just shut the black tank, but he forgot the flusher was on.

Well, his friend said, “Hey, let's go to the hardware store? I want to get this tool that I know about.” Well, he went to the hardware store. The problem is when his wife came home, about half an hour later, went to open the front door, there was a waterfall coming out the front door because he had shut the black tank and it all filled up the black tank, went out the top of the toilet onto the bathroom floor and out into the kitchen and downstairs.

So very important, when you're using a flusher, never walk away from that.

The problem with RV black tank sensors

Mike Wendland:

One of the biggest complaints every RVer has is that the gauge that shows how filled their RV black tank is, stops working. What can we do about that? And beside use more water. But it probably all goes back to that, I'm sure. But as I understand it, stuff sticks to those black tank sensors, and that's what causes that. Is there a fix for that, an easy fix that we can do?


There's different scenarios on that. People think they could use chemicals. I think what you need to do is, like I said, use the big rubber hose and wash that thing, run a water hose down there and flush it as much as possible. People say they could use chemicals. Really? I call them idiot lights.

As you get to know your rig, just open up the toilet flapper and look right down into the tank and see what's down there. A lot of times you can't, but you could time it. Let's say, you're starting camping on a Saturday, you have to just time it, seven to 10 days every time.

And you got to have kind of a little bit of a calendar to note. The sensors get gummed up, and when we do go in there, we jet them off so they're clean. We go with a high pressure jet and we jet those sensors off over time.

RV Fresh Water Tank advice

Mike Wendland:

Now I want to ask about the fresh water tank that people have. First of all, how long can they leave water in the fresh water tank? Say they've gone on a camping trip, they come back home, they put it in storage for a week or two. How often do you need to drain that fresh water tank when you're not using it?


East coast is different than west coast. You guys in the east coast have to figure about freezing and stuff like that. Now you're talking about basic summertime. You're fine with leaving it in for two weeks.

Mike Wendland:

Really? It doesn't get skunky in there in that tank?


I don't think so. You could put a little bit of white vinegar in there, that won't hurt anybody, and that'll help clean anything in there too. I could tell you another story about that if you'd like to hear it?

Mike Wendland:

Yes. I love the stories.


Okay. So we're out in Manteca, California.

This lady calls me and says, “You have to come out here and clean out our fresh water tank.” And I said, “Well, what's wrong with it?” She would not tell me. She was almost crying on the phone. So we get out there and the story is they were ready to go camping on a Friday, they had just bought this Class A, 30 foot Class A. Well, the husband had to go to work so the husband says, “Go down to the gas station and fill this up.”

It was a diesel unit. So he never told her where to put the water. Long story short, she just saw a spout there, she opened it up and stuck the diesel pump into the fresh water tank and didn't know. She actually didn't know and he didn't tell her. So it's very important for people to be on the same line. So she had pumped diesel into the fresh water tank.

I can't remember how many gallons of diesel into the fresh water tank, and they wanted us to go over there and clean all the diesel out of the fresh water tank.

And I said, “I'm sorry. I mean, I could jet it out as much as I can, but I would not drink anything out of it.”

I said, “You're going to have to replace the tank.” And so, that's that story. We've been to a lot of strange ones.

Mike Wendland:

How much fresh water should they have in the RV as they're driving?


It all depends on the run they're doing. If they're going 300 miles, put three to five gallons in there. Don't fill it all the way up to the top because wherever you're going, you can fill it up more.

Managing the RV grey tank

Mike Wendland:

What do we need to know about managing the RV grey tank?


Now that's a tricky situation because most of the lines going into a gray tank are only an inch and half. You got to have lines coming in from the sink, your vanity. I would recommend on all your sinks, get those stainless steel strainers.

The regular manufacturer gives you the regular strainer, get the ones that are very small for things to drain through on your kitchen sinks.

Keep your vegetables and all that stuff from going down the drain into the tank. In our area, because the water is so hard, what we recommend in this area when you're here, leave your gray tanks open all the time so you can get that stuff out of there. You got to keep it running, keep it flushing.

And then I know on the east coast there are a lot of people, what they do, they close it off and then fill it up so it all runs up.

But because of our hard water, the calcium in our water will not only lock itself into the bottom of the tank, but also vegetables and stuff will rot by sitting up against them. So it's very important if you're at a full hook up, open your gray tank. But make sure when you're ready to clean your black tank, close your gray tank and then open your black tank.

That's a big problem because a lot of plumbing on RVs, they have a combination pipe system underneath there. So if you leave your gray tank open and you open your black tank, the black stuff will run right into the gray tank, and then you got problems.

You want to close that gray tank before you open that black tank.

Mike Wendland:

I'd always heard that we should always fill up the gray tank and then when you empty the RV black tank, then empty the gray so the gray will help wash out some of the residue. And you're saying, leave it open when you're in a full hook up, but before you dump, close it, get some water in the gray to still do that?


You could use Happy Camper in your gray tank too.

If you're going to close your gray tank, run some hot water in there, and throw some Happy Camper down there.

Same thing with the other liquids or powders. You could do that in your gray tank, but then go ahead and open up that gray and get it flushed out.

RV grey tank “breathers” and slow flowing water


One more thing about your gray tank.

Under your sink, under double sinks in the kitchen, they call them a little breather under there.

There's a little cap under sinks on both the vanity and the kitchen. It lets air into the pipe so things drain out easier. It has to have air. Just like a house, most pipes that are underneath the floor have a vent that goes to the roof that gives air to the pipes so things are able to flow. So what happens on an RV, like on a double sink, there's two P traps that go up, and then there's… It's called a dirty arm. A dirty arm goes over and comes up and it goes to a cap that's right at the flood level of the sink.

It unscrews by hand. If it's tight, you stick a screwdriver through there and break it loose.

Anybody can do it. Just look under your sink. If you've had a rig for several years, take it, unscrew that, run it under hot and soapy water and wash it off, and then screw it back on. You don't have to wrench it on hard, just hand tight.

So if people are having problems with slow flowing water out of their sinks, most of the time, it's that breather not getting enough air to those pipes.

Keep the RV black tank valve closed at the campsite until it is time to empty

Mike Wendland:

Last question for you. So many times I go to an RV park and I see people who have their stinky slinky from the RV black tank in the dump, they have it in the dump, and they have the black tank open, and they're kind of just passing it right through there directly from the toilet. A good idea or a bad idea?


Bad idea.

What happens most of the time when people do that, it pyramids right back up into the throat of the toilet and then people wonder why they're getting clogged up.

Mike Wendland:

So you can leave the gray one open, which is good if you're taking showers, it's going through, but never leave the RV black tank open until it's time to dump?


Exactly. Exactly.

Mike Wendland:

We're going to have to have you back and I know we're going to get lots of comments and lots of questions on this, Steve.

A Final story from the RV Proctologist

Can I tell you one other funny story?

So we're at a gas station several years ago and all of a sudden this lady comes out with her camera. Because we have RV proctologist on the side of our trucks, and then we have RV colonoscopies on the very back as well.

I told my son, because we're a father/son team, and so I said, “Give her a brochure.” And what happened was, “Oh, you don't need to give me a brochure. Do you know you were in the LA Times newspaper last Sunday?” I said, “No, we don't know about that.”

And she says, “Well, you had the hundred year centennial drive through Arizona, and it said that when you come through Parker and you're heading for Quartzsite, they said, ‘Well, you know you're in RV heaven when you see the sign for the RV proctologist.'”

I want to tell you one other story. So a nurse calls us, and said, “I used to work for a proctologist in the hospital and we called him the Rear Admiral. So, because he retired, I'm going to call you the Rear Admiral.” But she said that when she was driving around a corner there in Yuma, she saw a sign for us there.

She was driving a Class A, she was drinking a cup of coffee, she had never seen our signs before, and she was coming around a corner… And she said, “I was drinking the coffee. My dog was sitting up on the dashboard.” She said, “All of a sudden I started laughing because I saw your sign and I spewed all over my dog, all over the dashboard with coffee, and I almost ran off the side of the road because I was laughing so hard. I've never seen a sign for the RV proctologist.” So that's one of many, many stories that we have that we run into. They're very hilarious.

Mike Wendland:

And Steve, you are a wealth of information, and we thank you so much for being on the podcast.


You're so welcome. You're so welcome.

Where are you RVing next? Did you learn how to take care of your black tank?

Let us know in the comments. We'd love to hear your stories too.

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RV Black Tank Advice from the "RV Proctologist" 5

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RV Black Tank Advice from the "RV Proctologist" 6

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Mike Wendland

Published on 2022-07-27

Mike Wendland is a multiple Emmy-award-winning Journalist, Podcaster, YouTuber, and Blogger, who has traveled with his wife, Jennifer, all over North America in an RV, sharing adventures and reviewing RV, Camping, Outdoor, Travel and Tech Gear for the past 12 years. They are leading industry experts in RV living and have written 18 travel books.

4 Responses to “RV Black Tank Advice from the “RV Proctologist””

July 27, 2022at12:58 pm, Robert Shather said:

Hi Mike ,
I’m new to the RV lifestyle. Was wondering when storing my RV for a few weeks in between outings should I leave my black tank empty ( clean ) or full with clean treated water?
Robert Shather


July 29, 2022at1:31 pm, Team RV Lifestyle said:

Hi Robert – That would be a good question for mike to answer on their podcast. (They answer questions each week) – you could send the question to – or feel free to ask it on your facebookgroup at – Happy Trails! Team RV Lifestyle


July 27, 2022at11:40 am, Janice Porter said:

This was one of your best, most informative and authoritative interviews yet. Thank you.


July 27, 2022at12:05 pm, Team RV Lifestyle said:

Thank you so much for the encouraging feedback- we appreciate it! Team RV Lifestyle


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