Thursday, October 6, 2022


Are you managing your RV tanks? Part 1

By Jim Twamley

I’d like to address an important issue – tank management. Most RV’s have several tanks: fresh water, gray water, black water, hot water, propane and (for motorhomes) fuel tanks. Let’s deal with each one separately:

Fresh water tank

Several times I’ve been at RV parks when the main water supply was temporarily shut down. After the second time of being caught with little or no water in my fresh water tank, I began making sure my fresh water was topped-off once I was at my destination park. It’s always a good idea to keep it full, especially if you are staying a few days. When traveling I usually have it about half-full unless I know I am going to be staying overnight in Walmart or another dry-camp situation.

We are close to our weight limit, so I empty all the waste tanks (except for a few gallons in the black tank) prior to our hitting the road.

Black tank

This is the human waste tank. I don’t use chemicals in my system because the natural enzymes sufficiently break down the waste. I frequently clean out the tank with fresh water. Never had a problem, no odors, no funny chemical smell. I keep a few gallons of fresh water in the black tank after I wash it out to cover the waste. If it’s able to be covered by water, the enzymes do their job and odor is kept to a minimum.

If your gauges aren’t working properly it’s often because toilet paper is hung up on the sensors. To remedy this put about 10 pounds of ice and 5 to 10 gallons of water in the tank and drive. The sloshing motion of the floating ice should help clean the sensor. We do not put tissues into the black tank nor do we put in toilet paper that was used for other things other than its primary purpose. This reduces the prospects of clogging.

Our rig is equipped with an external hose connector that flushes the tank. I use a clear elbow fitting that attaches to the sewer hose so I can see when the tank is clean and running clear water. With the clean water still running into the tank flush out, I close the main valve and allow about 10 gallons of water to accumulate in the tank, then open it up again. This flushes out any excess toilet paper and waste. I then fill it with another 5 gallons of water and close the valve. Following these procedures will give you trouble free service of your black tank.

When camping for extended periods where access to a sewer is not available (like at a relative’s house) you can purchase a macerator which attaches to the sewer hose fitting and grinds the waste and sends it through a regular garden hose to a dump site like a cleanout, toilet, washer/dryer drain or outhouse. These run off of 12 volts and have a manual switch. Here’s one at for less than $100. You’ll need to put together the fittings to adapt it to your RV water outlet.

We’ll have the rest of Jim’s suggestions on RV tank management next week. 



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2 years ago

I completely drain and flush our black & gray tanks before winter storage. When Spring arrives I add ample scoops of Rid-X and then fill the black tank to 3/4 and let it sit until our first trip (ideally I like to let it sit for 3 to 4 weeks). We drive to our first destination before dumping the black tank to hopefully slosh the mixture. Then after dumping I put enough water to cover the bottom of the tank. When first using the toilet we use a lot of water when flushing and use less during flushing after the first day. This ensures that nothing “sticks” to the bottom of the tank. Been doing this for 20 yrs and have never had problems with smell or faulty sensors. In my opinion the best thing to ever happen to tank sensors is Winnebago’s sensors that don’t protude into the tank. Maybe other manufacturers use similar sensors but if they don’t they should.

Paul S Goldberg
2 years ago

We have a macerator system I installed many years ago. On Friday I close the gray drain to collect wash water and shower water. On Saturday I open the black and run the macerator until the tank is empty. I turn off the macerator and leaving the black open I open the gray to let that water into the black tank to flush it. I often will do that twice. I close the black tank before it can completely drain and pump out the gray and leave it open (If camping in one place) until the following Friday. We have been at this long enough that it is a rhythm that does not require monitoring the gauges, unless we have company staying on board.
Fresh water is always kept close to full, you just never know – we are in a diesel pusher with enough excess GVWR not to worry about 800 pounds of water.

Jeff Kwiat
2 years ago

One thing I have done and seems to work on scrubbing the black tank is a Little Rock salt with the ice and water
Having a black water tank flush hose coupling helps as well

Keira B
2 years ago

The author is obviously new to RVs. Live full time in an RV for 10 years, and then write an article about tanks.

Tim B
2 years ago
Reply to  Keira B

Can you enlighten us with your constructive RV tank experience please?

2 years ago

I have a sani-flush system to clean out the tank after dumping. I’m not sure i can close the tank valve and just keep adding water as the pressure will cause a problem. so how does this person add water to the tank? i can do it through the toilet, but it doesn’t sound like this is what he is doing?

2 years ago
Reply to  arlene

Run the sani-flush with the valve closed. BUT, we just do it for about 3-5 minutes IF the valve is closed. We have a large tank so if yours is small, adjust the time. This is probably overkill, but when we open valve back up, I dump several pots and pitchers of water into the toilet. We have noticed this really helps as we can see the results through the clear hose attachment. After valve is closed, we then add about 3-4 gallons of water through the toilet with a scoop of Happy Camper. If we suspect a clog, I have added the water along with a cup or two of Pine Sol. Then drive. It really helps.

Dave Kaiser
2 years ago
Reply to  arlene

We too have the sani-flush system but hasn’t worked for a long time. Any suggestions on how to bring it back to life? Are using the wand down the toilet to flush out.

John Wegner
2 years ago

Please post your diet plan because I want to have those enzymes that keep your poop from stinking!

2 years ago
Reply to  John Wegner

I really didn’t understand this part. Is the author putting some kind of enzyme in the tank and not calling it “chemicals”?

2 years ago
Reply to  Heather

Didn’t quite get that either.

2 years ago
Reply to  Heather

Your body has natural enzymes that are present in the waste solids &, if not killed by the artificial chemicals some people add to the tank, the enzymes will break down the solids, if given enough time. It’s no different than a septic system for a home in the country. Your septic system holds the waste solids & slowly breaks down the solids, which then drain out into the drain tiles beyond the septic tanks. The key with your black tank is to not put any cleaning or other chemicals into the black tank that will kill the enzymes & prevent them from doing their thing.

2 years ago

I have an additional tank, in addition to these: as I decided to heat bath water using the heat of the sun, I installed a small water tank (only 50 liters) in a small tower that rises when parked – this saves me a lot of energy

2 years ago

A few years ago a guy did an experiment to see if ice cleans the black tank. Was very thorough, driving around, careful measurements, etc.
It does not work.

Bob p
2 years ago
Reply to  Michael

Yep the ice just floats and doesn’t break anything loose, you’d probably have to put 40-50 lbs of ice to get it to scrape anything loose and on a hot day it wouldn’t last a half hour. Since most ice you buy doesn’t have sharp edges it won’t scour anything.

2 years ago
Reply to  Michael

Interesting video. He has several RV related videos.