Leave Black Tank Drain Valve Open When Flushing!

[Rivernerd]

This post is offered in the hope it will help someone else avoid my dumb mistake. 

It has been my practice to flush the black tank after dumping using the black tank flush inlet port below the bathroom window.  I carry a separate black-colored hose just for this purpose.  In the past, I have always left the black tank drain valve open when flushing.  At the conclusion of our most recent camping trip, after a first flush with the drain valve open, it occurred to me that I might get a more complete flush if I mostly filled the black tank with clean water through the flush port first (which required that I close the black tank drain valve) then let gravity force the contents of the mostly full tank out the drain.  To avoid overflowing the black tank, I carefully watched the Seelevel monitor, then ran outside to turn off the hose bib when the Seelevel black tank monitor hit 90%.  I then opened the black tank drain valve to drain the black tank contents.

Out of an abundance of caution, I decided to verify that this process had caused no overflow from the black tank.  I removed the access cover from the front dinette seat so I could see the aft part of the black tank.  Good thing I checked!  When I saw a few tablespoons of water in the bottom of the trailer just aft of the black tank, I realized that our Seelevel monitor is not 100% accurate, and that even though I turned off the hose bib when it read 90%, the black tank was actually full of water!  Fortunately, the overflow was limited to a few tablespoons, which were quickly mopped up.  When I got home, I sprayed that area, twice, with Lysol disinfectant spray, in case that bit of water leakage was contaminated.

The moral of the story:  when flushing the black tank, always leave the drain valve open.  Fortunately, my momentary lapse of judgment (it seemed like a good idea at the time...) occurred after a complete drain, then a first flush with the drain valve open.  So, the minimal overflow should have been mostly clean water, which was easily dealt with.

I expect it would never occur to most people to leave the black tank drain valve closed to mostly fill the black tank when flushing, just to get a more complete cleaning.  But if any of you folks, like me, ever think of trying that method:  don't!  It's not worth the risk of an overflow.

[topgun2]

The problem you encountered is one of the reasons that some people use one of THESE versus trying to use the SeeLevel system.

One of these flow monitors also reduces the need for running back and forth from outside to inside and back again.

Glad the "overflow" wasn't too bad for you.

Bill

[Geronimo John]

3 hours ago, Rivernerd said:

The moral of the story:  when flushing the black tank, always leave the drain valve open. 

Your initial reason for closing the black tank drain valve is a good one.  Your down fall was relying on the electronic gauges.  

My process is to stand on the toilet tank flush valve and to observe the water level in the black tank while flushing.  The advantage of my 2018 OE2 is that it has a manual water shut off valve just a few feet from the toilet (Under the front dinette seat).  This allows me to slow down the fill rate as the level in the black tank approaches full.  Then when nearly full, I turn off the water flow at our valve. 

Sadly, OTT decided to not install said shut off valve on newer models.

GJ  

[Steph and Dud B]

Lots and lots of RVers do what you did - close the valve to put some water in the tank with the rinser. I do. Many have reported similar, and worse (much worse), results. Glad you didn't create a rooftop fountain or toilet gusher as others have.

[Mike and Carol]

We’ve done the closed valve rinse for years.  There’s no reason to fill to 90%, or even 70 or 80%.  When Carol tells me we’re at 50 or 60% I open the valve.  Do that twice and you’re good.  Mike

[John Welte]

9 hours ago, topgun2 said:

The problem you encountered is one of the reasons that some people use one of THESE versus trying to use the SeeLevel system.

One of these flow monitors also reduces the need for running back and forth from outside to inside and back again.

Glad the "overflow" wasn't too bad for you.

Bill

Bill,

Looks very useful.  I was rinsing the black tank and was inside watching the % full on the black tank.  It stopped registering at 55%.  I thought, well maybe it will jump up to 75%.  I kept waiting.  Then I saw the toilet bowl valve move. I ran outside to turn it off.  That flow monitor looks very useful.  Do they work as intended?

John

[mossemi]

20 minutes ago, John Welte said:

Do they work as intended?

I will add to Bill's post about the Orbit flow meter, mine works pretty good, but I only use it when camping solo.  

I always flush the black tank when we are leaving a site equipped with a sewer connection and like Mike and Carol, we use the SeeLevel to a 50-60% fill and then flush.  We may do a black tank flush at the dump leaving the campground, but only if there isn’t anyone waiting.  If I start rushing things because people are waiting and 👀, it often ends badly.  
I always thought that a 50% flush after the main flush was only beneficial in cleaning the black drain pipe.  
One last comment, I try to stick with the method I have been using to setup, breakdown, sterilize or anything concerning the Ollie, it helps prevent mistakes on my part.  If I think there may be a better way, I make a note and then mull it over a while before putting into practice.  If I break away from any of my normal routine, I usually end up making a mistake.

Happy camping,

Mossey

 

 

[jd1923]

1 hour ago, Mike and Carol said:

We’ve done the closed valve rinse for years.  There’s no reason to fill to 90%, or even 70 or 80%.  When Carol tells me we’re at 50 or 60% I open the valve.  Do that twice and you’re good.  Mike

Totally agree with Mike, though there is an easier method...

Usually, Chris is doing her stuff and I only ask for help on a job, when I cannot do it myself. The mechanics motto!

Normally, I just go with my gut feeling, on how much water would half fill the black tank. But if you were the more cautious type, you could time filling a one-gallon jug of water, given you're using an unknown water source (PSI and GPM).

Then determine your black tank capacity, divide that number by 2 for 50% full, and run the hose for that amount of time. If you go less or longer NBD since you are only targeting 50%. I do this 2-3 times, until the drain water looks clear and clean. No way you want to come anywhere near full. The cr@p and TP is in the bottom 10-20% of the tank, given you empty regularly. Best wishes and keep the brown stuff downstream! 🤣

[HDRider]

12 hours ago, Mike and Carol said:

We’ve done the closed valve rinse for years.  There’s no reason to fill to 90%, or even 70 or 80%.  When Carol tells me we’re at 50 or 60% I open the valve.  Do that twice and you’re good.  Mike

That is how we do it.

 

Then we add a little Calgon and Pine-Sol to the toilet and flush a couple of times to let that work on the tank using the bumpy road travel to loosen anything and everything.  I have found the roads around Lafayette Louisiana very good for this process.  🤣

[Townesw]

I stand outside beside the trailer while filling the black tank through the flush valve. You can hear the water spraying inside the black tank. When I hear the water level in the black tank rise above the flush valve I leave the water running and just pull the black tank dump valve. I do this 2,3,4 times or as many times as it takes until I see clear water and no floaters in a clear fitting at the terminal end of the sewer hose. Only then do I turn off and disconnect the flush hose. Never had a problem doing it this way. 
 

Sometimes I delay pulling the dump valve a little just to make my wife hollar at me “Ok OK OK DUMP DUMP DUMP!!”

[topgun2]

12 hours ago, John Welte said:

Do they work as intended?

I've never heard of any problems with them.

However, its been awhile since I've actually had one myself.

Bill

[Steph and Dud B]

Completely unscientific but I've done it for years: fill tank with flusher for 45 seconds, pull valve and rinse for 30, repeat for 3 cycles.

[SeaDawg]

26 minutes ago, Steph and Dud B said:

Completely unscientific but I've done it for years: fill tank with flusher for 45 seconds, pull valve and rinse for 30, repeat for 3 cycles.

Just make sure you time it!

🤣🤷🤣

[Ronbrink]

On 10/24/2023 at 8:16 PM, John Welte said:

That flow monitor looks very useful.  Do they work as intended?

To topgun2’s point, I make use of a digital water flow meter connected directly to the dump station’s water spigot, next a hose valve to control flow, then a dedicated 25’ Zero-G hose with a quick disconnect to the black tank rinse-out port inlet. This assembly is rolled up and stowed within the rear bumper compartment when not in use. Prior to dumping the black tank, I setup this rinse hose assembly; the dump station hose is removed from the spigot regardless of condition. Once the black tank is initially dumped, the black tank valve is closed. I then zero out the meter, open the hose valve, then measure 10-12 gallons before dumping the rinse water; the hose valve remains open during this rinse dump process. When complete, the black tank dump valve is again closed, the meter is zeroed out and water allowed to fill to the measured amount. This rinse cycle is repeated up to three times. The use of the meter does not require having to go in and out of the OTT to monitor the tank level, which is not accurate, especially with the tongue raised to better hasten the dump.

[RustyMD]

We once had an organic obstruction to our black tank, AKA a plugged toilet. I used the black tank flush valve to clean it from down below (black tank drain valve closed). When I flushed the toilet there was an air pressure explosion of the obstructing material over pretty much the entire bathroom. Oh my! We spent a while cleaning the mess.

Two conclusions: #1-know that it’s a straight shot to the black tank from the toilet. Just take a stick and push the obstruction into the black tank  #2-do not flush the black tank with the drain valve closed without being keenly aware of the pressure you are creating in the tank and its associated connections. (I will NEVER flush the black tank with the drain valve closed 🤠.

[Geronimo John]

On 10/25/2023 at 2:29 AM, HDRider said:

Then we add a little Calgon and Pine-Sol to the toilet and flush a couple of times to let that work on the tank using the bumpy road travel to loosen anything and everything.

The tip for using dishwasher pod(s) in the black/gray tanks has been around for some time.  When I want a really clean black or gray tank, I'll add a pod to the grey tank, and two pods to the black tank. Using "Calgon" brand is not required.  I buy the cheapest I can find for this use.  As you suggested, a few miles down the road for it to slosh around and break down the solids greatly reduces the time flushing the tanks. This is especially useful at the end of the season.

On 10/25/2023 at 2:45 AM, Townesw said:

I stand outside beside the trailer while filling the black tank through the flush valve. You can hear the water spraying inside the black tank. When I hear the water level in the black tank rise above the flush valve I leave the water running and just pull the black tank dump valve. I do this 2,3,4 times or as many times as it takes until I see clear water and no floaters in a clear fitting at the terminal end of the sewer hose.

As somewhat of a minimalist on what I carry, strive to minimize using extra hoses, valves, flow meters.  As such, your approach has merit IMHO.  Especially for those without a black tank flush water flow valve, you approach makes a lot of good sense. 

That said, I would suggest a few cautions for learning the sound change:

A.  The sound of a flooded black tank nozzle may vary with the pressure/flow of the water source feeding it.  So experiment with the hose bibb valve to recognize this.

B.  When learning the sound, get a helper inside with a flashlight to observe the black tank water level. Have them open a window or use you cell phones to facilitate communication.  Then have them shut off the ball valve flowing water to the flush valve, and stand on the flush valve foot peddle. Their job is to advise you of the progress of filling the black tank. 

C.  Before starting, make sure that all items on the bathroom floors (I.E. the lower one with the floor drain, and the higher one where the toilet tank sits) are removed from the area.  One of my worst mistakes was having my dirty cloths hamper on the lower floor and flooding the area from gray tank goo.  😞  Cleaning a soiled bathroom floor is easy vs. dealing with 25 pounds of really really bad smelling wet cloths.  While boondocking 40 miles from any laundry or water sources. 

GJ

[jd1923]

I just started using the Pine-Sol/Calgon solution that @HDRider suggested. I learned this from the Kleen tank guy: Kleen Tank, the nationally-recognized, independent RV tank cleaning service

Not enough experience with it yet, but the idea is the Pine-Sol keeps tank surfaces clean and the Calgon Beads will keep tank bottoms and drainpipes slippery and lubricate the valves. Not just used for occasional cleaning. These are flush tanks and NOT septic tanks. Given this works, the idea is to have this in your tanks only and stay away from other cleaners and septic tank additives (which I never use, even in 3 homes where we've had with septic systems).

Since having this in the Black and Gray tanks, I have not once smelled the strong smell of Pine-Sol in the Oliver. This means all inside is sealed well, venting off the roof as designed.

[John Dorrer]

After dumping noth tanks, I close the black tank valve and fill the black tank to 50-55%. My wife sets the counter and tells me when we hit the magic number and then I open the valve with water still spraying the tank for a few minutes. That seems to get me to clear water.

[jd1923]

On 10/27/2023 at 12:05 PM, jd1923 said:

I just started using the Pine-Sol/Calgon solution that @HDRider suggested. I learned this from the Kleen tank guy: Kleen Tank, the nationally-recognized, independent RV tank cleaning service

Not enough experience with it yet...

Planning to soon descale the water lines with vinegar and after that is good and rinsed, I will sanitize the lines with a bleach solution - WARNING!!!

Just realized you CANNOT have Pine-Sol in the black and gray tanks when working these procedures! Pine-Sol contains glycolic acid, when mixed with bleach will create chlorine gas, which is immediately lethal. Same reason we do not mix bleach and vinegar. Pine-Sol plus vinegar is not as bad, as they contain two similar acids. Pine-Sol company states specifically not to mix there cleaner with any others.

[Geronimo John]

On 11/22/2023 at 10:45 AM, jd1923 said:

Planning to soon descale the water lines with vinegar and after that is good and rinsed, I will sanitize the lines with a bleach solution.   ....    Pine-Sol contains glycolic acid, when mixed with bleach will create chlorine gas, which is immediately lethal.

The obvious most important warning is not to mix those chemicals in your living space.  More than a few folks trying to unclog/clean a sink/toilet have done so to their peril.  So good reminder.

But for this discussion (Tank and Fresh Water Line Cleaning), the solution to your process is not to mix the Pine-Sol that you put into the black/gray tanks with the the Vinegar you put into the hot and cold water lines to sanitize. 

How? 

• Raise your trailer tongue at a dump station or camp site where you have full hook-up and open the black and gray valves to drain them after your tank cleaning. 

• Then flush the water lines first with a bunch of clean water to flow water through the water and they drain into the tanks to remove any Pine-Sol residue. 

• Then introduce the bleach water into the hot and cold water lines and complete the sanitization process.

• Flush the tanks some more and close the valves.

Always remember to bypass your hot water tank.  You don't want bleach in it.

GJ

[jd1923]

1 hour ago, Geronimo John said:

Always remember to bypass your hot water tank.  You don't want bleach in it. GJ

Thanks GJ, for your well-written simple instructions. My question is, what about vinegar? I read here in a few posts to also bypass the (Suburban) HWH. Reading posts on other sites and YouTube videos show descaling the HWH with vinegar (but yes, bypass the HWH when sanitizing with bleach). What do y'all think? 

[SeaDawg]

Just don't ever mix vinegar with bleach. Not a good result.

[Galway Girl]

 

I posted this inside our closet door. 

[Geronimo John]

On 11/23/2023 at 9:43 AM, jd1923 said:

Reading posts on other sites and YouTube videos show descaling the HWH with vinegar (but yes, bypass the HWH when sanitizing with bleach). What do y'all think? 

Yes, descale HWH with vinegar. But dump it.  Keep it isolated from any bleach.  Use the hot water isolation valve to do so.  When done, then button up the HWH open the isolation valve and flow fresh water through it to purge all vinegar and scale out of the HWH.

I have attached my water systems checklists.  It has several processes with detailed steps that a new owner could follow easily.  Once you have done them a few times, it will come natural.  But I do understand not knowing for sure what you think you may not.  

Each use I find ways to improve them.  So If  you or others see errors or ways to improve them, please PM me and I'll update.   

Mahalo,

GJ

2024 WATER SYSTEMS SERVICE AND SANITIZATION (Updated 2024 Version).docx

[Steph and Dud B]

On 10/26/2023 at 2:25 PM, RustyMD said:

I used the black tank flush valve to clean it from down below (black tank drain valve closed). When I flushed the toilet there was an air pressure explosion of the obstructing material over pretty much the entire bathroom.

Air pressure should not be able to build up in any tank. They should be vented through the roof, even with the dump valve and toilet closed. I suspect the tank and part of the vent stack was completely filled with fluid. That would absolutely create a toilet geyser.