Black tank empty after draining?

[mtofell]

In case you are wondering about lingering odors in the black tank let me share a recent experience: A couple things going in - First, you probably don't want to read this is you're eating dinner or just have or are just about to. Second, I always put at least 3 gallons of water in my tank after dumping, likely way more. I just let my outdoor kitchen sink (empties to black tank) run for several minutes. As best I can estimate the faucet puts out at least 1.0 GPM (gallons per minute and yes, I work in a related field and am pretty aware of this type of thing).

Anyway, I got one of those clear sewer fittings and while packing up Sunday at an RV park, decided to do a little flushing/cleaning (I don't have an auto-clean). So, I emptied the tank, filled it with a few gallons, emptied and so on. I repeated this pattern 15+ times and was totally amazed at the solids and debris being dislodged well after 10+ fills and dumps. The water coming out would go nearly clean and then.... well, not clean As in, large solids and TP that had just been dislodged.

I had just always pictured the black tank as a funnel. I'm now thinking it's more like a large flat box with a drain at one corner.

So, I highly recommend the clear fittings (if you have the stomach for it) and doing the some rapid draining-filling-draining, etc. You might be amazed at what comes out

And my 5th wheel is 2 years old and has had pretty light use.

[BFlinn181]

Most black and grey tanks are just flat boxes, they can get the greatest capacity for the least space and it's easier to build support for a flat box rather than a funnel-shaped bottom. I suggest putting a little detergent (Dawn works well) and/or some Calgon Water Softener. Both break the surface tension in water and make it 'wetter' to wash debris off the walls of the tank and soften and deposits. Laundry detergent also works, I use Dawn because it is a good grease cutter.

I usually add these 'wetting agents' during the last day before returning home. I can dump at home through a basement drain, the drive stirs things up and helps wash down the walls. I do also have two tank rinsers to help with multiple fill and rinse cycles.

The video is a demo of what's going on in your tank, I'm also impressed that none of the steps shown fully clean a black tank like we'd like to thing they do.

https://www.youtube.com/watch?reload=9&v=dfTd0Slt_cU

[JDT]

I've had the clear sight tube on mine for quite a while. I hate watching it but it is the only way I know for sure the black tank is coming clean.

I just recently bought a macerator pump for mine. Not sure it will help it drain any better but I've run into several situations where the drain was either level or slightly uphill to include the dump I have in our rv garage. Awfully tough getting $#!% to run uphill. Also, things tend to get stuck in the folds of the hose and come out at inopportune times. The macerator hose is only one inch and slick inside.

[Old-Biscuit]

My black tank and grey/galley tanks all drain thru common header.

I installed an extra drain valve on the horizontal run of that common header

I also use a clear adapter on between end of drain header and sewer hose

After connecting stinky slinky I open grey tank drain valve and header valve to check for any leaks.
Then close grey tank drain valve

Open Black tank drain valve.......when it is just a trickle via clear adapter I close the header valve and open galley tank valve which allows the galley tank to back flush into black tank.

Then I open header valve and let both tanks drain.
Close galley tank drain.....close header valve/open grey tank drain and again flush grey soapy water into black tank.
Open header valve and drain both tanks.
Close tank and header drain valves


Fill toilet bowl FULL & flush twice so black tank stays wet


NEXT--------

[dskyward]

Agreed, the flush hose does not get everything. I got the clear adapters at both ends for verification. However, I learned a good trick from the Fagan’s on roadslesstraveled.com, it is to carry two 5 gal buckets and fill both full and carefully carry up the stairs into the rig and pour down the toilet (as rapidly as possible) AFTER draining the black tank to a trickle. The shear weight and force of all that water crashing down on the bottom does an incredible job at dislodging and flushing out the old stubborn waste, if you’ve never done this. This can certainly save time if you’re at at the dump station with a line, rather than the long ordeal of hooking/unhooking your black flush hose. So, fill up your bucket with water while emptying the black tank, or fill em up sooner at the campsite, put a lid on it. Walmart sells them for $1.60 ea. You will be amazed at what comes out. I’ve done 4 buckets (when time permits) and still see murky water come out, like you just opened the valve. Of course you may have a spotter outside to see and report these things firsthand, as you can’t get out and around in time to see the tidal wave, but it still takes about 30 seconds to drain 4 of the 5 gallons you rushed through, so you have time to catch the view. Then, take turns and haul another bucket up for the misses to pour in (giving you 20 secs delay) and go round to see what else got missed. I’ve seen old toilet paper come out from a friend’s visit over a month ago. We don’t EVER put toilet paper of any kind down our black tank. We’ve read horror stories even with the use of RV toilet paper causing clogging issues or interfering with the valve in the black tank. We installed a sprayer wand and it dramatically saves on toilet paper that we roll up and dispose of in a lid trash can and empty on a near daily basis. We’ve full timed now on 2.5 years with zero issues. Yes, Dawn detergent works well (2x/mo), but don’t ever expect your factory sensors to ever be correct again.

Sorry for the long post, hope this has helped some newbies and some seasoned.

[mtofell]

Originally Posted by Old-Biscuit

My black tank and grey/galley tanks all drain thru common header.

I installed an extra drain valve on the horizontal run of that common header

I also use a clear adapter on between end of drain header and sewer hose

After connecting stinky slinky I open grey tank drain valve and header valve to check for any leaks.
Then close grey tank drain valve

Open Black tank drain valve.......when it is just a trickle via clear adapter I close the header valve and open galley tank valve which allows the galley tank to back flush into black tank.

Then I open header valve and let both tanks drain.
Close galley tank drain.....close header valve/open grey tank drain and again flush grey soapy water into black tank.
Open header valve and drain both tanks.
Close tank and header drain valves


Fill toilet bowl FULL & flush twice so black tank stays wet


NEXT--------

So, that would be similar to 1 of my 15 drain/fills. I was 10+ and still getting all kinds of "stuff". fwiw, I have a macerator which acts as a valve - I just turn off the device and open the gray after emptying black while leaving the black open. I thought that was doing the job but I'm thinking not completely.

I did vary the amount of water I was filling with and found that after a couple gallons it really didn't matter. When filling with 5+ gallons I'd get 4 gallons of 99% clean water and 1 gallon of brown water near the end With 2 gallons of fill I'd get 1 gallon of 99% clean and 1 gallon brown water. I found the "sweet spot" for cleaning/flushing to be around 2 gallons. My biggest takeaway is to either buy an RV with a flush system or get one of those wands to put down toilet to spray and clean. Draining/filling a couple times just doesn't dislodge enough of the solids. Of course, this may just be something inherent to my RV and it's tank. I have had some unexplained odors in the past.

[dskyward]

Another helpful hint when draining the black, is to drain when at least 2/3 full. Yeah, sounds funny. No really, the fuller you get your black tank, the better drain you’ll have, provided you have a good drain hose slope. Our black is 50 gallons capacity, and I always estimate to leave 5 gal(w/chem of course) to start a new cycle, especially when traveling as the DW has to stop more often, and how convenient it is to have your bathroom travel with you! We keep a full gallon water jug next to the toilet for those on the road emergencies or when the CG supply gets shut off, as we normally don’t travel with water in the fresh water tank. We’re not boondockers, but it has happened to us on 3 occasions (upon arrival or next day) through 107 campgrounds in 2.5 years that the water supply unexpectedly got turned off (leak repairs and failed well pumps), so we’re learning it is necessary to have fresh water in your tank while traveling. And with that, the chore of replacing it routinely.

[BFlinn181]

Perhaps some folks should not use the black tanks at all, just use campground or rest stop restrooms. Think of the water you'd save! Might even end the water crisis in some places.

[Cumminsfan]

Here's all you need to know.

https://www.youtube.com/watch?v=dfTd0Slt_cU