A “New/Old” Way to Clean the Black Water Tank

[WayneLee]

Many years ago, an “old-timer” taught me a trick to draining and flushing my black water tank. I have used this method for over 10 years and I have never had any problems. Now that I have downsized from a Class A diesel, I am about to use it again in my Class C. I searched this forum any could not find any threads on this method.

The trick is to get your gray water over to your black water tank and use the gray water to flush out the black tank. Saves water and it actually works very well cleaning your black tank.

Now, to accomplish this, you have to have:
(1) A method of closing off the “slinky waste” hose, and
(2) You need to let your gray tank fill up, no draining early, and
(3) Both tanks should be approximately the same height off the ground, and
(4) The outlets (valves) for both tanks are reasonably close together, and
(5) You probably need to be in a full hookup site, this method takes a bit longer to drain your tanks and you don't want to hold up other people in line.

The principle of why this method works is based on the rule that water seeks its own level.

Here is the process of draining your tanks:

(1) Hook up your slinky drain hose, and drain your black tank as normal.
(2) When the tank has finished draining, do not close the black tank valve.
(3) Close off your slinky hose valve, open the gray water valve.
(4) Gray water will flow over to the black tank.
(5) When you feel enough water has transferred, close the gray tank valve. Remember to save some gray water for step (7).
(6) Now, open the slinky hose, drain the black tank and start the process over.
(7) When you are finished, close the black tank valve, open the gray tank valve, using the remaining gray water to clean out your slinky hose. Or, if you have a black tank rinse connection, you might want to give it a few “shots” which will help clean the sensors, then drain the black tank before opening the gray tank valve.

The hardest part of this whole process is assembling the necessary materials to make the “slinky hose” closing valve assembly. Most Class A's and some Class C's (not sure, mine does but I don't know if others do) have the waste valves together in the same bay. The assembly looks like a “Y”, where the gray tank and its valve, is connected to one branch of the “Y” and the black tank is connected to the other branch. The slinky connects at the bottom of the “Y”.

The companies that make waste valves, hoses, etc., use to make a piece that would connect to the bottom of the “Y” and it had its own valve. I have searched many catalogs, but I have been unable to find this type of device being made today. I left my own device in one of the RV's I sold, so I have to buy some parts and assemble my own. Many people that have maceators can use this method by simply turning off the maceator to stop the flow. In my last Class A, I had a maceator to make things easy to setup.

I think that if you try this system, you will like it and it and use it all the time like me.

[Big Bill]

It sounds like a good way ,if you dont have a black tank flush

[WayneLee]

IMO, this method is better than a black tank wash. I've had a black tank washer in all my Class A's going back to the '90's. This method will give you the "rush" of water needed to flush out the chunkies. To get the same amount of water into the tank with the black tank washer would take 5 to 10 minutes. This method takes seconds.

[caper]

The companies that make waste valves, hoses, etc., use to make a piece that would connect to the bottom of the “Y” and it had its own valve. I have searched many catalogs, but I have been unable to find this type of device being made today. I left my own device in one of the RV's I sold, so I have to buy some parts and assemble my own. Many people that have maceators can use this method by simply turning off the maceator to stop the flow. In my last Class A, I had a maceator to make things easy to setup.

They still make the shut off valve. Many members use this if their black or gray water valve does not seal properly. Check the camping world parts site and you will find the item needed.

[drc343]

Twist-on Valve - Valterra T58 - Sewer Fittings & Adapters - Camping World
Works great that is what I do to drain tanks.

[WayneLee]

That's it! Thank you for the link. Ordered it today.

[Gilpalmer]

Here is a quick, simple and cheap way of cleaning your black water tank, much simpler than above. Your hardware store should carry a bottle of slippery soap used by plumbers to clean waste lines in houses. They tend to get coated on the inside walls and reduce the waste water flow over time. Simple put it's really slippery soap that you pour a cup into you toilet with your black water tank about half full. Now just before you leave on your next driving trip put in about 10lbs of ice cubes and let the fun begin on the road. It sloshes and cleans every thing. Just be sure to drain this solution when you get to your next stop. No need to rinse after draining because that slippery soap will remain in your tank for a couple of cycles which continues to keep it clean. I think it costs around $4.95 for a quart that lasts for a long time. Good luck and love simplicity solutions to problems.

[Evereddie]

Originally Posted by Gilpalmer

Here is a quick, simple and cheap way of cleaning your black water tank, much simpler than above. Your hardware store should carry a bottle of slippery soap used by plumbers to clean waste lines in houses. They tend to get coated on the inside walls and reduce the waste water flow over time. Simple put it's really slippery soap that you pour a cup into you toilet with your black water tank about half full. Now just before you leave on your next driving trip put in about 10lbs of ice cubes and let the fun begin on the road. It sloshes and cleans every thing. Just be sure to drain this solution when you get to your next stop. No need to rinse after draining because that slippery soap will remain in your tank for a couple of cycles which continues to keep it clean. I think it costs around $4.95 for a quart that lasts for a long time. Good luck and love simplicity solutions to problems.

Except for the ice cubes your use of slippery soap describes what many are using to treat their black tanks: The Geo Method. It uses laundry water softener. Look it up.

[samcunningham]

Never heard of slippery soap..and my Dad was a plumber. Do you have a photo of the container. I would like to try

Thanks.

Sam Cunningham
Orange City, fl
Big Horn 5th wheel

[jking46]

We normally camp with electric only, no full hookups. Before we leave, I nearly empty the fresh water tank into the black tank. Just hold the toilet valve open for a few minutes. Add a squirt of Dawn dish soap and drive to the dump. All the water in the tank gives it a good flush. After dumping add some more water to the black tank, another squirt of Dawn, and you're on your way. Easy and works great.

[bob caldwell]

Liquid calgon.....hard to find

[Joe O]

Best way to make sure the black water tank is completely clean (which most people don't realize, that just using the backwash valve does) is to connect a clear elbow between the end of the end valve and the slinky. Once this is done, and you have emptied the black water tank, I find, the best way to make sure the tank is completely clean (especially important when storing the RV for an extended period of time) is to dump about 6 or 10 toilet bowls full as this creates a gush of water and you can make sure all the solids are gone while looking at the clear elbow.

I like your idea, but I am concerned that you might get some backwash of black water into the grey tank before closing the grey tank valve.
I like the plumbers slippery soap idea (I'm not sure if Home Hardware here in Canada has that), but my concern with that is that it would hamper the effectiveness of the black water tank chemicals that breaks down the solids.

Joe O

[Ray and Ann]

If you have grey and black drains through a single hose connection, look for a device tagged as "Flush King". It has a shutoff valve that will allow backfeeding of grey water into the black tank in order to help rinse the black tank, and it's made with clear plastic--so you can see how well you're getting the black tank cleared out. It is important to not feed black water to the grey tank, so you have to pay attention to which of three valves (black, grey and Flush King) you're opening and closing. Our trailer has a black tank flush, but the Flush King makes it easier to do a better job.

[rockfordroo]

Originally Posted by bob caldwell

Liquid calgon.....hard to find

Calgon normally comes in powder form, so you don't need to use liquid calgon, although I prefer it when I can find it.

Walmart sometimes has it.

[rockfordroo]

Originally Posted by Gilpalmer

Here is a quick, simple and cheap way of cleaning your black water tank, much simpler than above. Your hardware store should carry a bottle of slippery soap used by plumbers to clean waste lines in houses. They tend to get coated on the inside walls and reduce the waste water flow over time. Simple put it's really slippery soap that you pour a cup into you toilet with your black water tank about half full. Now just before you leave on your next driving trip put in about 10lbs of ice cubes and let the fun begin on the road. It sloshes and cleans every thing. Just be sure to drain this solution when you get to your next stop. No need to rinse after draining because that slippery soap will remain in your tank for a couple of cycles which continues to keep it clean. I think it costs around $4.95 for a quart that lasts for a long time. Good luck and love simplicity solutions to problems.

Ice cubes don't do all that much, per this guys experiments:

https://www.youtube.com/watch?v=iH6acEmqvcw

[bob caldwell]

Powder form is a whole lot easier to find...

[madmaxmutt]

Originally Posted by Ray and Ann

If you have grey and black drains through a single hose connection, look for a device tagged as "Flush King". It has a shutoff valve that will allow backfeeding of grey water into the black tank in order to help rinse the black tank, and it's made with clear plastic--so you can see how well you're getting the black tank cleared out. It is important to not feed black water to the grey tank, so you have to pay attention to which of three valves (black, grey and Flush King) you're opening and closing. Our trailer has a black tank flush, but the Flush King makes it easier to do a better job.

Originally Posted by rockfordroo

Ice cubes don't do all that much, per this guys experiments:

Neither does the Flush King. . .

https://youtu.be/dfTd0Slt_cU

[Forester Fred]

Originally Posted by bob caldwell

Liquid calgon.....hard to find

Walmart has had it in stock every time I look. My local grocery store started carrying it too. I buy 2 or 3 bottles at a time so I've got backup.

[nomad297]

Originally Posted by Gilpalmer

Here is a quick, simple and cheap way of cleaning your black water tank, much simpler than above. Your hardware store should carry a bottle of slippery soap used by plumbers to clean waste lines in houses. They tend to get coated on the inside walls and reduce the waste water flow over time. Simple put it's really slippery soap that you pour a cup into you toilet with your black water tank about half full. Now just before you leave on your next driving trip put in about 10lbs of ice cubes and let the fun begin on the road. It sloshes and cleans every thing. Just be sure to drain this solution when you get to your next stop. No need to rinse after draining because that slippery soap will remain in your tank for a couple of cycles which continues to keep it clean. I think it costs around $4.95 for a quart that lasts for a long time. Good luck and love simplicity solutions to problems.

I have been a plumber since 1982 and I have never heard of "slippery soap." Also, the ice cube method of cleaning/scrubbing the black tank has been proven to not work. The ice does nothing.

Bruce

[bob caldwell]

Guess I need to find a higher class Wal-mart