34 replies to this topic

[Brianwl]

Okay folks I did a search using "flush" and came up with a ton of posts but didn't see any topics like mine so I thought I'd post it.

My plan is to have a 100 gal fresh water tank and a 100 gal waste tank on my HDT when I get it and do the build. I have 3 - 50 gal tanks (fresh, grey, and black, plus a galley tank which is smaller) on my 5ver

However, in thinking about this and was wondering if I should have a 100 gal black tank and a 50 grey tank on the truck instead of a single 100 gal waste tank. That way I can run a hose from the grey tank off the truck and use that water to flush my 5ver's black tank.

How do you boondockers handle the black tank flush so that you don't waste to much precious water?

[Rif]

Brian,

I have a 90 gallon gray tank and a 50 gallon black tank on my 5er. I have a single 100 gallon waste tank on the HDT. I dump the gray tank at least 4 times to every one time I dump the black, and usually more. It will normally last up to 4 weeks for the two of us.

I use an additional valve mounted on the end of the dump connection. Both my tanks share that single dump connection and the actual valves for each are buried inside near the actual tanks. When it is time to dump the black I open both the black valve and the connection valve, and pump to the HDT using the macerator. When it is empty I close the valve on the connection, open the gray valve and let the water from the gray tank flow back into the black tank. When the tanks equalize I close the gray, open the connection valve and pump it out. I usually do that about three times. That gets the black tank very clean.

The secret is to have that extra valve on the connection. In addition to using it for dumping as outlined, it is also a safety in case one of the other valves leak. A third purpose is served if you have a washing machine that is not plumbed into a tank, but that is plumbed directly to the dump line. My Teton is plumbed this way. We are still able to use the washing machine when boondocking by opening the gray valve and leaving the connection valve closed. This way the washing machine water can flow back into the gray tank. Naturally we have to keep an eye on the water level.

[Stanley P. Miller]

We didn't bother flushing the black tank when boondocking, it got near enough empty with just a dump and a toilet couple bowls flushed down to clean the black valve/line a bit. Dumping the gray took care of flushing the shared lines and hose.

By the time we got to the next campground or dump station the movement had the tank pretty much all liquified and easy to dump.

[Brianwl]

We didn't bother flushing the black tank when boondocking, it got near enough empty with just a dump and a toilet couple bowls flushed down to clean the black valve/line a bit. Dumping the gray took care of flushing the shared lines and hose.

By the time we got to the next campground or dump station the movement had the tank pretty much all liquified and easy to dump.

That works for boondocking between campgrounds. I plan to boondock for months at a time if I can find a place to park.

[Stanley P. Miller]

There are fewer dump stations available now but finding one should be possible from time to time. Even without a dump doing a dump to your truck's tank after a trip will get most of the solids out of the tank.

Finding a place to park won't be that hard in a lot of places, finding a place to dump the black tank or the truck's black tank may prove to be more of a challenge.

[Happy Prospector]

I boondock most of the year and dump my tanks with a macerater to a 100 gallon waste tank on truck. When I finish pumping the black tank, I run macerater hose in bathroom window and pump the shower water into the toilet and then reflush black tank into waste tank. This has worked well for 6 years.
I will be plumbing a hose from the utility cabinet to the black tank so all I will need to to is hook up the end of macerater hose to this new hose to pump in my shower water to flush the black tank instead of going in bathroom window. I am looking into this now and researching anti back flow valves for this new hose.

Edited by Kevin, 21 April 2012 - 05:12 AM.

[Keeland]

Perhaps I just don't understand what everyone else is saying in the posts above, but here is my question. I have a Class C with the normal fresh water, black water, and grey water tanks. In the command center inside the RV I can easily check the volume of each tank. When I dump the black water tank I then use a garden hose hooked to an inlet that sprays into the black water tank to help clean it out. This is done as soon as possible after driving the RV so that any movement helps loosen debris in the black water tank. I run the flush water until water coming out of the black water tank is clear and then I completely drain the black water tank. If I then go in the RV and use the command center to check the volume of the black water tank (which should indicate empty) I still see a volume of 1/2 to 3/4 full. I assume that this is cause by 'stuff' stuck on whatever kind of volume sensor the tank has. How can I really clean out the black water tank such that the command center shows a true value of empty? Thanks for any reply.
BobK

[Mark & Dale Bruss]

Like Rif, we have a third valve on the end of the discharge pipe. We originally installed it because while traveling, the small amount of fluid in the Black and Grey water pipes, after their valves, would setting at the cap at the end of the discharge pipe and release when we took the cap off. Not a lot but messy.

Since then we found that when we are using a macerator, when we do laundry, we close the output valve and let the washer water backup into a waste tank, but we do the Black tank. This is after dumping the Black tank first. We figured the soapy water would help breakup stuff in the Black tank. We can do three wash loads before we run the macerator.

I have read of several people who have a lot more Black tank capacity than the Grey tank capacity needed. So they install a pump with a check valve to move fluid from the Grey tank to the Black tank to extend boon-docking time.

[sandsys]

How can I really clean out the black water tank such that the command center shows a true value of empty?

If you find a way will you, please, let the rest of us know? Many have tried but I'm not aware of anyone who has succeeded except those who cheat by installing exterior sensors to replace the interior ones that don't work.

Linda Sand

[Mark & Dale Bruss]

Or you could take out the original sensors and clean them.

The external sensors are easier to deal with.

But then again, there is the decidedly different sound when a toilet flushes into an almost full tank that is more reliable than any sensor system.

[Stanley P. Miller]

Lots of different options, the one I like best is a cleaning wand put down the toilet that blasts the sides of the tank with a stream of water. You can find a good variety for sale or make your own for a fraction of the store-bought price.

[breed]

I use a wand made from a 1/2" pvc pipe with a cap on the end and a little hole drilled in the side of the cap.to spray in the tank from the toilet. very easy to make.

[Keeland]

Well, considering that pretty much everything under the floor in the RV is hard to get to, I guess that removing the interior sensors is not an option that I'm interested in trying. Listening for the sound of a full tank while flushing is possible, but I'll probably take the advise of Stanley and breed to make a cleaning wand from 1/2" pvc. Sometimes pvc is like duct tape - lots of uses.

[Bob Cochran]

Brian

Your going to be able to move ti pretty soon!!! That will help a lot keeping build up down and the smell.Then again maybe the smell will go along with the truck motif.

Edited by Bob Cochran, 23 April 2012 - 08:26 PM.

[Brianwl]

Bad to the Bone is going to have a 100 gal fresh water tank and a 100 gal waste tank on it. But I'm thinking maybe I need to split the waste tank into 2 tanks, one for grey and one for black so that I can use the grey tank to flush the black tank. Thoughts?

[Rif]

Brian,

I don't see the need. The purpose of the waste tank on the truck is to haul the waste to a dump station. All dump stations I've ever run into have hoses and water to flush the tanks with.

[Brianwl]

Rif,

I meant flushing the black tank on the 5vet, not the one on the truck.

[Rif]

Brian,

Sorry. Misunderstood. In that case refer to my first post in this thread and to Mark Bruss's. Just install a valve on the end of the discharge line and use gravity to do the flushing. I've been using this technique for several years, and sometimes for two or three months at a time. It really does clean out the black tank. There's no need to make dumping with a macerator any more complicated or time consuming.

[Brianwl]

Brian,

Sorry. Misunderstood. In that case refer to my first post in this thread and to Mark Bruss's. Just install a valve on the end of the discharge line and use gravity to do the flushing. I've been using this technique for several years, and sometimes for two or three months at a time. It really does clean out the black tank. There's no need to make dumping with a macerator any more complicated or time consuming.

Rif,

Thanks. Can you post a pic of your setup, both the dumping set up and how your tanks are set up on the HDT?

[stolpsaddles]

Most places I bon-dock are dry and sandy. Dig a small hole to drain the grey water and I am good for 3 weeks with the black water.