Pumping Gray Water into Black Tank

Doug1968 · July 16, 2010, 06:26:43 AM

Fellows,

I've heard the idea of having the capability of pumping some water from the gray tank into the black tank during the draining process to assist with rinsing of the solids.

If I install a pump to move water from the gray tank into the black will the pump last. It seems as though the particles in the gray tank, possibly hair etc. would shortly cause pump problems?

Does anyone have experience with this and can give me some direction.

Thanks,

Doug

TomC · July 16, 2010, 07:02:41 AM

You wouldn't want to use a fresh water pump. A centrifugal pump that is would work. Can't you just let gravity flow some water into the black tank?

I dump my black tank first, then back flush from the water hose that is usually at a dump site with about a minutes worth of water and that flushes well enough. Then dump the gray to flush out the sewer hose. Good Luck, TomC

mikelutestanski · July 16, 2010, 07:03:10 AM

Hello; My tanks are as follows 46gal black and 110 grey and 100 fresh (50 gal fresh never hooked up). Each tank has a shutoff valve; and the common line that dumps to the hose also has a valve. I can backflush some grey into the black if I choose to. The black tank does not need to be dumped as often as the grey except if the washer is used.
So when I do need to do the black I first dump the black then shut the common downstream valve off and backfill from the grey tank to the black for 30 to 40 seconds to move any lingering solids . THen I shut the grey off and reopen the black and finish dumping the black. THen I close the black tank valve and open the grey tank to dump that. Then the hose and the system is clear with just grey water through the hose. I can then rinse the hose and store it. I keep a cap on the dump line that sticks down through the bottom of the bay. THe last job is to check that the cap is secure before closing the bay.
If it was not clear; to do this your piping will require 3 valves. and a Y type connection for the tank drains. Each tank requires a shutoff and a common valve just before the drain line exits the coach. In my case the black tank is 4 inch and the grey tank is 2 inch.
Hope the explanatiion is clear enough. I have used this system successfully for about 10 years. I always fill the tanks and dump when full. I never let the grey or black tank run through when at a campground. I have seen campers that are permanently setup with the hose connected and the stuff channels in the tank and eventually cause the tank to cake and block. BY filling and dumping I keep the tanks in a fluid condition. ANd if you use 8 ounces of aqua chem with each dump the situation is improved.
Hope this helps
Regards and happy bussin mike

usbusin · July 16, 2010, 08:17:34 AM

mikelutestanski, this is the set-up we had in our 4104 and what we now have in our truck conversion.

I do as you do, with the exception, that we back flush the black tank twice and do not leave the black open on the final dump. I wait until the gray is nearly full, then after the black is dumped I let about 30-40 gallons or so go into the black. Then dump the black and repeat the process.

This worked well for us for 16 years in the 4104 and 10 years in the current truck conversion. Never a clog or hang-up with the black tank.

kyle4501 · July 16, 2010, 08:32:31 AM

We also wait until our tanks are 3/4+ full before dumping & I usually leave a little in the tank as a 'starter' for the next load. I never rinse or back flush the black tank with grey. We also don't put anything in the black tank that wasn't eaten first (except flush water). Since paper provides the biggest problem with buildup & requires more water to move down the line, we don't put paper in the black tank - we have a special trash can for the hazardous paper waste. We don't use chemicals & we don't have odors. We also have no problems with buildup in the tanks. We are also careful concerning what we use for soap & cleaners - antibacterial & chlorine are not good for the health of the good bacteria in your waste tanks.

There are many different ways to skin this cat. So, go with the way that fits your needs/ lifestyle best.

All that to say, you may not have to worry about backflushing your black tank. That could leave those resources available for other projects . . .

FloridaCliff · July 16, 2010, 08:41:32 AM

Quote from: usbusin on July 16, 2010, 08:17:34 AM
mikelutestanski, this is the set-up we had in our 4104 and what we now have in our truck conversion.

I do as you do, with the exception, that we back flush the black tank twice and do not leave the black open on the final dump. I wait until the gray is nearly full, then after the black is dumped I let about 30-40 gallons or so go into the black. Then dump the black and repeat the process.

This worked well for us for 16 years in the 4104 and 10 years in the current truck conversion. Never a clog or hang-up with the black tank.

My set up also.

Works great and not even a minor problem so far.

Cliff

FloridaCliff · July 16, 2010, 08:47:49 AM

Quote from: kyle4501 on July 16, 2010, 08:32:31 AM
We also don't put anything in the black tank that wasn't eaten first (except flush water). Since paper provides the biggest problem with buildup & requires more water to move down the line, we don't put paper in the black tank - we have a special trash can for the hazardous paper waste.

I would love to hear what your therapist says about this "hangup"......

Cliff

Len Silva · July 16, 2010, 08:52:23 AM

I'm afraid my wife would never set foot in the bathroom again

Jerry32 · July 16, 2010, 08:55:18 AM

I just use fresh water to flush the black tankand no problems with TP as it all goes through the sewer solution jet just fine. Jerry

mikelutestanski · July 16, 2010, 09:58:08 AM

Hello: THe double flush back to the black tank is a good idea and I do that if the black valve closed hard. I always close the black tank valve for the final empty of the grey tank.
I never have worried about TP it usually just is converted in the reactions.. However with 46 gal of black I generally let it percolate and only dump when its over approx 5/8 to 3/4 full.) The toilet is the only hookup into the black tank.
Formaldeyhde is the basis of aqua chem and if you do the chemical reactions it comes out to water and ? Can't remember but its not harmful. (After it does its thing and works through the matter the original chemicals are gone..) At an FMCA rally a long time ago we sat thru a presentation of that . (Each person needs to do his own research to find and use what makes them comfortable). THe sales person was fighting the other products that were supposidly safe but in the long run were not as safe becuse they did not biodegrade as well. In the past any "chemicals" in products were considered bad for the environment; and companies fired up the advertising to sell their own products. Anyway the point of this is that all chemicals are not bad or unsafe. I dont have any stock in aqua chem or any bias . If I find something better I will switch.
sometimes after long storage at home the water in the sink or washer or shower traps may evaporate so it is a good idea to run some water into each drain. We have not used any chemicals in the grey water tank.
I try to use a system that works and is as safe as I can make it.. I dont believe in dumping grey water on the ground even though many others do.
I am glad to see others who have had reasonable results with the same or similiar techniques.
FWIW regards and happy bussin mike

kyle4501 · July 16, 2010, 10:40:12 AM

Hey Mike, looks like we're doing the same thing only differently - again!

It comes down to using bacteria to break down the waste products naturally (& hope the good bacteria wins

)
-OR-
The use of chemicals (to kill as much bacteria as possible) & perfumes (to control the odor).

Formaldehyde can be useful as a disinfectant as it kills most bacteria and fungi (including their spores). When you consider how a septic system works, using bacteria to break down the solids, I don't see how using formaldehyde is a good thing. Of course, when you use natural bacteria, the chemical companies don't have as much to sell you - and it requires a little more effore on your part. . . .

For a better explanation of the dark side of waste tanks:
http://www.phrannie.org/macerator.html

BTW, with 4 of us & only 30 gallon black tank, we have to minimize the volume we put in the tank. Since I'm so full of $#!t, paper & water is all I can cut back on.

kyle4501 · July 16, 2010, 10:52:48 AM

Quote from: FloridaCliff on July 16, 2010, 08:47:49 AM
Quote from: kyle4501 on July 16, 2010, 08:32:31 AM
We also don't put anything in the black tank that wasn't eaten first (except flush water). Since paper provides the biggest problem with buildup & requires more water to move down the line, we don't put paper in the black tank - we have a special trash can for the hazardous paper waste.

I would love to hear what your therapist says about this "hangup"......

Cliff

Given the topic being discussed here - I ain't gonna bite that bait.

Joe Camper · July 17, 2010, 08:07:45 PM

Our bus was neglected and misused for a pretty significant amount of time before we got it.

In relation to this thread the secondary air dump for the waste tank was stuck closed and needed to be replaced and was plugged up when I did remove it.

Totally flat bottom tank.

Fast forward. My fuel sending unit failed and the access panel is on the forward wall of the plumbig bay so the holding tank had to come out.

I expected to find something and there was not even a trace of anything not even in the corners.

I have no grey tank and have never used the clean out.

I always put a more water in to start and try to get it 3/4 or more before dumping as frequently as I can.