Grey and Black water tank maintenance

This was copied fro tricks and talk back an seems pretty good.
It has not been edited in any fashion.

Everyone who owns an RV should be concerned with maintaining its wastewater tanks. Problems with wastewater tanks can and should be avoided. Wastewater tank repair is expensive. Due to health concerns, many service facilities will not work on wastewater tanks and lines until the tanks have been completely emptied and sanitized. This may be quite difficult when the tank(s) is in need of repair. So, common sense dictates that the tanks should be kept relatively clean at all times. Additionally, improper use of the wastewater tanks can lead to a build up of solid wastes, which in itself may cause the system to fail.

I've discovered very simple, effective, and inexpensive methods of maintaining my wastewater tanks in a relatively clean condition at all times. I developed these methods myself through my understanding of chemistry, physics, and biology with a smidgen of common sense thrown in for good measure. I also read my RV owner's manual. Although we are not full time RVers we use our fifth wheel camper at least one weekend a month. We never use public bathing and toilet facilities. In other words, our wastewater tanks are fairly heavily used. Since I've met a number of RVers who don't seem to know how to maintain their wastewater tanks I thought many RVers would find my tips useful. If you have not been maintaining your tanks I believe you will be pleasantly surprised the first time you employ these tips. I do these things and they work.

RVs are equipped with waste water HOLDING tanks; NOT septic tanks. Those holding tanks are nothing more than chamber pots. Chamber pots should be cleaned and sanitized after their contents are disposed of. The Geo Method is based on this fact.


When you are camping and your RV is connected to a sewer/septic intake, leave the drain valves closed until the tank is full and ready to dump. Dumping a full tank provides a sufficient quantity of water to flush solids from the tank. Leaving the drain valves open allows the water to drain off without flushing out solid waste. That solid waste will collect in the tank(s) and cause problems over time. If your tanks are not full when you are ready to dump them, fill them with fresh water first, and then dump them.


In other words, dump the black (commode) water tank first, then dump the galley tank, then dump the bathroom tank. This way you will be flushing out the dirtiest water with progressively cleaner water.


This stuff is amazing and it works. Buy a couple of boxes of powdered water softener at the grocery store. You'll find it located with or near the laundry detergent products. I prefer Calgon Water Softener because it dissolves quickly in water. Cheaper water softeners work just as well but dissolve more slowly. Dissolve two (2) cups of the water softener in a gallon of hot water. Then, pour the solution down the drain into the empty tank. Use two cups of softener for each wastewater tank in your RV. The tank's drain valve should be closed otherwise the softened water will just drain out. Then use the tank(s) normally until it is full and drain it normally. Add a cup of laundry detergent to the black (commode) water tank at the same time you add water softener. This will help clean the tank. The gray water tanks should already contain soap through normal use.

The water softener makes the solid waste let go from the sides of the tanks. If you've ever taken a shower in softened water you know that after rinsing the soap from your body your skin will feel slick. That's because all the soap rinses away with soft water. Softened water also prevents soap scum from sticking in the tub. Get the connection? With softened water gunk washes away instead of sticking. The same thing applies to your RV's wastewater tanks.

I use a clear plastic elbow connector to attach my sewer drain line to the wastewater outlet on my RV. It allows me to see how well things are progressing during a wastewater dump. Before I began using water softener regularly the black water tank's water was brown, the galley tank's water was brownish, and the bathroom tank's water was white. The first time I added water softener to the tanks the water coming from the black water tank was actually black (not brown) and the kitchen tank's water was also black (not brownish). The bathroom tank's water remained white. That told me that the water softener had actually done what I had intended for it to do and made solid waste, which had been stuck to the interior of the tanks, let go and drain away. I added water softener (and laundry detergent to the black tank) to all the wastewater tanks for the next few dumps to be certain all the solid waste possible had been cleaned away. The wastewater only appeared black on the initial treatment. I now add water softener and detergent to each tank once after every few dumps to maintain the system.

Too little water softener may not be of sufficient concentration to work effectively. Too much water softener will NOT hurt the tanks. So, if the amount you used didn't quite do the job, then use more the next time. Don't forget the laundry detergent.

Occasionally, I pour a half gallon of liquid bleach into each tank to deodorize, sanitize and disinfect them. I add the bleach when the tank is about half full, and then continue to use the tank normally until it is full and ready to dump. I no longer use the blue toilet chemical because it isn't necessary. I have no odors coming from my black water tank. The chlorine bleach kills the bacteria, which is primarily responsible for waste water tank odor. Generic brand liquid bleach is cheap and very effective.


Most fresh water contains sediment. Sediment will accumulate in your wastewater tanks and your fresh water lines. It also tends to discolor your sinks, tub/shower, and commode. I use the disposable type and have found that they eventually fill up and begin restricting the fresh water flow resulting in low pressure. That's how I know it's time to get a new filter. It works, it's cheap, it avoids problems, do it. When I fill my fresh water tank I attach the filter to the end of the hose and fill the tank with filtered water.


WATER, WATER, WATER - and more water! The Geo Method assumes you are hooked up to a plentiful clean water supply, and that you have access to a sewer. The water softener will make the gunk let go. That's only half the battle. After the gunk lets go it must then be flushed through the relatively small drain opening in the bottom of the tank. That takes water. Lots of water.

Will The Geo Method work even if most of the time I'm NOT hooked up to water and sewer? YES! Just use common sense. If you dry camp ninety percent of the time just keep water softener and detergent in your tanks (especially the black tank) while you're dry camping. This will keep gunk from sticking to the tanks. When you are hooked up to sewer and water take the opportunity to fill the tanks with fresh water and flush the tanks. Keep flushing them until the water runs clear. I know it works because I've done it.

Never put regular toilet tissue in your RV's black tank. Only use toilet tissue which is approved for RV and/or septic tank use. Regular toilet tissue may eventually dissolve, but not before causing a clog in your black tank.

I believe occasionally traveling with partially filled wastewater tanks that contain softened water promotes cleaning by agitating the water. The same goes for chlorine bleach.

I believe this process works faster and more efficiently during warm weather. However, I know it works well even during cool/cold weather.

I believe the process works best the longer the water softener remains in the tanks. So, I don't add water softener during periods of heavy wastewater generation. I wait until I know we won't be generating wastewater quickly so that the softened water remains in the tanks for several days before dumping.

If you have an older RV you may have to use water softener and detergent several times initially to completely clean the tanks of residue.

I add a small amount of chlorine bleach to the fresh water tank twice a year to disinfect and sanitize the fresh water tank and fresh water lines. A weak chlorine bleach solution will not hurt you. However, it certainly makes the water taste bad. When we have chlorine in the fresh water system we use bottled water for drinking and cooking until the chlorine is gone. YES, we drink the filtered water that we have in the fresh water tank. NO, it has never tasted funny or caused any problems.

No, I do NOT do the ice cube thing. The Geo Method works just fine without ice cubes.

My tanks are plastic and my pipes are PVC.

Don't be afraid to use your tanks. Just use common sense about their care and maintenance.

These tips are inexpensive to do. Some of them don't cost anything. You have nothing to lose in trying them and I encourage you to do so. I actually feel a certain amount of pride in the condition and cleanliness of both my waste and fresh water systems. Naturally, these tips make dumping a much more pleasant and sanitary procedure.

If you have odors in any of your water systems these procedures should eliminate them. Odors indicate a sanitary problem and degrade the enjoyment you derive from your RV.

When my RV is parked and not in use I place stoppers in the sink and tub drains. This forces the wastewater tanks to vent through the vent pipes to the outside instead of through the drains into the RV. Water evaporates. Once the drain traps dry out during periods of non-use, nothing is there to prevent gasses (odor) from venting into the camper. Use stoppers when your RV is stored.

Copyright(c)Charles Bruni

Please consider printing this information and posting it on bulletin boards in RV parks and campgrounds you visit. Fellow RVers will benefit from your consideration.
Grey and Black water tank maintenance

Poppa, thanks for the info. Been traveling a long time and this is the best article I have seen on the subject. :cool:
Grey and Black water tank maintenance

Thanks Poppa. This is the first time I have seen all the info on tank maintenance in one place. Definitely a keeper!

P.S. This article should be made a 'sticky'

Grey and Black water tank maintenance

Poppa, Thanks for the detailed tank maintenance procedures. However, Everything I ever read before mentioned that the micro organisams and bacteria had to work to break down the waste and to never use bleach in the black tank because it worked against this. The same would hold true for septic systems. What do you think? Your technique sounds better and makes sense useing water softener. Maybe we'll get some more input. Thanks again, John H....
Grey and Black water tank maintenance

Poppa, OK, I brought the MH out of storage yesterday and I'm buying some water softener today and will try this new way. Thanks again for the article. John H....


Senior Member
Grey and Black water tank maintenance

POPPA, I don't know just where that came from, but the chemist that I know, as well as several other RV sources say that the Calgon theory is pure folk lore. I have never tested it so I am wondering just who the author is, and what is his expertise? I would like to see his supporting proof. And to pour bleach into the tank? That will kill all of the bacteria as chlorine is not selective but kills all bacteria and if strong enough will even kill you. And Thetford also cautions aginst such actions stating that it will damage the seals in the black system.

The rest of it does make some sense, but the real key is the water use. Natural bacteria will liquify the solids in your black tank if you give them the chance. The people that I talked with state that the entire Geo system is a product that does belong in the black tank!
If it works, publish the research to support it.

And to those who choose to follow the suggestions, just keep in mind that you will be the one who pays if it does not work. Neither POPPA or the author will be around to help if your tank fails to empty one day.
Grey and Black water tank maintenance

To read an extensive discussion of The Geo Method click the link below.

The original Geo Method discussion thread:

"And to pour bleach into the tank? That will kill all of the bacteria as chlorine is not selective but kills all bacteria and if strong enough will even kill you." Kirk

Municipal water systems all supply chlorinated water. That's what comes out of your faucet. You drink it, shower in it, cook with it, etc. I'm suggesting pouring bleach into half full black and gray tanks to sanitize them. The traps prevent gasses from venting into the rig. The tank vents allow fumes to vent to the outside.

I assume people exercise common sense. I figure if folks can figure out how to use chlorine bleach in their laundry without killing themselves and their families, that they can figure out how to pour some into their waste water tanks. Breathing gasoline fumes can kill you too, but most of us can fill our vehicles without doing something so incredibly stupid and careless that we keel over dead at the pump, or blow the place up. Don't somke at the gas pump and don't huff gasoline. Don't pour a half gallon of chlorine bleach down the RV commode, then hold the valve wide open while sticking your head well into the commode and breathe deeply.

Having said that, I agree that if you think you're too dopey to use chlorine bleach without harming yourself then, by all means, refrain from its use.

And, Kirk, you know exactly who I am. You're the Kirk from Livingston, Tx, on RVnet - Right? You also know that Airstream endorsed The Geo Method in their June 2004 newsletter. You know EXACTLY where this came from. Acting as though you don't is deceptive. I suspect, Kirk, that you're just one of the Eco-Kooks trying to save the planet by culturing bacteria in your holding tanks. I prefer to have mine disinfected, clean, and odorless. You're absolutely correct about one thing; The Geo Method will kill ALL the bacteria/germs in the holding tanks. That was my intention when I developed it.

"RV sources say that the Calgon theory is pure folk lore...The people that I talked with state that the entire Geo system is a product that does belong in the black tank! If it works, publish the research to support it. " Kirk

It's not the Calgon theory, it's The Geo Method. Keep your facts straight - but you're not interested in facts, are you? It was a theory when I first thought to do it. I have proven it in my RV, as have many other RVers in their RVs. You wouldn't know about that because, by your own admission, you haven't tried it. You don't know what you're talking about.

I have supporting links for the ingredients in the original thread on RVnet. You know that because you've seen them. Research? You're joking, right - or just being deceptive again? This is high school science, and common household cleaning. You don't need to be a chemist to understand what detergent, water softener, chlorine bleach, and water will do to dirt. Suggesting that you do is utter nonsense - and deceptive. For some unknown, and ill informed reason, you're just trying to dissuade people from trying this and getting their tanks clean and sanitary. You demand supporting evidence. Yet, you provide none to support your objections other than the "People" you talked to, and "RV sources." Wow! That certainly supports your objections. More deception. I don't care what Thetford says. I have a Thetford commode. Chlorine bleach has done it absolutely no harm.

"Natural bacteria will liquify the solids in your black tank if you give them the chance." Kirk

Plain old water dissolves feces and toilet tissue within hours. You don't need bacteria. However, the dissolved solids tend to stick to the insides of the tanks in a hard water solution and create an unsanitary nightmare and odors. The Geo Method cleans the tanks and kills the germs. With clean tanks there's nothing for bacteria to live on, and no job for them to do. The tanks will be clean, sanitary, and won't stink. I don't want bacteria. I want clean tanks.

".. but the chemist that I know..." Kirk

On RVnet this chemist was your daughter, or did you forget? You must do better at keeping these things straight. You just posted that the other day. If your chemist daughter doesn't know what water softener does, tell her to go back to the college or university that awarded her degree and ask for her money back. However, I suspect that this is made up deceptive nonsense too. PULEEZE..

I've been using The Geo Method for several years now with absolutely no ill effects to anything. You haven't tried it. I submit that you, sir, are the one who doesn't know what you're talking about. Many other people are using The Geo Method and have posted their results in the above thread. RV plumbing is no different from household plumbing. Bleach doesn't wreck washing machines, or household plumbing. It doesn't harm RV plumbing either.

It's not a matter of opinion. It is a matter of INFORMED opinion. In other words, someone who actually knows something about what he, or she, is rendering an opinion on. What a novel concept, huh? -- To actually know something about what you're talking about! -- BEFORE you open your mouth and reveal the depth and breath of your ignorance.

The original Geo Method post contains links that support what I proposed. There are links that explain sewage treatment, chlorine bleach, detergent, etc. Then the dopes interject with statements like, "Chlorine bleach is acid. Don't use it!" Actually, chlorine bleach is a base, the opposite of acid. I learned that in tenth grade. How about those who caution, "Chlorine bleach eats plastic! Don't use it or it'll rot your tanks!" They seem to have never noticed that chlorine bleach is sold in PLASTIC jugs. So much for those dopes. Given time, and a whole lotta typing, I could refute every argument against The Geo Method with bona fide links to scientific articles from reputable sources. That's because The Geo Method is based on high school science. INFORMED opinion is based on valid, reputable, researchable, information. It is not based on what some guy has in his silly head who doesn't know the difference between an acid and a base, or the difference between his acid and a hole in the ground.

Is everyone entitled to an opinion? Sure, but that doesn't mean that everyone's opinion is worthy of consideration.

Will I take the time, and make the effort to refute every ignorant objection raised about The Geo Method? No. If you doubt the merit of what I've proposed, then research it for yourself, or don't use it. Let's suppose I actually took the time and trouble to refute the dopey objections and criticisms; do you think for minute the dopes who slept through high school chemistry class would take the time to read the refutation - much less understand it? I don't.

So, criticism is fine so long as it's based on something other than erroneous notions that happen to be bouncing around the inside of some fool's head. That's what INFORMED opinion is. Those who have criticized The Geo Method are REAL long on unsubstantiated silly notions and opinions, and real short on anything to validate, support, back up, prove, or lend credibility to their OPINIONS.

Can well informed reasonable people arrive at differing opinions when presented with the same facts? Yes, but that's NOT what's happening here. The critics usually just plain don't know what they're talking about, obviously haven't even tried The Geo Method, and just spout nonsense off the tops of their mostly empty heads.

By the way, try adding water softener to your laundry loads, carpet shampooer cleaning solution, and the soap bucket when you wash your vehicles and RVs. The difference is substantial and noticable.

I'm hitting the road in the morning on a trip that will last several weeks. I won't have internet service while I'm gone. I'll check this forum when I return.

Regards to you all. Don't pay Kirk any mind. The Geo Method is safe, effective, and cheap. Try it; you'll see.


Senior Member
Grey and Black water tank maintenance

quote:And, Kirk, you know exactly who I am.


Now there is an excellent example of the reason that I question this author. He does seem to know who I am, more or less, but then that really isn't all that difficult since I an not afraid to use my name when I post and I use it on all forums that I visit. But I have no idea who you are and that is the reason that I asked. And I also have no idea what has been published in the Airstream newsletter, although I suspect that it is from the owners club, and not Thor who manufacturese them. And I also know that the review of it that I read in another RV publication was very negitive. I did not do his research either, so I only say that it gives reason for doubt. Also, I suspect that the reason for the fact that the so called "Geo Method" is supported by a poster with your name may indicate that you are the "scientist?" who did the research. Yes, the chemist is my daughter or actually daughter-in-law, but she does have a masters degree in environmental chemistry. Just what is your background and what qualifies you for this expertise? I do not say that what your are pushing will not work, I just question the validity of the supposed research. I know many fulltimers who use no additives at all and I am one who seldom does. I do agree that laundry detergent mixed with water when traveling will clean the inside of the water tanks, as it is exactly what I do, as I have posted before. And I know from experience that plain water will do exactly what you claim to have discovered for you "magic" formula. So why waste the money buying what you suggest? Do you own stock in Calgon?

If you can support your suggestions with some valid scientific research, do so! I would have no problem with it when valid. I might even give it a try. But what you publish is your personal opinion.

Do you plan to pay for the repairs required if folks follow your suggestions and then have problems? Come out of hiding and tell everyone who you really are, then you might have more validity. I did not say that your system doesn't work, only that I still have seen no real support for it, except on your site. When I do, I'll support it. Until then I will tell the unexperienced RVer to use caution.

C Nash

Senior Member
Grey and Black water tank maintenance

Thanks Kirk, I for one will continue to listen to your advice as I have found it to be correct most of the time and I can't say I agree with you all the time. Noticed you do not call anyone empty headed just because they don't agree with you on everything. Really hate to see name calling for anyone just posting their thoughts and opinions on a forum. :disapprove: Thought you asked a valid question and see no reason you should be blasted and called names. Not the place for those things and now I wonder about the method. I also agree that experienced and unexperienced RVer usr caution when trying any thing new. Mixing chemical in holding tanks can be very dangerous and even cause explosions but remember this is only my opinion with No scintific fact to back me up and no master degree in anything other than common sense.
POPPA now see what you started :laugh: :laugh:
Grey and Black water tank maintenance

Just a few notes for you science neophytes...

Sodium metaphosphate, is marketed as a packaged water softener (Calgon). The most commonly used is sodium hexametaphosphate (SHMP), which softens by sequestering. If you don't know, sequestration is a chemical reaction in which ions, of suitable charge, are bound into stable water-soluble compounds so that they are prevented from undergoing certain undesirable physiochemical reactions such as precipitation. As an example, the sequestration of iron to prevent it from oxidizing, precipitating, and staining.

Sodium hypochlorite (common household bleach) is indeed a base with a pH of approximately 11 in solutions sold commercially for such purposes. Bear in mind it is also an oxidant and thus can react with any number of other "common" household chemicals. From the MSDS for commercial sodium hypochlorite...


Hazardous Decomposition CHLORINE, OXYGEN

Note the materials to avoid...acids, ammonia and oxidizers. If you aren't aware, many common household products contain one or more of the above.

The point I would like to make...add any chemical judiciously and be very sure that you have ample ventilation when doing so. The decomposition of some of these "safe" household chemicals results in some rather nasty degradation products.

I'm not advocating either viewpoint, just trying to insure that everyone understands that there are hazards, often hidden, in dealing with even the most ordinary of household cleaners and detergents...

Oh, FYI...M. Sc. Chemistry, Lehigh University, Bethlehem, PA, 1999, B. Sc. Chemistry, East Carolina University, 1990. Pharmaceutical research and development for over 15 years. I do have some knowledge of the subject...


Senior Member
Grey and Black water tank maintenance

It's not all that bad Poppa, great topic and we all learned a great deal from it. Lots of experience on this board,
including yourself. Just wish I had Chelse P.H.D. in common sense. Cleaned the fence line on my pasture,now got a bad case of poison ivy. :dead: Speaking of hornets nest found some of them too.
Grey and Black water tank maintenance

Poppa, dont dispair. I took your advice and now have clean tanks with the sensors working. Before, nothing would do the job. In my book, results mean something so again, thanks for the info. :laugh:
Grey and Black water tank maintenance


Please stop following me around the internet from forum to forum. If you don't like The Geo Method the solution is simple; don't use it. People who try The Geo Method like it because it works and it's spreading rapidly through the RV community. Get over it.
Grey and Black water tank maintenance

I take no side as to right or wrong and don't really care. Lets lay this one to rest, ok guys. T-Jesus don't like uglies thanks.
Grey and Black water tank maintenance


The RV Eco-Kook Luddites absolutely hate The Geo Method with visceral passion. This isn't the first time I've been hounded over it, or the first poster who's done it. I've been putting up with this nonsnse since December 2003 when I first published it. That's why I created its own homepage. People can Google it now.


Senior Member
Grey and Black water tank maintenance


Please stop following me around the internet from forum to forum. If you don't like The Geo Method the solution is simple; don't use it. People who try The Geo Method like it because it works and it's spreading rapidly through the RV community. Get over it.


You are sure full of yourself! I have been around the forums for much longer than you and I don't waste time following some nut around. You should be so important. You are quite welcome to do anything you wish to your tanks, and if you use enough water you may even get lucky and never have a problem.
Grey and Black water tank maintenance

Hey Geometricenigma, I was just reading your Geo method and I like the whole concept! One question, or maybe two, lol. Does the water softner have to be powder and does the laundry detergent have to be powder? Is that what works best or would liqued work as well? We're getting ready to head to Canada this Monday and I can't wait to try this method. It sures makes a lot of sense. Plus if it will get rid of the odors I still smell even after using the 'so-called' best stuff for black tanks, I'll really be one happy camper! Thanks for the great information. I will let you know how it worked for us.

P.S. I've already been blasted by Kirk for posting pictures in the the Tips forum. He was extremely rude to me for no reason! He seems to be really grumpy because I know how to post pictures on my posts and I guess he doesn't. No reason to be rude though. I've only posted a few times, so from here on out I for one won't listen to anything he has to say!