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RV Holding Tanks, and Tips That Save You Money and Time

Don has been an avid traveler and motorhome owner for most of his life and he shares his experiences along with valuable tips for RV owners.

A Typical RV Service Center.

This is a Typical RV Service Center which provides access to all of your Holding Tanks, and more.

This is a Typical RV Service Center which provides access to all of your Holding Tanks, and more.

Your Holding Tanks are Assets rather than Liabilities

Every RV owner quickly finds out that managing the Holding Tanks in their RV is one of the most important tasks they perform regularly if they want to have an enjoyable camping trip.

For RV owners, this part of the camping and traveling experience may be the most unpleasant, yet necessary, things that needs to be understood and more importantly, performed properly.

Read and follow these tips to make managing the contents of your holding tanks simple and easy tasks rather than problem areas.

Holding Tank Size and Content Weight

Over the years, I have owned 6 Motorhomes, two trailer campers and a fifth-wheel camper. Each of these, just like yours, had three holding tanks, each of which needs to be managed differently, and they are; a Fresh Water Tank, a Gray Water Tank and a Black Water Tank..

Even though each RV manufacturer uses different sizes of holding tanks in their RV’s, typically each is designed to hold the water and waste needs of a pair of people for a week or so, depending on the size of the RV and what they consider average water consumption and usage.

You see, water is heavy, in fact one gallon of water weighs around 8.34 pounds, For conversions of this number click here; Weight of Water.

The Fresh Water Tank

All of the RV’s we have owned in the past have had a Fresh Water holding tank that was often our source of water while on the road and when "dry camping"..

The Fresh Water tank is the traveling camper’s source of;

  • fresh water for drinking,
  • clean water for washing dishes,
  • water for the sinks when brushing your teeth, shaving, washing your hands etcetera,
  • even for your Ice Maker in your Fridge.

It is also the source of fresh water for your shower and it provides a small amount of water to help clean out your toilet with each flush.

Because of these needs, the Fresh Water Tank is usually the largest of your holding tanks.

For instance, in my 35-foot Fleetwood Bounder, my fresh water tank is capable of holding up to 85 gallons of water.

It only takes a quick calculation to realize that my 85 gallon Fresh Water tank can be holding over 700 pounds of water weight or from my perspective excess weight that causes your motorhome or towing vehicle to burn extra gas when it is traveling down the road.

So, the frugal RV owner will try to manage this water level, not only in the campsite but also when preparing to hit the road.

RV Sewer Hose Kit

The Gray Water Holding Tank

The second holding tank in your RV, by size, is usually the Gray Water holding tank.

The purpose of this tank in your RV to collect and hold the drainage from three sources;

  • the kitchen sink,
  • the bathroom sink
  • as well as for your shower/tub when you take a bath.

This “Gray Water” is dirty, but it is dirty with soaps, maybe a few food bits and just plain dirt. But this content isn't usually considered to be "sewage waste", so it can often handled a little differently from the contents of your Black Water tank.

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The Gray Water tank in my Bounder is capable of holding up to 58 gallons of this "non-sewage" waste water.

Again, making a quick calculation, and assuming that the Gray Water weighs the same as the fresh water, will show you that this tank of Gray Water can weigh up to 484 pounds.

Again, this is not weight that a traveler want to be hauling around in their RV.

RV Macerator Septic Dump Pump

The Black Water Tank

The third and really the most important holding tank for a camper to manage properly is the Black Water Tank.

Many people just don't want to talk about sewage waste, but in an RV, and actually in everyone's life, we all generate sewage waste that must be gotten rid of regularly.

This Black Water holding tank on my RV conveniently holds the waste from my toilet; that's it, toilet waste only.

And OK, you’re right, no one wants to deal with sewage, but as traveling campers who use our RV regularly, we need to manage this tanks contents properly.

At home your sewage goes down a pipe and disappears somewhere very conveniently across town where it is processed and disposed of properly.

But in the real world, specifically the world of camping, sewage requires some special handling. As a camper, you are more aware than most people of the need to regularly dispose of such a byproduct of life; so like you already know that do it properly and cleanly every time.

The Black Water Tank in my Bounder can hold up to 42 gallons of sewage waste. Once again, using the standard of 8 pounds per gallon, a full Waste Water tank can weigh as much as 350 pounds, or more.

Actually, considering the fact that there is a significant amount of solid waste in your tank, from used toilet paper to the "poop" itself; the weight of the sewage can be as much as another 50 pounds higher than if the tank held only water.

Bacterial Chemicals.

One thing you want to do with your Black Water Tank is to add the appropriate chemicals so that your sewage waste starts to break down more quickly and efficiently.

You see the contents of every septic tank grows its own bacteria and the sewage eventually breaks down, but at a slower pace than you will desire, considering you will be dumping your tanks possibly as often as weekly.

And almost as important, these chemicals will dramatically reduce the potential for sewage odors to rise up from the tank and into your RV cabin.

You can purchase these chemicals in most RV parts stores or you can order them online, if necessary.

Liquid Weight and being On the Road

If you add the three numbers I have mentioned in this article together; you will get a total of (700 + 484 + 350) or 1530 potential pounds (or more) of liquid weight that can be in the holding tanks of your RV.

Now, if you’re like me, you already cry every time you fill up the fuel tank in your RV.

Driving, or towing, a small house down the road is not a cheap proposition and fuel costs are a major concern when you are traveling any distance with your RV.

The typical RV does not get good fuel economy anyway, just from the total weight of the RV itself and all of its accessories and equipment that are part of living the RV lifestyle.

So, regardless of whether you get as low as 7-mpg (which is very typical with most older RVs) or maybe 10-mpg or 12-mpg (that you might get with a newer, smaller one), you are always looking for ways to make sure your RV is giving you the lowest fuel costs possible.

Liquid Weight Management Tips

You can see from these numbers that if you minimize this water and waste water weight, which can be as high as 1530 pounds, when you are on the road, you can have some effect on your RV fuel economy.

The following are some sound and useful tips on managing your holding tank contents, for the concerned RV owner to know and use when traveling in their RV.

Fresh Water

Of course, you want to have Fresh Water available in your RV at all times, but there are some smart things you can do that can save you money while on the road and camping.

Rough Camping

If you are going to be rough camping, in a state park or in the woods and there are no connections to fresh water at your intended campsite, then you should, of course, travel to your campsite with a full tank of Fresh Water.

Campground Camping

But, if you are only going to be traveling with maybe one overnight stay at a Rest Area or a Walmart or some other "dry campsite" with no connections, but will then be staying in campsite with full hookup the next day, you do have another option.

You can just fill your fresh water tank with maybe 8 or 20 gallons of fresh water. This will typically give you enough water for flushing your toilet, washing dishes, cooking and other tasks on an overnight stay. By doing this, you will not be traveling with the potential excess water weight of over 400 pounds of unneeded fresh water.

Gray Water

First of all, NEVER leave your holding tanks full of waste, even gray water waste, while your RV is in storage.

Even though Gray Water waste does not carry the levels of active bacteria in Black Water Waste, or have a very high level of solids content, you do not want these solids to congeal and solidify in the bottom of your tank, thus reducing your Gray Water storage capability over time.

You should especially not travel with a lot of extra weight from waste-water that can easily be dumped before you hit the road on a trip.

And, if you are going to be rough camping you want this waste tank totally empty.

Black Water

The rules for Black Water management while traveling is pretty much the same as with Gray Water, with a few exceptions.

First of all, never leave Black Water waste in your holding tank when you are going to store the RV for any length of time.

As mentioned, there can be quite a bit if solid waste in Black Water tanks and when this gets a chance to solidify. It can be a real task to soak into the resultant solid mass and eventually break it down to the point it can be flushed from the tank.

Shake it down the Road

In fact, because of this potential buildup of solid waste, I have a thing that I do on every trip. I always put at least 10 to 15 gallons of water into my Black Water tank before I hit the road, after it has been dumped.

This water will “slosh” around in the tank as I drive down the road; and in my mind, it is beating against any solids that may be in my tank. And hopefully, by the time you get to my next campground it will have broken down these solids down for me insuring that I keep my Black Water tank as empty of such buildup as possible.

Prep Empty Tank with Water

Always prep your Black Water tank with at least 2-3 gallons of water after it is emptied. You do this for two reasons; one is that you will also add your concentrated chemicals into your tanks with this water which does two thing; it helps prevent odors, and because these diluted chemicals will help the activated bacteria start breaking down the sewage in your holding tank.

Holding Tanks in summary

So, the smart RV owner will manage their holding tanks and their contents carefully, not just to save a buck, but so that everyone in the camper can have a much more pleasant trip without worrying about the world of water and waste.

And as you can see from this article, when you look at the weight of a gallon of water, and then at the size of the holding tanks in your RV, you want to come up with a plan that allows you to travel comfortable in your RV, but also do it with a minimal level of extra liquids in your Holding Tanks.

Use the Campground Facilities

Probably the most important thing what my wife and I do when we are camping is utilize the facilities of the campground itself, as much as possible.

Of course we use the showers in the campground bathhouse instead of the one in our camper. They are only a short walkaway and they are invariably clean, so why not?

Normally, during the day, and in good weather, we will both "Poop" in the bathhouse also. Again, its a matter of convenience and reducing the need to dump our tanks as much as possible.

A little pre-thought can save you from dumping too often and from from hauling too much excess liquids as you travel.

by Don Bobbitt, June, 2015

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This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.


Don Bobbitt (author) from Ruskin Florida on June 27, 2015:

MsDora- good to hear from you again.

And, I am glad that you like the information in my article. I feel that everyone who is interested in owning an RV one day should also know about the many special systems that are an integral part of an RV and how they affect the way a persons uses their RV efficiently.

Have a great day,


Dora Weithers from The Caribbean on June 26, 2015:

Thanks for the education on the water and sewage system in an RV. Never thought about it, but the knowledge is good to have. Voted Up and Useful.

Don Bobbitt (author) from Ruskin Florida on June 25, 2015:

billybuc- Thanks for the read anyway, my man!

'Tis the season for visitors, when you live in Florida, so we just had a couple leave and I am catching up on my backlog of reading myself.

One day away is OK, two, I can deal with, but more than that and I end up with "chair sores " on my butt, before I get back into my groove. LOL!

Have a great one.


Bill Holland from Olympia, WA on June 24, 2015:

This really doesn't apply to my life. I just wanted to stop by, say howdy, and wish you a great Wednesday.

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