Skip to content Skip to sidebar Skip to footer

Understanding RV Black and Gray Water Tanks

RV Black and Gray Water Tanks

Over half of your body is water, which means just about everything that goes on inside you depends on it. Like our bodies, one of the essentials elements of using an RV is managing how water comes in…and eventually goes out.

First, it’s important to understand that there are three types of water typical in most motorhomes: potable, black and gray

RV Black and Gray Water Tanks

RV Black and Gray Water Tanks Cont.

1. Potable Water is fresh, clean, drinkable water stored in your RVs potable water tank. It’s pumped through your RV’s potable water plumbing system to the places where you will use it, such as the shower, toilet, faucets and appliances.

2. Black Water is the wastewater or sewage from toilets. It likely contains a mixture of feces, urine, water and toilet paper…along with pathogens that must decompose before they can be safely released into the environment. Black water definitely earns its “scary” name, and it should be handled and disposed of with care and caution.

3. Gray Water is the wastewater that comes from sources other than toilets, such as sinks, showers, dishwashers, and washing machines. It’s typically free from fecal matter and contains fewer pathogens than black water. And it’s generally safer to handle and easier to dispose of. It can potentially be treated and reused for non-potable uses, such as irrigation for plants or lawns.

Most RVers don’t love dealing with black and gray water. It’s one of the most common complaints, with lots of horror stories you can Google or hear around the campfire. Once you know how to deal with these holding tanks, it’s really not that bad. Let’s delve into the details.

How do I check the status of my RVs Black and Gray Water holding tanks?

Most RVs have water holding tank sensors connected to an onboard monitoring system that tells you the status of how empty or full each water tank is. These gauges may be separate or integrated into a whole coach touchscreen control system. Either way, it’s important to know the size and capacity of each tank, and to regularly check the status of each. You can refer to your RVs Owner’s Manual or consult your dealer to find out what size tanks you have.

How accurate are the tank monitors?

Tank monitors are fairly accurate, assuming your tanks are free from debris. Once toilet paper or other debris is introduced into black and gray water tanks, those items can interfere with the tank sensors. You can flush the tank or clean out the tank with holding tank chemicals to resolve that problem. It’s good to know that a gray water tank that is full will start to back up and come out of the lowest drain in the RV…almost always the shower drain. And a full black water tank will back up into the toilet(s). Ideally, these are signs you don’t want to see but when/if you do, know it’s time to empty one or both tanks.

How often should I empty my BLACK WATER tank?

It depends on the usage within the RV. If it’s just you or yourself and one other person, you might be able to make the tanks last for a week or more. If you’re with guests or have a larger family, you may need to dump after a day or two. When possible, dump at an interval of at least a few days to a week, so there’s plenty of time for the solids to break down. Lots of RVers tend to empty their black water holding tank too often, which can mean that solid waste may be left behind because there is not enough water in the tank to break everything down. Also, full or mostly full tanks tend to help flush out the waste better. Gravity alone is great at helping give you a good, clean flush. Solid waste left behind can get caked on the inside of the tank and interfere with the tank’s sensors. And in cold weather, small amounts of wastewater are more likely to freeze, which you definitely don’t want. It is best to wait until the holding tank is at least two-thirds full before you flush it.

How do I dump my RV’s holding tanks?

1. When it comes to black water, ONLY USE AN RV DUMP STATION to empty this tank. It’s dangerous and typically illegal to dump black water anywhere else. Remember, black water is filled with dangerous bacteria that can spread disease and contaminate the environment.

2. Always dump the black water tank first, then the gray water tank. This takes advantage of using the gray water tank to help flush out the sewer house and help clear any solids or items that might get stuck while dumping.

3. Connect one end of an RV sewer hose to your wastewater outlet on the exterior of your RV, ensuring it’s a snug fit, and connect or place the other end of the hose securely into the RV dump station sewage receptacle. In some instances, you may want to have someone ensure and monitor that the hose doesn’t come loose at the outlet end.

4. Once both ends are connected, you can open the black tank valve. Once you hear the black tank’s flow trickle to a stop, you can then release the gray tank valve.

5. When both tanks are completely empty, close both valves. You never want to leave the valves open, even if you’re connected to a sewer at a campsite or other location as it’s a great way to form a clog, allowing the wastewater to flow through, but not the solids and debris, which can then accumulate. Again, you want to build up each tanks volume to ensure a thorough dumping next time.

6. After you’ve dumped both the black and gray tanks, thoroughly flush out both tanks. Some RVs have a built-in flushing system, but if yours does not, there are tank cleaning supplies and chemicals that you can purchase at your dealer and use.

Can I dump my GRAY WATER tank while boondocking or dry camping?

This is not recommended due to the pathogens typically in gray water, which can contaminate the environment. But there are some safe practices for alternative gray water dumping that you can investigate through a proper Google search.

How do I clean my BLACK or GRAY water holding tanks?

You’ll want to keep your black and gray water holding tanks odor free and clean. Always use a black water tank deodorizing and cleaning chemical. It helps break down solid waste and keep your toilet(s) from smelling bad. Flush a dose of the chemical along with an amount of water as indicated into the toilet every time you empty your black water tank. The chemicals come in both powder and liquid forms.

There are gray water tank odor control chemicals as well, but you may not need to use them as often since gray water doesn’t always have the definite odors that black water has.

Using tank cleaning chemicals regularly helps ensure you don’t get clogs.

8 Tips for Van Life Storage and Organization

RV Black and Gray Water Tanks  What do I do if I get a clog in my BLACK or GRAY water holding tanks?

First, don’t panic. Every RVer knows they need to be prepared for potential hiccups because they could happen at any time, especially when its most inconvenient. A few good solutions for black water and toilet clogs include:

1. For toilet clogs, own a flexible toilet tank wand. This device includes a power nozzle that can connect to your faucet with a flexible hose. You insert the wand into the toilet bowl and down toward the tank for a high-pressure spray that can help break up the clog.

2. Open the toilet valve and pour several pots of boiling water down the toilet into the tank. Let the water sit overnight and soak. And then you drive a bit to mix it all up.

3. Use a septic-safe de-clogging chemical. These are toilet tissue paper “digesters” and other chemicals that you let sit in the toilet and tank for several hours.

4. Use the “Ice Cube Method”. Fill the toilet basin to 1/3 full of water. Add ice and fill the rest of the toilet. Flush the ice down the toilet and drive around. Keep flushing with lots of water. If you’re lucky…it’s a fix.

How do I prevent clogs in my RV toilet and black water tank?

– Use only RV-safe or septic-safe toilet paper. Use 1- or 2-ply tissue that breaks down fast. It’s sold at RV dealers and camping supply stores, as well as other retailers.

– Flush more often. You might want to flush twice for every use. You can also add water through your toilet into your tank periodically to break up potential clogs before they happen.

– Use less toilet paper. Cut back on the volume of paper you use.

– Use a two-step flush: push the handle or pedal halfway down to fill the toilet bowl with water, then push it down all the way to flush into the holding tank.

– Don’t throw trash into your toilet. It won’t break down in your holding tank.

– Make sure you are regularly adding the black water tank cleaning chemicals recommended for use after each tank dump.

Though we think that about covers your RV Black and Gray Water Tanks, if you have any further questions about navigating your black or gray water tanks, leave us a comment below and we’ll be sure to address your questions!