How often do you dump a black water tank?

In today’s guide, we will answer the following question: How often do you dump a black water tank? We will explain how to dump, clean and maintain the black water tank. 

How often do you dump a black water tank?

How often you should dump the black water tank is relative and depends on how much you use it. As a general rule, we could say that it is a good idea to think about unloading them when it reaches ¾ of the full tank, to avoid the urgency of unloading it anywhere, overflows and unpleasant odours.

There are level gauges that indicate the amount of water in each of the tanks, however, over time these sensors stop working well. This happens because dirt, trash or paper is stuck on them and they make an incorrect reading. Therefore, I recommend that you be aware of approximately how much water is in each one.

RV Make and ModelBlack Water Tank Capacity (gallons)How long it will last (for two people)
Winnebago Micro Minnie254-5 days
Keystone Bullet305-6 days
Winnebago Minnie254-5 days
Dutchmen Aspen Trail28-325-6 days
Jayco Jay Flight32.5-397-10 days

What is an RV’s black water tank?

An RV’s black water tank is also called a septic chamber, it is the tank that stores everything that is flushed down the toilet. It’s the tank that usually scares all new camper’s enthusiasts. 

The capacity will depend on the space you want to allocate depending on the number of people who use it and the autonomy days that they intend to be without unloading the tank.

Where to dump the black water tank of your RV?

Having a toilet with a discharge to a sewage tank means that sooner or later the moment of flushing will come. Crucial topic because you can’t do it anywhere or in any way. Hygiene and care for the environment go hand in hand on this topic.

Regarding the drainage of sewage from the motorhome, we are going to find many opinions and it is a very controversial issue. The main advice we can give you is that, ideally, the discharge is carried out at a point authorized for it, where there is water treatment. Some campsites or points have this service, but the reality is that when you are travelling, there is not always one at hand when we need to empty.

We recommend using common sense and do not discharge in populated areas for obvious reasons, but do so in remote rural areas where they cannot harm anyone and ideally away from natural waterways. For example in the middle of the road on the side of the road.

If you have a chemical or portable toilet, you can flush it in public restrooms or service stations (after consulting with the staff).

In the case of dry toilets, you can bury your solid waste since it is composted and spill the urine mixed with water since it works as a fertilizer due to its high concentration of salts.

How to discharge the black water tank of your RV?

Those who have sewage tanks, just pull a lever to open the lock valves and release their contents. There are those who have a remote control to perform this procedure from the inside and without having to get out of the vehicle.

On the other hand, if you have a chemical toilet, once you take the tank out of the bathroom for flushing, you must move the container tightly closed. If you are going to go to a public restroom or a service station, I recommend that it be at a low time, since the smell can be unbearable during the discharge. 

Lift the toilet seat. Have a container of water on hand for the first and second rinses. Remove the lid carefully and dump the remains trying to splash as little as possible, because the disintegrant is caustic, although I think this would be the least of the problems. Some have an angled weir and a valve that is depressed to let air in and debris doesn’t spurt out.

How to clean the black water tank?

I recommend that you do this procedure once the trip is over, before storing the vehicle and with the sewage tank empty.

Step 1: With the sewage tank empty and the shut-off valve closed, flush 1 cup of floor disinfectant liquid, 1 cup of baking soda, and a 5kg bag of ice through the toilet.

Step 2: Start the vehicle. The movement of the ice against the internal sides of the tank works as a brush that, complemented with the baking soda, will make it easier for the accumulated solids to come off. The disinfecting liquid for floors will leave you disinfected and smelling of perfume.

Maintenance of the RV’s tank systems

Tank systems have a certain amount of maintenance that you need to know to keep the system running smoothly.

The tank system must be emptied every winter to prevent the water inside from freezing and breaking the tank, which is generally made of aluminium. If you forget this step, you may run into a serious problem early in the season.

As a general rule, hot water tanks should not be interned with antifreeze, like the rest of your water installation, to prevent antifreeze from entering the hot water system, it is normal to have a set of by-pass valves.

Remember to close and open the two facets that make up the bypass completely, these systems do not work with the faucets partially open. It is very common to find yourself without hot water because you forgot to open the bypass at the beginning of the camping season. 

Leaving the bypass closed can cause the unit to overheat, if the heater is turned on without water in the tank, it can bring the metal in the tank to temperatures so high that it completely damages it.

Hard water can cause corrosion in a hot water tank. To avoid this, manufacturers place anodes in order to counteract galvanic corrosion of the metals from which the tank is made. Checking the anode is a task that should be done at least annually, although the time between checks should be shortened if you regularly camp in areas with very hard water.

The bottom line

Now that you know how much a black water tank can last, we recommend emptying, cleaning and disinfecting it as often as possible. Remember that full tanks can influence the way your caravan behaves, amplifying its movements. Whenever possible, travel with empty grey water and black water tanks.

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FAQ on How often do you dump a black water tank?

What is the procedure to treat sewage?

Wastewater treatment begins with the physical separation of large solids (garbage) from their current, using a system of grids (meshes), although such wastes can also be crushed by special equipment; subsequently, a grit is applied (separation of solids)

How to clean the clean water tank of an RV?

To clean the clean water tank of an RV, follow this guideline: to each litre of water, you must add 2 drops of 5% chlorine. If you do, your water will be much more drinkable and clean, eliminating the risk of acquiring different diseases. At we have many years of experience renting and improving your caravan.

Where to dump the sewage?

The sewage is poured directly into an aseptic tank or cassette. The tanks or cassettes that collect the sewage have a rotating tube through which they are discharged into the corresponding drain, and which must be connected to an aseptic pit or the sewer.


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