Most RVs spend a lot of time in storage. Whether you store your RV at home or at a facility, there are some things to consider regarding your holding tanks. 

Defining timelines of storage

First, let’s  define some terms: 

  • Short-term storage – By this, we mean the time in between camper uses during the camping season. This can be anywhere from a few days to several weeks.
  • Winter storage – This is the time from the end of the camping season to the start of the camping season the following year. 
  • Long-term storage – This is any amount of time longer than winter storage, from several months to many years.

RV storage with liquid in the holding tanks

RV control panel showing black tank is empty
Control panel showing black tank is empty

The most important thing to remember is to make sure that your RV’s holding tanks are empty when you put it into winter or long-term storage. This is true for all tanks – freshwater, gray water and black water. 

However, when it comes to short-term storage, as long as you store your RV where the weather will not drop below freezing, you can leave water in your black tank and deep clean the tank in between camping trips with a high-quality bacteria- and enzyme-based holding tank treatment such as Store-It. The reason for this is that you would not want the liquid to evaporate from the tank (or freeze if the temperature unexpectedly drops below freezing). This evaporation can lead to problems in your holding tanks, such as the growth of mold and unwanted bacteria, and clog formation, specifically in the black tank.

An RV compacted black water holding tank after water has evaporated from the tank
A compacted tank after water has evaporated from the tank

As the water evaporates it leaves behind all of the solid waste and toilet paper which, over time, will turn into a clog that we refer to as a compacted tank. (We discuss this type of clog and other clog types in this article.)

On the other hand, if you are expecting freezing temperatures, you do not want to leave water in the tank, because at below freezing, the bacteria and enzymes will become sluggish. There is also  a potential of the tank or plumbing cracking due to water expansion. Additionally, water deposits can be left behind when water is allowed to evaporate from holding tanks, which can lead to misreading sensors. 

Holding tank valve positions for RV storage

All three types of holding tanks on an RV have some form of drain with a valve. In the black and gray water tanks, there is a discharge valve that you open to dump the contents of the tanks.

RV freshwater holding tank valve in the closed position
Freshwater holding tank valve in the closed position

For the freshwater tank there is a low point drain, which can be opened to drain out any residual water that was not used during a camping trip. For short term storage of the RV, we recommend leaving all of the holding tank valves in the closed position, after all of the contents have been drained. Since they will be empty and presumably being used again in the near future, leaving the valves closed makes sense in order to keep any drips from happening while the RV is being stored. 

If you live in an area where it freezes during the winter time, then you will most likely be winterizing your RV for winter storage. (Check out this link to how to winterize your RV for winter storage.) 

Both the black and gray valves are closed as well as the discharge port capped for storage on an RV
Both the black and gray valves are closed as well as the discharge port capped for storage

We recommend leaving the black and gray water holding tank valves closed  because some antifreeze will inevitably make its way into the tanks, and you do not want this leaking out and onto the ground. As for the fresh water holding tank’s low point drain, leave this in the open position. Since there will be no antifreeze entering the fresh water holding tank, keeping the low point drain valve in the open position will allow for more air to circulate into and out of the tank. This can help prevent mold and bacteria growth in the tank. 

Sometimes you may need to store an RV for a longer period of time than winter storage, perhaps for several months or even years.

An RV in long-term storage withe the two gray tank valves and the black tank valve in the open position
An RV in long-term storage withe the two gray tank valves and the black tank valve in the open position

If you find yourself in this situation, we recommend storing your RV with completely empty tanks and leaving all of the holding tank valves in the open potion. This will allow air to flow into and out of the tanks, which can help prevent mold and unwanted bacteria from growing. For this long-term storage, it is a good idea to put a screen in place over the discharge ports and low drain point to keep insects and critters out of the RV tanks. 

Deep clean your gray and black water holding tanks before storing your RV

For both the black and gray water holding tanks, it is a good idea to deep clean them before winterization or long-term storage. (We go into the process for deep cleaning the black tank in this article and we go into the process for deep cleaning the gray tank in this article.)

A hand pouring Clean-It into an RV toilet to deep cleaning the black tank
Adding Clean-It to an RV black tank for deep cleaning

This deep cleaning is important to ensure mold and bacteria growth do not occur in the tanks while the RV is not being used. Also make sure that you thoroughly rinse the black and gray water holding tanks after the deep cleaning. Throughout the camping season, waste and toilet paper in the black tank, and food debris and grease in the gray tank can be left behind and build up. So although we highly recommend rinsing the black tank after every dump, we also recommend filling and dumping both the gray and black water holding tanks several times after a deep clean just before storage to ensure you get as much out of those tanks as possible. 

The takeaway

When preparing to put your RV into storage, it is important to make sure that the holding tanks are left completely empty. As mentioned before, the exception to this is when the RV is in short-term storage where temperatures will not drop below freezing and you are using the time to deep clean the black water holding tank with a product like Store-It.

RV discharge port with all of the valves in the closed position
RV discharge port with all of the valves in the closed position

On the whole, it is best to leave the black and gray water holding tank valves in the closed position unless you are planning on storing the RV for a long period of time, in which case you should leave the valves open to allow air flow. The freshwater low point drain may be left open while the RV is in storage to allow air to flow into and out of the tank. Finally, it is a good idea to deep clean and rinse your black and gray water holding tanks before putting the RV into storage to ensure that they are as clean as possible when you are ready to enjoy another adventure in your RV.

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