How to Keep Your RV Holding Tanks From Freezing

October 14, 2021

How to keep your RV holding tanks from freezing image. Snowflake on blue background

How to Keep Your RV Holding Tanks from Freezing

 Key Points:

  • There are several areas on your RV that are susceptible to freezing: tanks, pipes, hook-up hoses
  • Location of your pipes and tanks has a lot to with potential freezing danger; know where yours are located so you can take proper precautions
  • There are low risk freeze prevention methods to help you enjoy your trip worry-free 

RVing is a great way to travel the whole year round, but RVing in the colder months or in colder climates can present you with some chilly, potentially frustrating problems. When temperatures drop outside, the contents of your holding tanks and pipes can freeze up, causing some costly and inconvenient problems. Thankfully there are some pretty simple and effective tools to use when camping in cold weather that will help you prevent the headaches that come with frozen holding tanks and pipes. In this guide we will be exploring your options for preventing freezing in your holding tanks or pipes. 


Areas Most Likely to Freeze

There are several spots on an RV that you really want to focus on insulating or taking steps to prevent freezing, both to prevent costly damage and to enjoy a continually functional water system while camping in colder temperatures.

  • Holding tanks
  • Pipes that are exposed to the outdoor temperatures
  • Water hook-up hose or sewer discharge line (when left hooked up)

Aside from keeping you yourself from freezing, these three areas are the most important things to insulate. The location of your tanks and pipes have a lot to do with the likelihood of freezing being an issue. The good news is that some RVs (often the case in Class B motor-homes or conversion vans) have the holding tanks sitting above floor level and the simple running of the built-in furnace, electric heater, or portable floor heater to warm the living space will help keep the tanks thawed. However, if your tanks are on the outside of your RV or closer to the ground (normally the case in Class As, Class Cs, Travel Trailers, and Fifth Wheels), they will be more susceptible to freezing. It’s important to know the location of your holding tanks because how you choose to insulate and heat your tanks and pipes will be guided by their location.

Tanks that are exposed to outside temperatures need some kind of insulation to keep them from freezing. Prolonged temperatures below freezing will eventually freeze a tank, either preventing you from dumping or preventing you from getting the fresh water you need. Again, tanks that sit above floor level, will likely be kept warm enough by the heaters within the living space, but tanks outside the living space will need something more.

Plumbing pipes can be located on the outside or on the inside of the RV. Pipes running along the interior of the living space will probably be fine because of the heat from the furnace or other electric heater. Pipes that are exposed to the cold outside air are much more likely to freeze without some kind of insulation or heat source to prevent it, so make sure you know where your pipes lie and provide adequate insulation because they will freeze much faster than a tank. You might end up dealing with costly damage if you just assume that the inside heater will do enough to keep the pipes ice-free.

You also want to be careful about leaving your water hook-up hose and sewer discharge line hooked up in below freezing temperatures. Water that pooled into the low points of the discharge pipe or water hose can easily freeze and create damage or dumping problems later. It might be safer to close the gray water valve, rinse the discharge pipe after a dump, shake it out a bit and stow it until you need to dump. You also may want to consider filling your freshwater tank and disconnecting the water hook-up hose if you know the temperatures will drop below freezing.


Options to Prevent Freezing

There is a lot of advice in the RVing community about ways to prevent freezing in your tanks and pipes while using your RV. Some of the advice out there is solid and some seems a little too risky for comfort. We will address both types of advice and lay out the benefits and the risks so you can decide for yourself what you are willing to try. The most effective and least risky options include:

  • Installing an RV skirt
  • Purchasing an aftermarket heating system or heating blanket
  • Purchasing a pipe heating cable
  • Keeping heavy rugs or foam board on the floor to trap heat inside
  • Continually adding RV antifreeze to your gray and black tanks
  • Reinforce sealants on windows and doors (if needed)
  • Window film and reflective foil coverings

It’s not necessarily vital that you adopt all of these options, but each will add another layer of assurance that freezing will not be an issue on your winter adventure. Let’s talk about some of these options in detail.


Install an RV skirt

The first option you have for keeping your holding tanks from freezing is to fully skirt your RV. RV skirting (also called windskirting) works best if you are staying in one spot for an extended period of time. Skirting an RV involves installing semi-permanent “walls” that extend all the way to the ground around the entire base of your RV. This skirting becomes a barrier to wind and cold temperatures drafting up through the floor and prevents heat from escaping through the bottom of the RV. By doing this, the ambient heat from the interior of your RV can actually help to warm the air under your RV, helping to keep your holding tanks thawed in cold conditions.

You have a few options when it comes to the material you choose for your RV skirt. But not all skirting options are created equal: 

  • Vinyl
    Many RVers believe vinyl skirting is easier to work with than plywood or insulation boards and is a much easier material to install and reinstall if you want to use skirting but will be relocating every few weeks. Not to mention vinyl lasts the longest of all the options, so you won’t need to replace it for a while. There are companies who professionally install vinyl skirting or you can purchase and install a vinyl skirting kit yourself if you’re on a budget.

  • Plywood and Insulation boards
    While plywood and insulation boards do provide an effective barrier from the cold temperatures, they are ultimately hard to cut, move, and store when you’re not using them. They cannot be folded and easily stored like vinyl when you need to relocate, which makes them effective but inconvenient. However, if you are camping in a location where you won’t be moving for several months, this might be a very effective, sturdy option.

  • Tarps
    Tarps are easier to remove and reinstall, but they rip easily and tend to not provide as much wind protection or insulation as a more solid solution, so you might be replacing these much more often than vinyl.

  • Foam boards
    Some campers choose to use foam boards to skirt their RV. This is a viable option, but make sure the material is strong enough to stand up against moisture and cold temperatures.

  • Straw or hay bales
    Many people choose to use straw or hay bales to skirt their mobile homes. Though effective, hay bales tend to be cumbersome and messy and attract mice and other small critters. And to be clear, hay is food for horses and other large animals, but straw is just bedding material. Hay will cost much more than straw, so keep this in mind when purchasing. Also know that straw bales can have terrible implications for allergies; some people don’t even know they’re allergic to straw until they get a big whiff of it, so use caution when choosing this option.

As you can see, RV skirting can provide an extremely effective solution to freezing holding tanks. But this is just one option of many; next we’ll examine aftermarket heating systems. 


Use aftermarket heating systems and heating cables

If you don’t want the hassle of installing an RV skirt and taking it down when you’re ready to relocate, you may want to consider using an RV holding tank heater or RV pipe heating system.

An RV tank heater blanket is simply a large electric blanket that can be installed on your black or gray water tanks. Depending on which blanket you choose, you can connect it to a 120-volt outlet or run it off the DC current. You can also purchase pipe heating cables that can be used on pipes that are exposed to the exterior temperatures or even the water hook-up hose if you want to stay on freshwater hook-up for the length of your stay. There is a specialized water hook-up hose you can purchase with a built-in heating element so you’ll never have to worry about freezing and won’t need to attach an aftermarket heating cable to the hose. The Camper FAQs website has a fantastic, very detailed article on how to use these aftermarket heaters and hoses. KOA.com also has a wonderful article on cold weather RVing and many different types of freeze prevention and cold weather preparation ideas.

A tank and pipe heating system provides an easy, all-encompassing solution to freezing holding tanks and pipes. Once installed, you will not have to worry about freezing issues, and you’ll be able to pick up and move your RV whenever and wherever you want without having to remove something like an RV skirt. But even if you choose to use an aftermarket heating system, skirting your RV can still be useful because it will help the heating system perform more efficiently by trapping the heat under the RV. In fact, RV skirting and aftermarket heating systems work very well in tandem, providing two-tier freeze protection for your RV.


Store your freshwater hook-up hose and sewer discharge line in freezing weather

If you are on water or sewer hook-ups and you have either a hose heater on the hook-up line or hose with a built-in heater, you shouldn’t have any problems leaving the hose hooked up to the water source or sewer port during freezing weather. However, if you do not have these heating items, you may consider filling your freshwater tank, closing your gray and black valves, and disconnecting and stowing the hook-up lines until you need to refill the freshwater tank again or dump the wastewater tanks. If you have no insulation or heating elements on these hoses, the residual water sitting in them can easily freeze, which can cause damage to your hose and your valve and make it impossible to get water or dump when you need to.


Insulate the RV floor

Just putting heavy rugs or foam board down on the floor of your RV will help stop heat from being sucked out through the underside and cold air from coming in through the floor. For pipes and tanks that reside above floor level, insulating the floor in the living area is a good place to start because it will help keep much of the heat from your furnace inside the camper. Plus your feet won’t get so cold when you have to make a midnight bathroom trip; win-win!


Use RV holding tank antifreeze

While you obviously can’t use antifreeze in your freshwater tank, you can certainly add it to your gray and blacks tanks often. This is another inexpensive and easy way to combat freezing dangers if you want to avoid costly heating systems and skirting. You just need to be sure that you are continually adding more to your tanks as you use them so the antifreeze doesn’t get too diluted; this also means you’ll need to have several gallons on hand depending on how long you’ll be cold-weather camping. However, because you are using your sink and shower drains constantly, antifreeze will not stay in the pipes to counteract freezing, so keep this in mind.

Be sure that you are specifically using RV holding tank antifreeze (propylene glycol) that will not damage the bacterial colonies in your wastewater holding tanks (if you are using a bacteria-based treatment like Unique RV Digest-It). Check the label to confirm that it does not contain bacteria-killing chemicals so that the waste breakdown process will not be hindered by your efforts to prevent freezing. And even if you aren’t using a bacteria-based holding tank treatment, it’s still better to use a propylene glycol based RV antifreeze over an ethanol-based antifreeze because propylene glycol is the safest option for humans and the environment. NEVER use automotive antifreeze (ethylene glycol) in your holding tanks; it is highly toxic to ingest, inhale, and come in physical contact with and it is designed for hearty engines, not plastic holding tanks.

Guide: Can I Use Antifreeze with Unique Products?


Reinforce sealants on windows and doors (if needed)

If you know you will be camping in very cold or below freezing temperatures, it’s a good idea to do a “camper health check” before you leave. One of the things to check for is the stoutness of the seals on your windows and doors. As you use your camper and especially when it gets hot and dry while camping in the summer months, rubber seals and weather stripping in your RV can become dried out and brittle. Weak seals will allow more cold air in; by ensuring warm air cannot escape through weak seals, the living space will remain warm using less energy and in turn any pipes or tanks that reside just under the floor or in the living space will remain thawed.


Install window film and reflective foil coverings

This is another good way to block cold from coming into the living space of your RV and stop warm air from leaving. You might be surprised how much warmth can leave through glass, even double-pane windows, so consider having some kind of window coverings with you in case the living space doesn’t get warm enough or if the worst should happen and a furnace or space heater fails.


Other Freezing Prevention Advice in the RVing Community

There are a lot of ideas thrown around on RVing blogs and forums, but some cross the line of acceptable risk in our opinion, and we want you to know what those risks are so that you can make your own assessment of whether or not you want to take that chance.

  • Do not let tank levels reach capacity or be nearly empty
  • While driving, leave your camper furnace on low
  • Use a space heater in the wet bay
  • Slowly run water through the lines and out the tanks overnight
  • Run a propane heater under the RV

Do not let tank levels reach capacity or be nearly empty

Proponents of this habit are operating based on the fact that small amounts of water freeze much faster while large amounts of water freeze slower. Because of this fact they recommend that you never leave your tank empty because small pools of water could freeze quickly, recommending you fill your wastewater holding tanks with some water after dumping and never let your freshwater tank get too low for the same reason. Conversely, they also recommend not letting your wastewater tanks reach capacity and to not fill your freshwater tank to the top; their reasoning here is that if the worst happens and it does freeze, the water has room to expand instead of having no room and damaging the tank.

We don’t believe filling and dumping your tanks to specific levels is the best solution for preventing freezing in tanks. Some of the recommendations we’ve already discussed like skirting and heating blankets are much more effective, less risky options and you don’t really have to think about it. With this tank level option, you have to be always checking your tank levels to make sure there’s either enough expansion room or enough liquid to not freeze too fast. Opt for spending a little money now on a heating blanket or high-quality skirting so you can enjoy your chilly trip instead of being hyper-alert about potential freezing.


While driving, leave your camper furnace on low

Campers who travel in freezing weather to their camping destination sometimes worry about potential freezing during the drive. One of the solutions to this situation shared in the RVing community is keeping your propane on and setting the interior camper furnace to a low setting. They say this will heat the inside of the camper en route, keeping tanks and pipes above freezing and even starting the warming process in the living space so you can feel comfortable when you finally reach your destination. However, having any sort of gas-driven heating element active in a moving trailer comes with a big fire risk. Obviously in a motorhome-style RV, you actually have access to the living space during the drive, so there will be a heater of some kind on, but it’s still not good practice to have any sort of heating source that requires a pilot light to be running while the rig is in motion. It’s also important to remember that a low-set interior heater will not warm tanks and pipes that sit below the floor level. It’s much safer and more effective to insulate exposed pipes and tanks with heating elements or foam during the drive.

The best options for preventing freezing during your drive is to just winterize the RV while on the road and then de-winterize it when you get to your campsite. This might be more trouble than you want to expend, which is why installing foam insulation on the pipes and heating blankets on the tanks might be the best choice while on the road.


Use a space heater in the wet bay

Not every RV has a wet bay, but for those who do, jeriandpenguin.com has an article on a solution to keep the whole bay warm using a space heater and a thermocube. A thermocube is a special outlet adapter that will only use power to turn on the heater or other device when the ambient temperature drops below 35 degrees and will only turn off when the temperature rises above 45 degrees. Using a thermocube to control the space heater in the wet bay will allow you to not have to turn it on and off all the time according to the temperatures because the thermocube senses it and does it for you. We have not closely studied this technique, so please weigh the risks for yourself and if you do try this, be sure to use a space heater that has high-quality safety precautions like sensors on the bottom to turn it off if it tips over.

Note: A thermocube is not necessary to use with tank heating blankets, heating cables, or heated hoses as they all tend to have their own temperature sensors that will regulate power and heat application.


Slowly run water through the lines and out the tanks overnight

Those who get behind this recommendation cite the fact that running water takes much longer to freeze, so opening some faucets to a sow trickle overnight makes sense. Some even recommend hook-up campers can keep gray and black valves just barely open so that wastewater can trickle to the sewer continually and not freeze. This solution sounds clever on paper, but there are several risks associated with this. The first and most obvious one is that you are wasting water. Even a slow trickle for eight hours or so will amount to more water than you might think, causing your freshwater supply to be lower the next morning and your wastewater tanks to be that much closer to needing a dump. There is also cost to consider; if you are on water hook-ups at a campsite, you might be charged for the amount of water you use (every site has different rules, so do your homework), in which case, this solution could be a more costly one than you think.

The other big risk is that if you are leaving your faucets and/or gray and black water valves slightly open throughout the night, there is the possibility that a slow trickle could cause what’s called an ice dam in the line, which could lead to that the slow trickle backing up behind the ice dam and have nowhere to go but backwards into the tank or living space. It’s a recipe for a flood into the living area of the RV, so be cautious with this option. We still recommend heating blankets and pipe insulation/heating cables over this option.


Run a propane heater under the RV

Running a propane heater under your RV comes with inherent fire and gas poisoning risks, so we would not recommend this option, but if it’s something you want to try, note that for this method to actually heat the tanks and pipes, you need to also have RV skirting installed to block the wind from blowing the heat away and instead trapping it under the RV. You also need to be sure the heater is clear of anything under the RV that could ignite and has proper ventilation so carbon monoxide gasses can’t invade your living space. An article from RVingKnowHow.com recommends all these precautions and also checking the setup throughout the night. Meaning in the middle of the night when we’re all supposed to be enjoying a healthy stint of REM? This solution sounds to us like more trouble and risk than it’s really worth, so we will say it again: opt for a heating blanket or heating cable for the pipes. It will save you worry and energy in the long run.


Review

Keeping RV holding tanks from freezing is necessary, but thankfully it isn’t a difficult task. In this guide, we have discussed many options for preventing freezing in your RV pipes and tanks. Here’s a short review of what we covered:

Areas most likely to freeze:

  • Holding tanks
  • Pipes that are exposed to the outside temperatures
  • Water hook-up hose or sewer discharge pipe (when left hooked up)

Recommended options for preventing freezing:

  • Installing an RV skirt
  • Purchasing an aftermarket heating system or heating blanket
  • Purchasing a pipe heating cable
  • Keeping heavy rugs or foam board on the floor to trap heat inside
  • Continually adding RV antifreeze to your gray and black tanks
  • Reinforce sealing on windows and doors (if needed)
  • Window film and reflective foil coverings

Other options for preventing freezing:

  • Do not let tank levels reach capacity or be nearly empty
  • While driving, leave your camper furnace on low
  • Use a space heater in the wet bay
  • Slowly run water through the lines and out the tanks overnight
  • Run a propane heater under the RV



Adopt The Unique Method

You bought your RV so you could enjoy life and spend time with family and friends. The last thing you want to do is waste precious time and money on fixing wastewater holding tank problems. Keeping your tanks in peak operating condition doesn’t have to be hard, confusing, or expensive if you follow our proven process: The Unique Method.

The Unique Method is a comprehensive tank care plan that we developed after years of conversations with real customers facing real problems. The Unique Method provides you with simple, preventative steps to stop odors, clogs, and sensor problems before they start so you can spend less time worrying about your holding tanks and more time enjoying the freedom and adventure of RVing. Try it yourself and see why thousands of campers trust their RVs with The Unique Method every day.

If you need more help with anything covered in this guide or simply have a comment, we’re here to help you anytime!

Contact Us




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