How to get rid of stubborn RV odors

The most obvious culprit of odors in your RV is your black holding tank and toilet, so most RVers invest in a premium black tank deodorizer like Porta-Pak. But sometimes odors still linger, requiring odor control products that either work differently or target other odor sources. Walex is the global leader in odor control and offers a complete range of these types of products.

Odor Source: Grey Holding Tank
Product: Elemonate

An RV's grey holding tank is often overlooked as a potential odor source because it simply captures water from sinks and the shower. However, that water contains dirt, grease, and grime, which, over time, can form an organic sludge that breeds bacteria. Elemonate is a grey holding tank deodorizer that contains fresh lemon fragrance and natural enzymes that destroy build-up in the grey tank. Drop one Elemonate tablet in the sink and turn on the faucet for a few seconds to let it dissolve.

Odor source: Mildew, garbage, dirty laundry
Product: Odor Absorber

Tight spaces amplify foul odors, so keeping RV interiors smelling completely fresh is tricky. Odor Absorber is a gel product infused with a layer of charcoal that eradicates and absorbs odors. It keeps working for up to 60 days. Many RVers place one inside their garbage bin, under the sink, or around other potential odor sources.

Odor source: Black tank pyramid
Product: Commando

Sometimes, the reason for black holding tank odors is not a lack of deodorizer but a lack of water. Without enough water in the tank, solids pile up and get caked to the tank walls and sensors. This build-up creates residual odor and causes sensors to read incorrectly. Commando is a lightly-fragranced drop-in packet containing a powerful cleaning formula. Fill the tank with water and drop one packet in. The outer lining dissolves, releasing enzymes that attack and liquefy solids, cleaning the tank walls and sensors. Commando works without agitation in 12 to 24 hours (although you can leave it in longer).

Whatever the odor source, Walex has a product to eradicate it. Call 800-338-3155 or visit your local RV dealer for details.

How do I get rid of the black tank pyramid?

A black tank pyramid refers to the buildup of waste and paper in your RV's black holding tank, and it can put a significant damper on your RV travels. Waste buildup fills your RV with foul odors and is a pain to remove—without the right products. Here's how you can prevent a pyramid from forming or eliminate one if it does.

Don't leave your black tank valve open when you're hooked up at a site.

If you allow your tank to drain gradually, the liquids will pass through while the solids build up in a solid pyramid. To thoroughly dump the contents of your tank, you need the assistance of gravity. Keep the valve closed until the tank is 2/3 full, and then dump it. 

Use an enzyme-based deodorizer.

Enzymes digest waste and paper, so using a deodorizer with powerful enzymes will keep the contents of your black tank from solidifying. Walex's Bio-Pak is an enzyme-based formula contained in a rapid-dissolving water-soluble packet. When flushed down into the tank, the enzymes go to work immediately, breaking down buildup and deodorizing in the process. 

Use an enzyme-based black tank cleaner.

If you suspect a waste pyramid has formed in your black holding tank, you need to use Commando. Commando's innovative formula is packed with enough enzymes to restore your black holding tank to good-as-new, no scrubbing or agitation required. Not only will it liquefy the waste and paper, but it will clean tank walls and sensors, restoring the accuracy of your sensors. Here's how to use it:

  1. Empty your tank, rinse out any chemical residue, close your dump valve, drop one Commando packet into the toilet, and flush
  2. Then fill your holding above your highest sensor or completely full. 
  3. Leave it in for a minimum of 12 hours. Commando is formulated to work in as little as 12 to 24 hours for those in a hurry, but it will not hurt your tank to leave it in longer, several days, for more stubborn holding tank issues or clogs. 
  4. Empty your tank. Rinse again. You can now add your deodorizer, refill with 1.25 gallons of water for every 10 gallons of holding tank capacity and continue using the toilet.

You can use Commando to destroy existing buildup or preventatively every three months to control buildup from forming.

Happy adventuring!

Commando now available in recyclable packaging

After debuting recyclable packaging for Bio-Active Septic Tank Treatment in 2021, Walex is now packaging its black holding tank cleaner, Commando, in the same eco-friendly material.

Walex plans to transition several more of its RV/Marine product line to recyclable material in the coming years. The effort is part of an eco-friendly initiative extending to the product formulas; all of Walex's RV/Marine products comply with the country's most stringent environmental standards.

Recycle your Commando bag in a plastic bag recycling bin located at many retail stores, including Lidl, Target, Walmart, and Wegmans. To recycle, ensure the package is clean and dry before placing it in the bin.

The new recyclable bags are stamped with a seal from How2Recycle, an organization that aims to clarify the recycling process by standardizing instructions and labels. According to, the bag material can be made into synthetic lumber for decking, park benches, or recycled directly into another bag.

How long will my deodorizer last?

How often do you need to add deodorizer to keep your toilet odor-free?

We often get questions from RV owners about how often to use Porta-Pak or Bio-Pak, and how long one bag of the product will last. The short answer is this: two people living in an RV in a moderate climate will need to drop in one packet every five to seven days. Each Porta-Pak and Bio-Pak bag contains 10-packets, so the length of time one bag lasts depends on the number of people using the RV's facilities.

A good rule of thumb is to add a new packet of deodorizer right after you empty your tank. Always wait to empty your black holding tank until your sensors show that it's 2/3 full because gravity helps move all the solids out when you open the valve. Plus, if you're using a product like Bio-Pak, waiting long enough to empty will give the enzymes more time to liquefy the waste and paper.

Add enough water

After emptying the tank and adding your Walex drop-in, make sure to add enough water to disperse the active ingredients throughout the holding tank. The odor is less prevalent when the waste and paper sinks below the waterline. Otherwise, you may have a pyramid of waste and paper above the water line that causes malodor. We recommend starting with 1.25 gallons of water for every 10 gallons of holding tank. With adequate water added, one packet of deodorizer will control odor and treat waste up to a 40-gallons.

Keep your sensors functioning

One more thing to keep in mind: controlling holding tank odors depends heavily on watching your sensors, and if you start getting false sensor readings, you won't know when to empty and refill your tank. When this happens, you'll want to drop in one packet of Commando. This super-concentrated enzyme-based formula liquefies residual waste and paper build up within the tank, lubricates your valves, and cleans your sensors. Give Commando a minimum of 12-24 hours to do its job (longer is okay if it's a stubborn issue), and your tank will be good as new.

Happy Adventuring!

Will my RV holding tanks freeze?

How to prevent your RV holding tank and pipes from freezing

If you're spending the night in a cold climate—where the temperature will drop below 32 degrees—you might worry that your RV tanks and pipes will freeze. If you take a few precautions and understand the capabilities of your RV, you should be fine. Keep reading for helpful tips.

Keep your lines and valves warm.

The parts of your RV plumbing that are most vulnerable to freezing are the lines and valves rather than the holding tanks. In frigid temperatures, these can freeze and crack, causing costly repairs. In some RVs, the pipes are more exposed, while in other RVs, the propane furnace pumps heat around the tanks.

Drain the tanks and pipes and add RV antifreeze.

If the temperature drops down into the teens, you'll want to add RV antifreeze to the pipes to keep them from freezing and cracking. First, drain the tanks and lines to ensure nothing interferes with the action of the antifreeze. Then, dump a gallon of RV antifreeze down the sink and toilet drains.

RV antifreeze is very different from automotive antifreeze; the active ingredient is propylene glycol, which raises the freezing point of water. Propylene glycol is non-toxic. When temperatures rise, and you resume use of your holding tanks, you can also continue using holding tank deodorizers such as Bio-Pak or Porta-Pak.


Should I Get Porta-Pak or Bio-Pak?

Porta-Pak and Bio-Pak are both black holding tank deodorizers. However, the two formulas work differently to eliminate odors.

Porta-Pak gets rid of foul smells by completely stopping the growth of odor-causing bacteria. In contrast, Bio-Pak eliminates foul odors by digesting the odor-causing bacteria, waste, and paper in the tank. Bio-Pak's formula uses natural enzymes and is therefore 100% safe for septic systems and all campgrounds. Porta-Pak, on the other hand, provides better odor control in hotter climates.

Basically, which product is best for you depends on where you're dumping and your climate's temperature. If you're unsure which product to use, call us at 800-338-3155, and we'll be happy to help you.

Can I Use Commando in my Grey Holding Tank Too?

Commando is a black holding tank cleaner, but many customers wonder whether they can also use the product in their grey holding tank.

While Commando wasn’t designed explicitly for grey water holding tanks, customers used satisfactory results to clean their sensors. The same time frame of 12-24 hours or longer, if needed, is suggested. Simply drop a Commando into a plastic cup and dissolve with room temp tap water. Stir carefully and pour down the drain. A full tank will give you the best results. For Grey water tank sanitation and odor control, we make a product called Elemonate, designed explicitly formulated to destroy grey tank build-ups like organic sludge, grease, and food particles.

If you have any other questions about Commando or Elemonate, call us at 800-338-3155, and our RV and Marine sales manager will be happy to help you.

How often should I empty my RV’s black holding tank?

Living with a black holding tank is one of the less thrilling aspects of a long RV adventure. But caring for your black holding tank will help you avoid common issues like persistent odors, clogs, and false sensor readings. One of the most important things to know about your holding tank is when to empty it (although knowing where to empty it is also handy).

More frequent emptying is not necessarily better, and will actually probably worsen your holding tank issues. If you dump the tank often or keep it hooked up to the campground’s sewer system, the liquid waste will drain out, but the solids will remain. That’s how you end up with residual waste caked to your tank's sides, interfering with sensor readings.

Instead, wait until your holding tank is about 2/3 of the way full so that when you dump it, there’s adequate flow. With two people living in the RV, that shouldn’t be less than one week, but keep an eye on your sensors.

If you have a grey holding tank that also needs to be emptied, dump the black before the grey. The greywater, which comes from your sink and shower, will flush out any remaining solids in your hose.

After a while, you might notice your sensors not reading as well as they used to, or a residual odor emitting from your black tank. When this happens, you can always use a packet of deodorizer to deep clean everything. Commando contains powerful enzymes that break down solids and digest odor-causing bacteria. Just drop in a packet, add water, and wait about 12 hours. Your tank will be good as new.

Can I leave Commando in my tank for longer than 24 hours?

Some of the most common questions we receive have to do with how long to leave Commando in the black holding tank.

If you don’t leave it in the tank long enough, the enzymes won’t have time to work thoroughly, but people also worry about leaving it in for too long. The short answer is that you should aim to leave Commando in the tank for a minimum of 12 to 24 hours, but there’s no real harm in leaving it longer.

Commando is a pre-portioned product designed to work in as little as 12 to 24 hours for those in a hurry. However, if you need to leave Commando in your holding tank for 48 hours, 72 hours, or even a week, that would be okay and will not harm your holding tank. Each packet contains enzymes that immediately go to work, breaking down waste and paper and penetrating build-up on your tank walls and sensors.

Walex chemists designed the super-concentrated formula to work quickly to eliminate the most robust waste and paper build-up. Although it’s rare to have build-up after using Commando, when used according to instructions, if you continue to have issues due to extreme build-up, you can repeat the process.

If you have further questions about Commando or any other products, call us at 800-338-3155, and we’d be happy to help.