How to Deep Clean Your RV Holding Tank When Stationary for a Total Reset
Posted by Happy Campers Store on Jun 26th 2025
How to Deep Clean Your RV Holding Tank When Stationary: Start Fresh & Eliminate Odors for Good
If you're a full-time RVer who stays parked in one location, you're not alone in dealing with persistent tank odors — even when using a tank wand or trusted holding tank treatments.
If you’ve been parked in one spot for a while and are starting to notice stubborn odors coming from your RV, you’re not alone. One of the most common issues we see with stationary RVers is holding tank buildup—layers of waste and sludge that accumulate over time and don’t respond to standard treatments or even tank wands. Many RVers try to mask the smell by using odor-control products like Happy Campers or cycling through many different treatment brands, hoping something will work. But here’s the truth: no tank treatment can fight what’s hardened to the inside of your tank walls. To truly eliminate odor and restore your system, it’s time for a proper deep clean.
That stubborn smell? It’s likely due to sludge, scale, or bacterial buildup inside your black tank that regular flushing can't remove. Here's a proven, step-by-step guide to reset your tank and start fresh.
Why You Still Smell Odors – Even with Treatment
- Tank walls have layers of biofilm, grease, and scale
- Long-term stationary use means waste never fully flushes out
- Odor-causing bacteria hide under buildup where treatment can't reach
Until you remove that buildup, even the best treatments may only offer temporary relief.
Step 1: Pre-Treatment Flush
- Dump your black tank completely
- Add 5–10 gallons of clean water back into the tank via the toilet
- Use a tank wand or built-in backflush system to rinse and dislodge loose waste
Tip: Repeat this process 2–3 times if you're getting lots of debris out.
Step 2: DIY Deep Clean Tank Slurry no Treatments
Create a homemade tank-cleaning slurry using common and effective ingredients:
DIY Tank Reset Mix:
- 1 cup Calgon water softener (or any sodium-based softener)
- 1 cup unscented OxiClean (oxygen cleaner – dye & perfume free)
- Optional: 1/2 cup Dawn Platinum dish soap
- 5–10 gallons hot water
Mix and pour into the black tank. Let soak overnight (or 8+ hours). It's important tojust let it sit and soak if you are stationary.
Kleen Tank, a professional tank cleaning service, emphasizes that enzyme digesters only liquefy waste—often turning it into a thick, sticky sludge that clings even harder, can foul sensors, and encourages odor.
Step 3: Hydroflush Holding Tanks To Remove Buildup
How to Use the Valterra Hydroflush for Deep RV Tank Cleaning
This video from RVEducation101 does a fantastic job of showin you exactly how to perform the deep clean using the Valterra Hydroflush.
The Valterra F02-4100 Hydroflush is a powerful tool that lets you pressure-clean your black tank by injecting water directly into the sewer outlet. It includes a clear body for visual monitoring, a 45° elbow for smooth hose routing, and a built-in anti-siphon valve to protect your water supply.
Installation & Setup
- Connect to Your RV Drain Valve:
Remove your sewer hose from the black tank outlet and attach the Hydroflush by twisting it onto the bayonet fittings. - Attach Your Sewer Hose:
Connect the sewer hose to the other end of the Hydroflush unit. - Connect a Fresh Water Hose:
Attach a dedicated hose to the Hydroflush's water inlet. This hose will feed pressurized water into your tank.
Flushing Instructions
- Open the Black Tank Valve:
This allows waste and water to begin draining immediately. - Turn on the Water Supply:
Activate the connected hose. Water pressure will push through the Hydroflush and into the tank, helping dislodge stuck waste and paper. - Watch the Clear Adapter:
Use the transparent housing to monitor what’s being flushed out. Keep rinsing until the water runs mostly clear. - (Optional) Back-Flush:
Close the black tank valve for 30–60 seconds to let water pressure build inside. Then reopen the valve to release built-up waste with extra force. - Final Rinse:
Leave the valve open and water running briefly to ensure everything is clean before disconnecting the Hydroflush.
Why It Works
- Mechanical cleaning power removes buildup better than chemical or wand-only methods.
- Back-pressure flush breaks up stubborn clogs and tank wall residue.
- Clear visual indicator ensures you only stop flushing when the tank is truly clean.
Note: Always use a separate hose for flushing to prevent any contamination of your drinking water supply.
Product link: Valterra F02-4100 Hydroflush on Amazon
Step 4: Restart with Happy Campers
Now that your tank is clean, this is the perfect time to start fresh with Happy Campers holding tank treatment:
- Add the recommended dose of Happy Campers to your black tank
- Add 2-3 gallons of water (never treat dry tanks!)
- Use only Happy Campers – avoid mixing with bleach, or competing products
With a clean tank Happy Campers will neutralize odors before they start.
Long-Term Tips for Stationary RVers
- Using a regular treatment like Happy Campers will prevent buildup
- Use plenty of water per flush to avoid dry zones in the tank
- Dump your tank only when 2/3 or more full for proper flow
- Use a rotating tank wand monthly for ongoing maintenance
- Don't use Enzyme treatments
Enzyme treatments often convert waste and toilet paper into a thick slurry. This liquid can coat the tank walls and settle at the bottom, eventually hardening into a layer of residue if not flushed thoroughly and frequently. Source KleenTank
Stationary RVers are especially vulnerable:
If you’re parked for long stretches and not regularly flushing your tanks, enzymes won’t be enough to remove solid buildup that clings to the interior surfaces of the tank.
Final Thoughts
If Happy Campers doesn’t work right away, don’t give up — it just means your tank needs a true reset. Once you’ve removed the sludge and buildup, our formula will perform exactly as designed: odor-neutralizing, heat-stable, and septic-safe.
Ready to start fresh?