RV toilets can easily get clogged, especially the black water holding tank. This can happen due to a number of reasons – improper toilet paper, foreign objects, waste buildup, etc. A clogged black tank prevents waste from properly draining out of the RV toilet and can cause nasty odors, leaks, and even toilet backup. Unclogging a black tank is an unpleasant but necessary task for RV owners. Here are some tips on how to unclog a black tank RV toilet.
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What causes black tank clogs?
There are a few common culprits when it comes to clogged RV black tanks:
- Using the wrong toilet paper – Regular household toilet paper breaks down too slowly and can easily accumulate in the tank. RV toilet paper is designed to dissolve rapidly.
- Flushing feminine products – Pads, tampons, and applicators should never be flushed as they do not break down.
- Flushing other trash – Paper towels, baby wipes, dental floss, condoms, and diapers can clog pipes.
- Dumping food waste – Grease, coffee grounds, and food scraps will stick to tank walls.
- Using too much toilet chemical – Chemicals like formaldehyde can react with waste and create solid deposits.
- Infrequent dumping – Allowing solid waste to accumulate for too long before dumping.
- Using the toilet improperly – Not enough water with flushing or aggressive plunging can damage pipes.
- Root invasion – Tree roots can break into tank pipes, especially with older RVs.
- Waste buildup – Naturally occurring deposits and sediment over time.
Blockages and clogs can occur in the tank itself, in the exit valve, or in the sewer outlet pipe leading outside the RV.
Signs of a clogged black tank
Watch for these common signs that indicate it’s time to unclog your RV black tank:
- Toilet backs up when flushing
- Toilet gurgles or bubbles
- Water pooling around tank outlet
- Sewage odors inside the RV
- Excess solid waste in tank after dumping
- Toilet drains slowly
- Toilet plugs up frequently
- Holding tank gauge reads inaccurately
- Sewage leaks underneath RV
The sooner a clogged black tank is addressed, the easier it will be to clear.
Preventing Black Tank Clogs
An ounce of prevention is worth a pound of cure when it comes to RV black tank clogs. Here are some tips to help avoid clogging in the first place:
Use the right toilet paper
Invest in RV-safe toilet paper that is designed to rapidly dissolve when wet. Look for brands marked as septic safe, marine safe, or RV safe. Never use regular toilet paper or paper towels.
Mind what goes down the toilet
Nothing but human waste and rapid-dissolving toilet paper should go into an RV toilet. No trash, feminine products, grease, or harsh chemicals.
Use a black tank treatment
Using a liquid holding tank deodorizer/treatment like Happy Campers or GeoMethod helps break down waste and keep tanks clean.
Clean tank sensors regularly
Sensors coated in grime can give false readings. Clean sensors allow you to accurately gauge when tanks need to be dumped.
Dump frequently
Don’t allow waste to accumulate. Dump tanks before they become overly full or when indicator lights advise.
Flush with water
Add extra water when flushing solids and before/after dumping to help rinse tank of lingering debris.
Inspect toilet seals
Check seals around the toilet base and valve annually and replace as needed to prevent leaks.
Use a backflow preventer
Installing a sewer backflow valve helps prevent sewage from backing up into tanks.
How to Unclog a Clogged Black Tank
If prevention fails and you find yourself with a clogged black tank, here are some DIY methods to clear the blockage:
1. Use a store-bought black tank cleaner
Tank cleaning products containing active enzymes and bacteria can help break down organic matter. Popular brands are GeoMethod, Happy Campers Holding Tank Treatment, Clear Black Waste Tank, and Tissue Digester.
To use, empty the black tank as much as possible. Then add the recommended amount of cleaner down the toilet. Fill tank with warm water and let sit for 6-12 hours or overnight before dumping again. Repeat as needed.
2. Try a DIY vinegar and baking soda treatment
For a homemade solution, dump and fill the black tank with fresh water. Pour in 1-2 cups of baking soda, followed by 1 cup of white vinegar. The chemical reaction will cause fizzing and foaming to help dissolve clogs. Let sit for several hours, then dump.
3. Use a tank wand to manually clean
A tank wand (or flusher wand) attaches to a garden hose and allows you to manually clean inner tank walls with a powerful spray of water. Insert the wand through the toilet and direct water in all directions to dislodge stuck-on debris.
4. Dislodge clogs with a drain snake
Feed a drain snake into the toilet and twist down into the tank pipes. Manually “roto-root” out stubborn clogs and waste buildup. Be gentle to avoid damaging pipes.
5. Remove and clean outlet valve
The black tank exit valve can get clogged too. Unscrew the valve from the outside of the RV, dislodge any debris, and reattach. Replace if necessary.
6. Flush with very hot water
Heat helps dissolve grease and waste. Fill tank with extremely hot water and let soak for a few hours before dumping. Caution: Don’t scald yourself!
7. Perform a pressure flush
Using a submersible pump and tank wand, pressurize the tank with a strong 20-30 gallons per minute flush for 2-3 minutes. Repeat 2-3 times to clear stubborn blockages.
When to Call a Professional
For severe clogs or persistent blockages that won’t budge, your best bet is to call in an RV repair technician. Professionals have specialized equipment to unclog blocked tanks, pipes, and valves. This includes:
- Hydrojetters – Powerful pressurized water jets
- Mechanical augers – Snakelike rotary tools to clear pipe obstructions
- Industrial strength drain cleaners
- Pressure flush systems
- Video pipe inspection
- Cutting tools to remove and replace damaged pipe sections
Technicians can also diagnose issues that might be causing chronic clogs, such as root invasion, collapsed pipes, loose joints, or a need for tank replacement. Don’t hesitate to call in a professional if needed – a few hundred dollars to thoroughly unclog and inspect your black tank system is money well spent compared to the cost of significant sewage-related repairs down the road.
Tips for Maintaining a Healthy Black Tank
Here are some general maintenance tips for keeping your RV black tank clog-free and working properly:
Dump regularly
Never allow tanks to become completely full. Dump early and often, especially before travel days. The RV tipping and sloshing from driving can also loosen clogs.
Rinse after dumping
Flush the tank with water to wash away any clinging particles after each dump.
Use water softeners
Hard water can leave scale on tank walls over time. Use filtered or distilled water in the RV. Or add water softener beads to the tank.
Try a tank de-icer
For RVs used in freezing climates, install an electric heating pad on tanks to prevent waste from freezing.
Add enzymes
Regularly using an enzyme-based tank treatment helps break down solids.
Clean sensors
Keep level sensors clean so you can accurately monitor tank levels and know when to dump.
Inspect seals
Check valve seals and gaskets yearly and replace worn ones to prevent leaks. Lubricate valves regularly.
Install a backflow valve
Sewer backflow valves prevent wastewater from flowing backwards into tanks if sewer pipes get clogged.
Black Tank Clog FAQs
Here are answers to some frequently asked questions about dealing with clogged RV black water tanks:
How can I unclog my RV toilet?
Start by using a plunger vigorously to try and dislodge clogs from the toilet bowl into the tank. Also try filling the bowl with very hot water and dish soap and flush repeatedly. For deeper clogs in the tank or pipes, use a drain snake or commercial RV tank cleaner. Avoid harsh chemicals that can damage plastic and rubber toilet parts.
What home remedy can I use to unclog my RV’s black tank?
For a natural unclogging solution, pour 1 cup of baking soda followed by 1 cup of vinegar down the toilet. Allow the fizzing reaction to work for at least an hour before flushing water through the tank. You can also mix your own black tank cleaner using dish soap, citric acid, and onion water strained through a cheesecloth.
Can clogged black water tanks repair themselves?
Unfortunately, clogs don’t resolve on their own. As more waste and paper accumulates, clogs can only get worse without intervention. Chemical additives may help marginally over time but won’t liquify significant blockages. It’s important to take action at the first signs of a clog.
How often should you empty RV black tanks?
Ideally black tanks should be dumped every 2-3 uses of the toilet or whenever the tank reaches 1/3 full. Allowing waste to accumulate causes clogs and odors. Never wait until tanks are completely full before dumping.
Why does my black tank drain slowly?
Slow drainage is an early warning sign of a brewing clog. Causes include waste buildup, improperly dissolved toilet paper, foreign objects, root invasion, collapsed piping, or a faulty valve. Correct any issues immediately before major blockages occur.
Conclusion
Dealing with a clogged black water tank is an inevitable hassle for most RV owners. Luckily, employing preventative maintenance steps can minimize the frequency. Periodically using tank cleaning treatments, dumping frequently, flushing with water, and protecting valves and seals goes a long way. When clogs do arise, starting with liquid chemical solutions or manual cleaning methods often does the trick. For severe or chronic issues, calling in a professional technician to comprehensively unclog and inspect your black tank system can give you peace of mind. With proper care, RV black tanks can enjoy smooth drainage for years on end.