5 RV Grey Water Tank Maintenance Tips to Avoid Repairs
An RV has a grey water tank to hold sink and shower water. Regular cleaning prevents clogs and damage. Dump at RV stations for hygiene.
In many ways, an RV is much like a mobile home. It offers all the comforts of home, including modern conveniences like running water.
But have you ever wondered where all that water goes when it’s used? Well, that’s where the RV grey water tank comes into play.
An RV is equipped with at least three types of tanks – a fresh water tank, a black water tank, and a grey water tank.
The grey water tank is responsible for holding all the drained water from your sinks and showers until you’re ready to dump it.
Regular cleaning prevents the buildup of grease, soap, and other substances that can potentially cause blockages and damage your RV’s plumbing system.
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Understanding the Basics
What is an RV Grey Water Tank?
Sewer hose connecting RV holding tank to RV dump station hole” class=”wp-image-1886″/>A grey water tank is a crucial component of an RV’s plumbing system.
It serves the purpose of capturing and storing all liquid waste from your RV’s sinks and shower or tub drains.
The accumulated grey water remains in the tank until it can be appropriately dumped at an RV dump station.
Understanding how this tank functions can assist you in maintaining and managing it effectively.
Differentiating Between Black and Grey Water Tanks
Although both the black and grey water tanks serve similar purposes in an RV, they are used for different types of wastewater.
The black water tank is meant for holding sewage or toilet waste, while the grey water tank holds non-sewage wastewater from your sinks and showers.
Due to the nature of the waste they hold, these two tanks require different care and maintenance routines.
The Mechanics of RV Grey Water Tanks
Your RV’s plumbing system operates similarly to that of a regular home, but instead of the pipes leading to a municipal sewer system or a septic tank, they lead into either the black or grey water holding tank.
The grey water tank collects and stores all sink and shower drain water until it can be properly disposed of at an RV dump station using a specific grey water hose.
Cleaning Your RV Grey Water Tank
Regular cleaning of your RV grey water tank is not only necessary for proper function but also for the overall health and hygiene of your RV.
Left uncleaned, your grey water tank can start producing unpleasant odors and even become a breeding ground for harmful bacteria.
Using Chemical Treatments
While it’s generally not necessary to use dedicated products to clean your RV grey water tank, there may be situations where a stubborn blockage requires a more robust solution.
In such cases, you might consider using a tank cleaner specifically formulated to unclog holding tanks, such as the Unique brand of tank cleaner.
Employing Natural Cleaning Methods with Vinegar, Baking Soda, and Dish Soap

For most cleaning tasks, natural methods are often sufficient to keep your grey water tank in good shape.
One such method involves filling your tank with boiling water and dish soap, letting it sit for about 15 minutes, and then draining it.
Be sure to choose a dish soap that also de-greases, as this will help dissolve any greasy or soapy blockages in your tank or drain pipe.
Dumping Your RV Grey Water Tank
When it’s time to empty your grey water tank, there are certain best practices to keep in mind.
First, always ensure that the valve opening and closing of the grey water storage tank are working correctly.
This valve could be disconnected from the lever, or it might not be opening all the way, which could cause problems when trying to dump your tank.
When to Empty Your Tank
You’ll know it’s time to empty your grey water tank when the sink or shower starts backing up, the tank sensors show full, or you’ve used up most of your fresh water.
Keep in mind that the size of your tank will determine how long it takes to fill up.
How to Properly Drain Your Tank
To properly drain your grey water tank, first, secure the sewer hose to the tank outlet.
Open the grey tank valve and allow the wastewater to flow out.
Once the tank is empty, close the valve before disconnecting the sewer hose. Remember to wear gloves during this process for sanitation purposes.
Flushing Your Grey Water Tank
After emptying your grey water tank, it’s a good idea to flush it out with a mixture of bleach and water.
However, be mindful that bleach and rubber don’t mix well, so avoid letting this solution sit in your grey holding tank for too long.
Instead, run it through as you flush the system. This won’t likely cause damage and can help sanitize your grey tank.
Incorporating Ice into Your Cleaning Routine
Another handy trick for cleaning your grey water tank involves using ice cubes. Simply add a bag of ice cubes to the tank and drive around for a bit.
The ice will scrub the inside of the tank, dislodging any residue stuck to the walls.
Then, just drain the tank as usual, and you’ll have a clean, odor-free grey water tank.
Dealing with Potential Issues

Like any other component of your RV, the grey water tank can encounter issues.
These problems can range from a stuck air admittance valve, the buildup of food/grease/soap/hair causing blockages, to a disc left behind from construction blocking the drain.
Learning to identify and troubleshoot these problems can save you significant time, effort, and money in the long run.
Common FAQs about RV Grey Water Tanks
What is the Best Way To Clean a Grey Water Tank in an RV?
The best way to clean your RV grey water tank largely depends on the nature of the problem you’re dealing with.
For general cleaning, a simple flush with hot soapy water should do the trick.
If you’re dealing with stubborn blockages, you might need to use a specialized tank cleaner or employ the ice cube method for a more thorough scrub.
Can I Put Bleach in My Grey Water Tank?
Yes, you can use a solution of bleach and water to sanitize your grey water tank.
However, it’s crucial to remember not to let this solution sit in your tank for too long as bleach and rubber don’t mix well.
How Do You Deodorize a Grey Water Tank in an RV?
Regular cleaning is the best way to prevent odors in your grey water tank.
If your tank is already emitting unpleasant smells, consider flushing it with a bleach solution or using an RV tank deodorizer available at most camping supply stores.
How Do You Treat a GREY Tank in an RV?
Treating a grey water tank involves regular cleaning, prompt dumping when full, and occasional sanitizing.
It’s also important to avoid disposing of food particles, grease, and hair into your drains as these can lead to buildup and blockages inside the tank.
And there you have it – the ultimate guide to understanding, maintaining, and troubleshooting your RV grey water tank.
Remember, proper care and maintenance of your grey water tank are essential for enjoying a comfortable and hassle-free RV lifestyle.
Happy travels!
Frequently Asked Questions (FAQs)
What is considered grey water in an RV grey water tank?
Grey water in an RV grey water tank consists of wastewater collected from your shower, bathroom sink, and kitchen sink. Unlike black water, it does not contain toilet waste, but it carries soap residue, food particles, hair, and grease. These organic materials quickly settle to the bottom and create foul-smelling grease layers. Installing a simple mesh sink strainer catches food scraps before they enter the plumbing and decay.
What does routine RV grey water tank maintenance include?
Routine RV grey water tank maintenance includes flushing residue with clean water, lubricating valve seals, and adding enzymatic holding tank treatments. Monthly valve lubrication prevents rubber gate seals from drying out or sticking. Adding liquid enzyme treatments after dumping dissolves trapped grease and soap scum clinging to tank walls. Regular flushing also prevents tank sensor probes from getting coated, which prevents inaccurate monitor panel readings.
How do you flush an RV grey water tank using a reverse flush valve?
Connect a reverse flush valve attachment directly between your RV waste outlet and the sewer hose, then attach a non-potable garden hose to the side port. Close the black tank valve, open the grey tank valve, and run pressurized water into the tank for three to five minutes. Shut off the water supply and pull the attachment gate valve to dump the loosened debris. Repeat this cycle twice until the drain water runs completely clear.
How often should you flush an RV grey water tank during full-time camping?
Full-time campers should thoroughly flush the RV grey water tank at least once every two to four weeks. While daily dumping removes bulk liquids, grease and soap scum stick to tank floors and walls over time. Performing a dedicated rinse every two weeks prevents sludge buildup that causes valve sticking and tank sensor failures. Always dump your black tank first and your grey tank second so grey water rinses waste hose lines.
Is liquid or enzyme RV grey water tank treatment better for regular maintenance?
Enzyme RV grey water tank treatments are significantly better than chemical masking liquids for long-term maintenance. Living enzymes actively break down fats, grease, and hair without degrading plastic holding tanks or rubber gate seals. Chemical masking fluids only cover up odors temporarily with heavy perfumes and fail to dissolve settled grease deposits. For best results, pour four to eight ounces of liquid enzyme cleaner down the kitchen drain with two gallons of warm water.
How much does RV grey water tank replacement cost if cracked?
Replacing a cracked RV grey water tank typically costs between $500 and $1,500 for parts and professional labor. A replacement polyethylene tank alone generally costs $200 to $600 depending on gallon capacity and custom drain port locations. Professional RV service centers usually charge two to four hours of labor at $120 to $200 per hour to drop underbelly insulation and install new piping. Minor surface cracks can sometimes be repaired using an ABS patch kit for under $30.
Why does an RV grey water tank drain slowly even when the valve is fully open?
Slow drainage in an RV grey water tank usually indicates a clogged rooftop plumbing vent pipe, a grease obstruction, or a broken valve cable. A blocked roof vent creates negative air pressure inside the tank, preventing water from freely rushing out the drain port. Hair and solidified cooking grease can also form thick mats over the drain exit pipe. Clear the rooftop vent with a plumbing snake or flush the drain line with hot water to restore normal flow.
Is it legal to dump RV grey water on the ground while boondocking?
Dumping RV grey water directly onto the ground is illegal on most public lands, including Bureau of Land Management areas and National Parks. Federal regulations treat grey water as potential pollution because food waste, dish soap, and bacteria harm local wildlife and contaminate nearby waterways. A few designated areas permit surface discharge of sink water under strict local guidelines, but RVers should always assume surface dumping is prohibited. Always dispose of grey water at certified RV dump stations.