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16 Tips to Help Keep Your RV’s Gray Tank From Filling Up Too Fast

16 Tips to Help Keep Your RV’s Gray Tank From Filling Up Too Fast

Camping off the grid in remote locations, commonly known as boondocking, has been our favorite way to RV for more than 20 years. But the longer we want to stay in one place, the more we need to pay attention to our RV’s gray tank to avoid filling it up too fast.

Over the years, we’ve learned many ways to conserve water, allowing us to stay in our favorite camping spots for weeks instead of days. In this post, we’re sharing 16 tips for how we save RV gray water tank space when we’re off the grid.

16 Tips to Save RV Grey Water Tank Space

When you’re out boondocking for an extended period, one thing you’ve got to be mindful of is conserving the space in your RV gray water tank (or grey water tank, depending on what country you’re in). Nobody wants to break camp early just to dump it.

Over the years, we’ve gotten really good at conserving water, power, and space in our holding tanks to extend our stays as long as possible. But during our first 20 years of RVing, we were in a Class A motorhome, so we had more room in our tanks than smaller rigs.

For RVers with smaller holding tanks (including our new Outdoors RV 19MKS travel trailer), we’ve put together this list of ways to help keep your RV’s gray tank from filling up too fast. So, here are our best bathroom, kitchen, and general gray water tank conservation tips.

Most RVers know that the water from sinks and the (indoor) shower flows into the gray tank. For more info on the topic, check out our post “What is gray water?” And, of course, working to save RV gray water tank space also conserves fresh water. So even if your rig has a large ratio of gray-to-fresh-tank capacity (large gray tank in relation to the fresh tank), these tips will help extend your stay.


Here are six ways to conserve available space in your RV gray tank while you’re boondocking. Even if you don’t use them all, you’ll appreciate the extra camping time when you try even a few of these tips.

Take Navy Showers

A Navy shower is a water-saving technique originally used by sailors to conserve fresh water aboard ships (hence the name). To take a Navy shower, you get wet, turn off the water and soap up, then turn the water back on to rinse off, using as little water as possible.

We’ve gotten so good at taking Navy showers that we can each take a thorough shower in just a gallon or two of water. Of course, we’ve had help from a really good water-saving showerhead (see below).

Use Cleansing Wipes

While we shower every day, not everyone finds that necessary, especially when trying to conserve fresh water and the space in the gray tank. On days when you don’t get too dirty or sweaty and you’re okay skipping a regular shower, cleansing wipes come in handy as a way to wash up without using any water at all.

Simply Right Member's Mark Adult Wash-Cloths, 240 Count
  • Effective personal cleansing enhanced with lotion for skin health
  • Thicker wipe for gentle cleaning

Use a Water-Saving Shower Head

You can also save space in your RV gray tank by using a water-conserving showerhead with a shut-off valve. This lets you take a satisfying shower using a smaller volume of water, better control the flow, and easily turn the water off when you’re soaping up or washing your hair as noted in the “Navy shower” tip above.

You may have read our post about the best RV showerheads. These are popular with RVers for providing the feeling of a strong spray while still conserving water. There are several different types, but this is the awesome (and inexpensive) model we’ve been using for years. We love it for the satisfyingly firm spray, combined with very low water flow, AND the ability to control that flow.

Delta Faucet Single-Spray Shower Head, Chrome 52652-PK
  • INTENSELY POWERFUL. Immerse yourself in the steady, intensely powerful full body spray with forceful streams of water to satisfy all of your showering...
  • 2 CONVENIENT SPRAY OPTIONS. Shower head spray options include full body spray and pause

Capture Shower Water While Bringing It Up to Temperature

When you’re about to start your shower and run the water up to bring it to your desired temperature, don’t let that water run down the drain! If you do, it will contribute to filling the gray tank sooner than necessary, and will also reduce your supply of fresh water. That run-up water can be repurposed for other uses, preventing it from taking up valuable space/capacity in the gray tank.

We’ve always kept a 1-gallon plastic pitcher in our bathroom to collect that “run-up-to-temp” water which we then use to flush the toilet. You could also use the water to wash dishes or anything else you might need water for.

Rubbermaid Pitcher Classic 1 Gallon Clear Base, Red Lid
  • Capacity: 1 Gallon
  • Three-position lid that turns for free pouring, pouring with ice guard or closed

Shower Outdoors

To prevent adding water to your RV gray tank, you can use your outdoor shower providing it’s allowed where you’re camping (and assuming your RV has an outdoor shower). As always, make sure to use environmentally friendly biodegradable soap.

Dr. Bronner's - Pure-Castile Liquid Soap (Peppermint, 32 ounce, 2-Pack) - Made with Organic Oils, 18-in-1 Uses: Face, Body, Hair, Laundry, Pets and Dishes, Concentrated, Vegan, Non-GMO
  • MADE WITH ORGANIC OILS & CERTIFIED FAIR TRADE INGREDIENTS: Dr. Bronner's Pure-Castile Liquid Soaps are made with over 70% certified organic & fair...
  • ORGANIC & FAIR TRADE PALM KERNEL OIL: Grown by fairly-paid smallholder farmers in Ecuador to ensure sustainable harvesting techniques that won't...

Besides being biodegradable, we love Dr. Bronner’s for another reason — it lathers well but rinses off easily. That means less water is needed to rinse off after showering, saving even more fresh water and grey tank capacity.

You can learn more about outdoor showers in our posts, “Is an RV Outdoor Shower Worth Having?, and “Components of a DIY RV Outdoor Shower Kit.

Use an Astringent or Facial Cleanser

One very easy way to conserve the amount of water that flows into your gray tank is to use an astringent like witch hazel or a commercial facial cleanser instead of washing your face in the morning and/or evening.

Since our routine includes showering at night, we use the following type of facial cleanser on a round cotton pad each morning, adding zero water to the grey tank in the process.

Swisspers Premium Exfoliating Rounds, 2 Distinct Raised Textured Surface, Cotton Facial Pads, 80 Count Re-closable Bag
  • Dual-sided, one surface for exfoliation, one for more gentle use
  • Use the raised, textured surface to gently scrub away makeup and dull skin cells to reveal a smoother, brighter complexion

Use a Dry Shampoo

You can also use a dry shampoo on some days to save water, especially if you have longer, thicker hair (Peter does have an unfair water-saving advantage here). 😂

Not Your Mother's Dry Shampoo Clean Freak, 7 Oz
  • Spray generously on roots and throughout hair
  • Let product sit for 30-60 seconds


Following are five kitchen-related ways to help keep your gray water tank from filling up too fast.

Use Paper Plates & Cups

We generally try to avoid disposable single-use items like paper plates, however, we do trade some paper usage for water savings when we’re on extended boondocking trips. Using paper plates and cups when you’re boondocking means less dishwashing, saving both fresh water and gray tank capacity.

PRO TIP: Buy plates and cups that are all paper (no plastic), so you can use them to start your campfire, saving on water, gray tank space, and accumulation of trash.

Use a Catch Basin to Collect Dishwater

Use a catch basin (like a dishpan) to collect dishwater and toss it outside. Note that this is not a tip you can use everywhere, as some places prohibit the practice, and food particles can attract animals to your campsite. For more info, see our post “Can You Dump RV Gray Water On the Ground Legally?” Either way, we always use and recommend environmentally friendly biodegradable products.

MRS. MEYER'S CLEAN DAY Liquid Dish Soap, Biodegradable Formula, Lemon Verbena, 16 fl. oz - Pack of 3
  • This liquid Dish Soap cuts through grease, while making dishes clean and bright
  • Our Dish Soap has a biodegradable formula that contains plant-derived cleaning agents and other thoughtfully chosen ingredients to make grease...

Pre-Clean Dishware, Pots & Pans With Napkin

Using a paper napkin or paper towel to wipe excess food out of pots and pans (and regular plates if you use them) before washing is a good conservation tip for boondockers. Not only will you use less water and save gray tank space, but you’ll also be removing the food particles (as noted in the previous tip) so that if you’re disposing of dishwater outside, you’ll be reducing food odors that can attract wildlife.

Wash Dishes With Spray Bottle

Many campers, especially those who tent camp or have smaller rigs with smaller fresh and gray water tanks, prefer to wash dishes using a spray bottle containing a mix of water and white vinegar. You can pre-wipe any dishes with a napkin or paper towel (as mentioned above), spray with the cleaning solution, and then wipe with another paper towel, cleaning the dish or pan completely with virtually no water use.

Cook Meals on a Grill or Griddle or Using a Single Pot

Plan meals that you can grill, or cook on a camping griddle. You can also make one-pot meals or use a pie iron. All of these tips minimize the number of pots, pans, and utensils that need washing, thereby saving both fresh water and gray tank capacity.


Finally, here are four additional ways to save space in your RV’s gray tank while you’re boondocking.

Start Your Trip With a Completely Empty Tank

This should go without saying, but…. be sure to fully empty your gray tank (and black tank) before you head out to your boondocking spot, leaving the maximum amount of space possible. This will start you off on the right foot as you seek to conserve space in your holding tanks.

Install Low-Flow Aerators

You can install low-flow aerators in your faucets to reduce water use, which also means not filling up your RV gray tank as quickly. Different types, brands, and models are available and should work well for most RV faucets.

JQK Faucet Aerator, 1.5 GPM Flow Retrictor Insert Faucet Aerators Replacement Parts Bathroom 5 Pack, FAN15-P5
  • 【NOTE: Measure Dimension before Buying】 Aerator Dimensions: 21x21x12.2mm 0.83x0.83x0.48 Inch, please measure your original aerator dimension...
  • 【Smooth Flowing Faucet Aerator】1.5 gpm max at 60 psi (5.7L/min) 【TWO BONUSES】 M22 M24 washers & Plumber's Tape

Don’t Run Faucets Unnecessarily

This is something we should all be doing regardless of where we are, camping or not. Once you establish this habit as a boondocker attempting to conserve tank space and fresh water, you’ll find that even when you have an endless supply of water available, you’ll be more likely to avoid running your faucets unnecessarily.

Some examples of this would be while washing dishes, brushing your teeth, or even washing your hands. Every drop that runs down your drain is more water filling your gray water tank and less water in your freshwater tank.

Use a Blue Boy

A “Blue Boy” is a portable waste tank that some RVers carry to empty their gray (and/or black) tanks into. You can read the details about these totes in our post “3 Best Portable RV Dump Tanks (or Blue Boys).”

Just remember that you’ll need to have the space and weight capacity to carry a Blue Boy on your rig and a way to get it to a dump station once it’s full. Water weighs in at more than 8 pounds per gallon. Calculate accordingly to make sure you’ll be able to handle a full tank and that you can safely add that amount of weight to your RV.

Camco Rhino 36-Gallon Portable Camper / RV Tote Tank - Features Large Heavy-Duty No-Flat Wheels & Built-In Gate Valve - Removable Steel Tow Adapter, 3’ RV Sewer Hose & More RV Accessories (39006)
  • SIMPLIFY RV WASTE DISPOSAL: Make waste disposal hassle-free with Camco's portable waste tank. Easily transport waste from your RV black water tank to...
  • EFFORTLESS TRANSPORT: Haul your waste with ease with no-flat wheels built for any terrain, an oversized handle for easy maneuvering, & a steel tow...

Using some of all of these ideas should help you extend your boondocking trips pretty substantially. If you have any additional tips that you use to preserve the space in your RV’s gray tank, please share them in the comments below.

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PLEASE NOTE: We're handy RVers, not professional technicians. We're happy with the techniques and products we use, but be sure to confirm that all methods and materials you use are compatible with your equipment and abilities. Regardless of what we recommend, consult a professional if you're unsure about working on your RV. Any task you perform or product you purchase based on any information we provide is strictly at your own risk.

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