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RV Plumbing Tips for Newbies: Keep RV Holding Tanks Working

Stephanie, her hubby, and their two cats enjoy living and traveling full-time in their RV, often camping off-grid to stretch their budget.

Camping in Florida

Camping in Florida

How Does RV Plumbing Work?

RVing is wonderful, but only if your plumbing is working smoothly! One aspect of RVing that is not delightful is dealing with the RV sewage and waste water holding tanks.

Every RVer, from the couple in the million-dollar Prevost to the guy or gal in the 20-year-old Winnebago, has to put on their rubber gloves and regularly get down to the unpleasant business of emptying their waste water holding tanks. However, with proper care and maintenance, all systems will work easily with minimal hassle.

If you're new to RVing, caring for and maintaining your RV holding tanks may seem like a complicated and overwhelming undertaking. It really isn't that complicated, but there are some things that every RV owner should know. Here are some tips for keeping your systems flowing smoothly.

All About RV Holding Tanks—Which Tank Holds What

Most motor homes and travel trailers (except very small trailers and pop-up campers) have three tanks as part of their water and waste systems:

The Fresh Water Tank

  • Provides water for washing dishes, showers, and flushing the toilet. Some people use water from their fresh water tanks for drinking, others prefer to buy bottled water. The fresh water tank is filled using a clean hose, one reserved for use with drinking water, which is connected to safe drinking water from a city water system or a well. Generally, a white hose is used exclusively for this purpose and is stored separately from other hoses so that it doesn’t become contaminated.

The Gray Water Tank

  • Is used to collect used kitchen and bathwater and store it until it can be dumped safely into a dump station or campground septic system.

The Black Water Tank

  • Stores used toilet water and waste until it can be safely dumped at a designated dump station or campground septic system.

One of the first things every RVer must learn is how to deal with these tanks. Filling the fresh water tank is easy as it’s just a matter of hooking the white hose up to city water and filling the tank. Emptying and maintaining the black and gray water tanks is somewhat more complicated. Your RV manuals will give you specifics on how to hook up your sewer lines to the dump station and how to dump your tanks. However, just as important as dumping is learning how to keep your system smooth-flowing and clog-free.

Mishaps Emptying Holding Tanks—Only Funny in the Movies

Anyone who has seen Robin Williams in the movie RV has seen the worst-case scenario about dealing with waste from the RV tanks. The movie had me rolling in the aisles, as the sewer hose came loose spraying everyone in the area with the waste from the tanks, but at the same time it hit too close to home – my RV home!

Although the movie exaggerated the problems of dumping, the scene where other campers gathered around to watch, comment, and give advice was not so far-fetched. New RVers will quickly find out that their problems are a spectator sport for the rest of the campers. The minute your campground neighbors get wind of the fact that you are having a problem with your RV, they’ll quickly congregate around you to help, watch, comment, and give advice- whether you want them to or not.

Although it can be embarrassing to be the center of attention as you demonstrate your ignorance of how things work on your RV, you’ll usually find other RVers helpful and knowledgeable. Let them help you out when you need it.

How to Know if Toilet Paper Is Safe for RV Holding Tanks

Use the proper toilet paper for RV waste water tanks. Although it isn’t necessary to purchase expensive toilet paper in an RV supply store, it’s important to use toilet paper that will disintegrate easily in water. We use Scott’s Safe for Septic paper which can be purchased in discount stores. If you’re unsure about the safety of the toilet paper in your system, do this little test: fill a small jar with water and place a sheet of toilet paper in it. Cover the jar and shake it for a half minute. If the toilet paper disintegrates easily, it will be safe to use in your tank.

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RV Dump Stations and Dump Station Tips

For those who dry camp or boondock in areas that do not have dump stations, RV Dumps is a good resource to help you locate dump stations along your route. This site also has some good tips on how to dump and dump station etiquette.

Maintenance Tips

Keeping tanks working properly is a lot easier than fixing them. Here are a few tips that will help keep your black and gray water tanks in good working order:

  • Add water to the tank. Always put a gallon or two of water into your black water tank after emptying. Then add tank chemical (usually 4 oz. of liquid chemical per 40 gallons of water that the tank will hold) by pouring it carefully into the toilet and flushing it down. There are several brands on the market. We use RV Toilet Treatment – TST made by Camco. Whatever chemical you decide to use, be sure to use one specifically made for RV tanks and use as directed. The TST will help break down solids and help keep your tank from smelling bad. Don’t skip it! If you are in a very hot climate, you may want to add more chemicals after a few days.
  • Flush with enough water. Use enough water to flush thoroughly. Although it's tempting to try to conserve water, too little water will cause toilet tissue and solids to adhere to the lines rather than fall into the tank. This will eventually cause a buildup of solids and prevent the tank from emptying properly when you dump.
  • Use RV-safe toilet tissue only. NEVER flush down tissues, paper towels, or anything other than RV-safe toilet tissue (see below on how to identify RV septic safe toilet tissue.)
  • Only dump when tanks are nearly full. When parking at a campground, hook up your sewer line if you wish, but don’t open the valves to dump until your tank is at least two-thirds full. This will ensure that the weight of the collected wastewater pushes everything through the lines rather than building up a little at a time and causing a clog. Keeping the valves closed until you are ready to dump will also keep the smells of the sewer system from drifting up into your RV.
  • Dump black tanks, then gray tanks. When dumping your tanks, always dump the black water tank first, then the gray water. The soapy gray water will help to rinse out your hoses. Flush through some clean water to rinse the residue out of tanks and hoses, but be sure all rinse water goes into the campground sewer connection. Never rinse hoses and let water flow onto the ground around the tank.
  • Check tank levels. After dumping, you’ll probably want to check your tank gauges to be sure the tanks have emptied properly. Unfortunately, the wastewater tank gauges are notorious for showing inaccurate readings because sensors are usually inside the tanks and can easily gather bits of toilet tissue or residue that will give a false reading. If you suspect that you are not getting an accurate reading, you can double-check the condition of your black water tank by turning off the water pump, opening the flush valve in the toilet, and looking into the tank with a flashlight. (Hang onto that flashlight!)
  • Ice cube trick. This is a trick that some RVers use to loosen a stubborn build-up that’s deposited on the bottom of the black water tank. Add several gallons of water to the tank and dump in a bag of ice cubes. Take your rig for a drive of 5 or 10 miles. The ice cubes bouncing around in the tank will help loosen any buildup and you’ll be able to dump the residue easily.
  • Wear rubber gloves when dumping and avoid touching the outside of the gloves. Rinse off before storing.
  • Carry an extra garden hose for rinsing the outside of the sewer hose and the dump station area. Store this hose separately from the clean water hose and never let the two come in contact with each other. Often the water provided for rinsing at the dump station is not potable water. Never fill your fresh water tanks with any water that is not marked "potable" or "safe for drinking" water.
Camping in Alamagordos, New Mexico

Camping in Alamagordos, New Mexico

Life Is Good When the Plumbing Works!

Life is good when the plumbing is working smoothly! No matter where you are - in a house, office, or RV, when the plumbing system breaks down, it can cause misery and headaches. Keep your RV plumbing systems running smoothly by following the common sense tips above and your manufacturer's instructions for dumping.

Remember: Never Dump Gray or Black Water on the Ground!

It will contaminate the area and may find its way into local drinking water. Have respect for the environment and for the people who follow you by always using proper procedures for disposing of your gray and black wastewater.

Now, quit thinking about sewage and hit the road!

Happy Trails!

RVing Articles

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: I’m only using my fifth wheel 8 to 10 days a month. Is it okay to leave the black tank for three weeks at a time?

Answer: It's not a problem to leave the tank sit as long as you have plenty of liquid in it. If you don't use it much, you might want to add a few couple of gallons of water and some extra tank chemical to it when you plan to let it sit, especially in hot weather.

Question: How effective are these advertised "macerators" that help assist with eliminating larger particles in RV holding tanks?

Answer: As far as I know, they work just fine. However, unless you are planning to camp off-the-grid and pump waste into a large holding tank mounted on a truck bed, it probably isn't necessary. You would probably not need a macerator if you intend to dispose of waste into a dump station or even into a "blue boy" that's on the ground. We know a lot of RV'ers and the only person I've heard of who uses one was pumping waste for a long distance into a home sewage system.

© 2011 Stephanie Henkel

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