RV Sewer


Wastewater ends up in a holding tank tucked up under your RV. It comes in two varieties, black and gray, with each one having a separate tank.

Gray water is what comes out of your kitchen and bathroom sink. Black water is the other stuff. A smart boondocker recycles the gray water and then uses it to flush the toilet instead of their precious fresh water supply. In fact, there are special systems designed just for that purpose. For the weekend camper, a gallon milk jug of gray water tucked in behind the toilet serves the same purpose and it's free. By recycling, you save fresh water and you save space in your holding tank. If there's an ick factor, remember that all you did with the gray water was rinsing a few dishes or washing your hands.

Eventually, the tanks will be at capacity and it's time to head over to the dump station. Pull out your sewer hose and connect it to the tank with a twisting motion. The other end sits in the hole in the ground, pull the lever to open the valve and then wait for it all to drain. It doesn't have to be the messy job that some people seem to make it out to be. Yes, it's human waste but it's also a sealed system and the mess only happens if you're impatient. Check your hoses and fittings regularly to make sure the seals are still good and go together nice and tight. If you find one that looks like it might have hardened, try some Vaseline on the rubber and that will usually bring it back for a little while. If the seal has cracked then get rid of it and save some aggravation. You can buy them complete or by the piece and can replace every part of a sewer hose individually so it doesn't have to be expensive. I always carry a few spare seals for a quick repair as needed.

When it does come time to replace something, consider the clear plastic over the gray or black. Although it may not be something that you want to see, having the ability to glance down and see when there's nothing left will save you the aforementioned mess. Always drop your black tank first followed by the gray and by doing that, all the soapy water rushing through flushes your hose and fittings. Once you’re done, use the hose provided at the dump station to make sure everything’s extra clean and then go wash up. You'll see inexperienced people at dump stations make a huge production about putting on special gloves and fiddling with a very expensive looking hose. Wait a few minutes and along will come the RV veteran dragging out a cheap hose with their bare hands and finishing the job in less than half the time. Watch the spills, wash your hands and you'll find it effortless.

When it comes to maintaining your tank, watch what you flush but don’t be paranoid. There is absolutely no need to buy fancy RV toilet paper or holding tank additives so you can ignore all the dire warnings and save some money.  RV toilet paper is just Scott 1000 in disguise and is the same as you buy off the shelf for home use. Always (and I can’t preach this enough), always use Scott Single Ply or the equivalent in a store brand. You get used to it very quick and it won’t clog your black tank. The other brands may be nice to use but they will often cause havoc with your RV system. The old trick is to take a glass jar, fill it with water and drop in some paper. Give it a quick swirl and you’ll start to see the single ply break up and disintegrate before your eyes. That’s how you know it’s a good one to use. The heavier brands just sit there in the same way as they do in your tank. Come dump day that stuff will bunch up in the corner of your tank like the great big ball of wet, soggy paper that it is and no flushing in the world will shift it.

Holding tank additives are another way retailer’s separate people from their money. The RV section is full of them and every bottle tells a story of just how essential their product is. People that use these products defend that use by saying that their black tank has no odor and therefore it must be the product that is keeping down “the smell.” The simple truth is that a working RV sewer system should not smell because it is vented through a pipe that goes up to the roof of your RV.

If you do have an odor then that is the first thing to check. They have a plastic cap on top but it can get brittle with age and fall off allowing something to fall in there and cause a blockage. The pipe leading down to the tank can also crack from age. They are also prone to separation at the joints from the vibration of many miles on the road. If the pipe has a break then it will vent into the living area and continue to deteriorate with the movement of driving.

If the rig has been sitting for any length of time, an uncapped sewer vent, or any open pipe on the roof for that matter, can be attractive to nesting birds. Anytime there is an odor detected, make it a point to investigate the cause and repair the damage. There’s nothing fancy or expensive involved because the system is just regular PVC pipe and glue that you can find in any hardware store. I installed a Cyclone vent from Camco and it’s been fantastic, even dry camping in the desert with minimal water use.

The tank itself should be empty when you drop it and they have with a slight tilt in the direction of the outlet to facilitate the flow. The only reason the solid stuff should be caught up in there is because of that big ball of paper I mentioned earlier.  If you think you’re having a problem in your tank because a previous owner let the wrong paper build up or you just want to minimize any future problems then you can add a few cupfuls of water softener. You can find it in the laundry aisle and it helps to break up the paper. A day or two before you dump throw a little liquid laundry detergent into the mix and you’ll get a clean out better than any expensive RV product.

As a last resort for a stubborn clog, drain your tank then head to the nearest gas station and grab a few bags of ice, drop them down the tank through your toilet and then drive around for a while. The abrasive action of the ice sloshing back and forth will usually do the trick. Lastly, to prevent most of the aforementioned problems, don’t dump until you have to. This also means when you’re in a full hook up site at an RV park. If you hook up and have your valve left open, as many people seem to do, the liquid just flows straight out leaving everything else behind. That’s a guaranteed recipe for a clog caused by paper build up. You can hook your hose but leave the valve closed. Let it sit for a week or longer, then drop the tank and close it up again. You can leave the gray tank open all the time at a campground because it doesn’t have any of the issues that a black tank does.

If you’re in a primitive campground and not on hook ups but you that find your gray tank is filling too quickly, then it might be okay to release some out to water the grass but check first. Some places have rules that forbid it and others don’t. It’s not for hygiene purposes because it’s only dish and shower water but in state parks and places with sensitive vegetation, they worry about the dish soaps and shampoos leeching into the ground. Everything that I’ve read on the subject suggests that it’s probably a case of being overly cautious. One RV dropping a few gallons of gray water here and there is hardly on the scale of drilling for oil in a National Park but it does make sense and as a camper in wilderness areas, we need to practice the principal of carry in and carry out.

Occasionally you may come across a leak in the tank itself. They are thick plastic and built to be solid but cracks can happen especially in cold climates. Sometimes the mounting brackets rust out causing one side of the tank to drop away from the underside of the rig. Then of course there are road hazards like sharp objects thrown up or just plain operator error backing up over something that they shouldn’t. Whatever the cause, holding tanks sometimes need repair and it’s not something that should left for another day.

Many RV places will tell you that there is no way to repair a holding tank and that replacement is the only option. The tanks are usually high-density polyethylene plastic (HDPE) and yes, they can be difficult to repair. The glues advertised as suitable for plastic always have the disclaimer in the fine print that it will not work on polyethylene. A better way to repair a cracked tank is to weld the plastic. You can buy plastic welders on Amazon or at some of the bigger hardware/automotive stores. They are just a super-hot soldering iron that come with an assortment of plastic rods that work like glue sticks. Another option is to use a fiberglass patch from the hardware store. At auto parts stores, you can buy repair kits for gas tanks that can also be quite effective.

If you are really stuck and not too worried about the cosmetic appearance, then you can repair small holes with a heat source and the right kind of scrap plastic. For instance, even though they are thinner and a different color, milk jugs are the same material as most holding tanks. What you are looking for is the little symbol and letters that corresponds to the one embossed on your tank. You may have to go looking for it but it is on there somewhere. If you’re using a gas torch or anything with a flame, make sure no fuel or propane lines are nearby because on an RV, they can sometimes take indirect paths.

RV sewer systems are very straightforward and need very little maintenance. The trick is to make sure it vents properly and you’ll never have a problem. No chemicals needed!