Interesting RV Articles AC Power RV Chalet RV Maintenance, Service and Repair A Safe LP System RVs, Rubber Roofing, and You RV Waste Systems (for April 2000 RV View) By Gary Bunzer Take a poll at any RV campground or rally and I would wager that a clear majority would agree that the least enjoyable task associated with the RV lifestyle is evacuating and cleaning the RV waste holding tanks. I would then choose not to ask those in the minority what they were thinking could actually be worse! As distasteful as it may be, a necessity it truly is - especially for the conscientious RVer who cares about his rig, his RVing neighbors and the environment. Background Since the advent of grey water holding tanks and the refinement of true RV self-containment some thirty years ago, RVers have simply taken for granted the convenience of using on-board fresh water for cooking, drinking, washing, bathing and toilet use. A natural and secondary aspect of that convenience is that it now must be considered how to unobtrusively collect, store and get rid of all liquid and solid wastes during a RV excursion. A quick refresher reveals there are two distinct types of RV waste systems: the "grey" system and the "black" system. The grey system is typically waste from the kitchen sink, the lavatory sink, and the shower or tub. Basically it refers to the liquid waste. The black waste system is the solid waste associated with the toilet. The black and grey systems should not be inter-connected, that is, they must each have a dedicated method of storing the waste in holding tanks and each must have its own waste termination or dump valve. There are, however, a few exceptions to this rule. For instance, in some cases it is permissible to have one other fixture drain into the black water tank. For all practical purposes, however, the two systems should remain separate. Most holding tanks are mounted below the floor level. Some tanks are sandwiched between the upper floor and a sub-floor; still others may be located between the floor and a belly pan on those units with sealed bottoms such as the popular "basement" models. The coach construction and the layout of the floorplan are two of the determining factors as to where the holding tanks are to be situated. The black tank, however, is typically positioned directly under the toilet. Additionally, all holding tanks must be removable. That is, other components such as floors, sub-floors, undercarriage trailer hitch receivers, or any aftermarket add-on device must permit the removal of the holding tanks for repair or replacement. Old Paradigms Ask any six RVers how they utilize the holding tank systems and you just may find six different versions to the same story. By and large though, many RVers were schooled to leave the grey holding tank valve open while connected to the sewer at the campsite so liquid waste can simply exit the tank automatically, thereby eliminating the need for numerous trips outside to dump each tankfull. This became especially popular since the campground provides a more plentiful source of fresh water than is available from the on-board fresh water tank. In contrast, RVers usually leave the toilet tank termination valve closed while connected in the campground and evacuate when that tank is almost full. The reasoning behind this standard is that it takes longer to fill the black tank with solid waste than it does to fill the grey tank with liquid. As a convenience, most coaches today are outfitted with monitor panels that register the levels in each tank, making this task somewhat easier. Always fill the black tank at least three-quarters full and then evacuate it. Due to the solid nature of the waste, it will not drain properly and blockages will result if the valve is left open while connected to the park sewer. This truly then, becomes a distasteful experience. The outlets from the holding tanks are usually routed into a single termination assembly at or near the side of the RV. That termination assembly is comprised of one main outlet for connecting to the campground sewer and two inlets, one from each tank. Between each tank outlet and the inlet to the termination assembly are the dump valves. One of the most common design flaws found today is the use of grey holding tanks with a smaller than three-inch drain opening, probably because the code for RVs still mandates the grey tank outlet must have a minimum diameter of one and one-half inches. The black tank, however, must maintain a three-inch diameter from inlet to outlet. More on this a little later. Common Problems (and their solutions) Problems and disappointments are common in life and they are common with RV use as well. It's the seasoned RVer who finds ways to minimize or eliminate them. Odor and blockages are two of the more common maladies associated with the waste systems. Dwarfing those two problems, however, is a third woe that virtually every RVer has experienced at some point and it seems, with increasing regularity monitor panel inaccuracy. The monitor panel has indeed minimized our waste system concerns by revealing to us, at the touch of a button, the exact level of contents in the black and grey waste tanks, as well as the fresh water storage tank and the liquid propane container. But what is more frustrating than, having just evacuated and flushed the holding tanks, a monitor panel indication that says the toilet tank is still three-quarters full. You know darn well it's completely empty, you just dumped it! The problem? Contaminated probes on the interior of the holding tank caused by tissue, soaps, oils, grime and sludge. It is common for tissue to literally hang onto the probes since they extend into the tank interior through the sidewall. If wet or damp tissue or matter connects any of the individual level probes with any of what's called the "common" probes, the monitor panel will indicate a false reading. This is quite common when the probes, (simply threaded machine screws in some cases), are installed too close together or are exceedingly long. Conversely, probes that are manufactured into the tank may be very short and susceptible to inaccurate readings caused by sludge and grime coating the inner walls of a maintenance-starved holding tank. Thorough tank rinsings will minimize false monitor panel indications. The RV parts aftermarket, thankfully, is rife with products to aid in this endeavor. Camco, long an industry provider of sanitation products, offers a product called the "RV Swivel Stik." This device, attached to a water hose, is introduced into the holding tank through the toilet and directs a rotary spray to all corners of the holding tank. Another device, the "RV Quickie Flush," also from Camco, is permanently installed on the holding tank and cleans the tank interior via a multi-directional spray head. Again, a common hose attaches and delivers city water to the device. There are many variations of this design by other makers as well. Thetford, produces an additive, "Level Gauge Cleaner," for holding tanks that is poured directly into each tank through the toilet and one of the sink drains. The "RV Hydroflush", from Valterra, is a handy sewer hose adapter that accommodates a garden hose and forces city water pressure backward into the tank through the outlet while allowing the tank to drain at the same time. This back-flush method has proven effective in not only cleaning monitor probes, but also in resolving blockage problems that result when the black holding tank valve is left open when connected to the campsite sewer. It is recommended to backflush the black holding tank after each evacuation. The clear plastic housing of this adapter easily allows the RVer to know for sure when the tank is adequately flushed. The above listed products only scratch the surface of the available aftermarket items. Be sure to check out the Camping World location nearest you for a more complete selection of sanitation aids. When repeated rinsings and cleanings do not completely dislodge the offending matter creating the false monitor panel indications, the last resort is to replace the troublesome probes by installing individual rubber threaded inserts, called "well nuts" into the side of the holding tank. Well nuts are simply a flanged, neoprene bushing with a molded brass nut embedded into it. They are available through RV service facilities and/or selected hardware stores and are installed by carefully drilling a 3/8" hole next to the faulty probe and inserting the rubber flange into the hole. Thread sealant applied to the machine screw prevents tank contents from seeping out around the treads. Tightening the screw with the probe wire attached expands the rubber flange inside the tank to create a leak-proof seal. The machine screw itself then, becomes the new probe. It is best to use brass or stainless steel machine screws for the probe. Though doable by the average RV handyman, it is encouraged to seek professional help if you have any doubts. Odors emanating from a holding tank are indeed a smelly nuisance that can be avoided once their causes are understood and solutions implemented. In past years it was common practice to simply mask the odors in the holding tanks and to combat the consolidation of the solid waste by using strong chemicals. In some cases, it seemed these chemicals were more obnoxious than the odor from the waste. Many different chemicals were formulated to aid in this dual task of masking the odor and breaking down the tissue and solids. For many years, formaldehyde-based chemicals seemed to work the best. However, as technology progressed and the dangers of formaldehyde poisoning came to be understood, other options became a reality. Today, formaldehyde and other alcohol-based chemicals are no longer recommended for use in either holding tank. Many RV campgrounds and state parks, in fact, now prohibit the dumping of formaldehyde-laced holding tanks into their waste systems. Rather than masking odors from the holding tanks, experts recommend using a biological additive, one that employs live bacteria to literally absorb and eradicate the odor-causing molecules. Many suppliers have now produced such an enzyme-based additive. Avoid using any "chemical" in the holding tanks, especially those that contain formaldehyde. Chemicals such as detergents and ammonia products may damage the seals in the termination valves. Also avoid using home brews or other concoctions discussed around the campfire. Realize suppliers spend lots of money on R&D, so why risk the integrity of the RV waste system for the sake of a few dollars. Once you switch over to the live "bugs," using other types of deodorants, chemicals and/or detergents will kill the good bacteria and defeat the purpose. And be aware that tank odors are not exclusive to the black water holding tank. Oils, soaps and other residue commingling and fermenting in the grey tank can also produce their own olfactory objections. This is especially true when old habits have us leave the grey termination valve open while connected in the campsite. Grey tank matter will adhere to the walls of the tank and quickly dry out, leaving us to the mercy of nature's own method for biodegradation which is smelly at best, as anyone experienced in composting can attest. New Paradigms As mentioned earlier, many RV makers choose to install grey water holding tanks with only a 1-1/2" or 2" outlet. This practice can actually contribute to the proliferation of grey tank odors and false monitor panel readings. Many believe it would benefit every segment of the RV industry if manufacturers choose instead to use only 3" outlets on both grey and black holding tanks. RVers would benefit by realizing a quicker exit flow rate during dumping. Tests have proven that faster dumping sequences will increase the flushing action resulting in all waste, residue and sludge being quickly washed away rather than having them slowly recede down the tank walls and trickle through a 1-1/2" opening. One company has even taken this line of reasoning yet further. PhaseFour Industries, has developed a complete RV Waste Evacuation System by incorporating it's unique electric termination valve, the "Drain Master" on both holding tanks. In this new concept, both tanks are constructed with 3" outlets and each is equipped with a Drain Master located very near the outlet of each tank. Placing the valves at the tank outlets rather than at the termination assembly protect them from damage caused by bottoming out the RV. Keep in mind that all drains must have a continuous, gradual slope. The longer the run, the lower the termination assembly must hang. Positioning the valve at the tank outlet will also greatly reduce, if not eliminate, blockages in the 3" piping on some coaches with long drain runs. Both tank outlets can be quickly brought to a termination assembly and then a single 3" drain pipe routed to a side or rear connection point. With this system, it would be in the best interest of the user to leave both valves fully closed until the tanks reach capacity and then evacuate, dumping the toilet tank first, followed by the grey waste tank. The switches for the electric valves can be mounted conveniently close to the monitor panel, thereby eliminating the need to traipse outdoors often or in inclement weather to open the valves. By leaving the grey tank valve closed while connected to a campsite sewer, odors are virtually eliminated since the aforementioned additives can remain in the tank and be allowed to do its work. And, monitor probes will stay moist and free from grime ensuring the panel reads correctly. Drain Master electric valves are readily available in the aftermarket and anyone can easily retrofit existing termination assemblies and update their RV. The big push, however, should be aimed at the RV manufacturers to consider installing these valves and incorporating this new thinking at the OEM (original equipment manufacturer) level, thereby realizing a win-win situation. The RVer benefits as outlined above, plus the manufacturer can streamline his parts ordering task and redesign the termination assembly for easier factory installation while maintaining maximum valve protection. Those RVers with coaches bordering on electrical bankruptcy need not be overly concerned about the amp draw of the Drain Master. At 12-volts DC, each unit draws about a half an amp during each cycle. Additionally, the valve is equipped with a manual override that permits valve operation even if no battery voltage is available. Durability is a moot concern as well. Each unit is rated for a lifetime 6000 cycles. At a user rate of say, three evacuations per week, one would log over thirty-eight consecutive years of full-time RVing before worrying about wearing out the motor or internal gearing (another point for manufacturers to consider). The major toilet manufacturers have also put their creative juices to work and each has issued new and updated versions of their most popular models. Thetford has introduced the new Bravura toilet with a three year warranty. The Bravura is earmarked as the successor to their mainstay Aqua Magic series. For those RVers seeking a high end sculptured china toilet, the electrically operated Thetford Aria could be the one. Sealand's flagship toilet, the Magnum Opus is also a featured entry in the high end china toilet lineup. This model emulates residential styling with one-touch flushing and is available in designer colors. Sealand also has developed an interesting flushing system - the VacuFlush. This system utilizes what company literature calls a pump-generated vacuum to quickly clear the bowl of waste in a fragmenting manner which literally breaks up the solids. This obviously minimizes the chances of blockages anywhere in the black system to the point of non-concern. So what does all this mean? Just that those RVers interested in upgrading their on-board accouterments have a plethora of options to consider. The state of the technology for RV waste system products is at an all-time high right now and all RVers are encouraged to do a little homework and then take advantage of this opportunity. Coupled with a smattering of preventive maintenance practices this could result in many years of trouble-free operation of RV waste systems.
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