Waste Master press release - December 2008 - RV waste disposal, gravity verses macerator pump - lots of controversy has emerged recently regarding dumping holding tanks using a macerator pump with a ¾” or 1” hose as opposed to dumping using the traditional 3” gravity hose.

The two different methods have differing advantages. The macerator uses a small hose which is easier to handle and store while the gravity feed is simple and most effective when the proper hose and fittings are used. The pump can pump great distances and uphill while gravity must flow in a downward angle. Gravity needs no power while the pump consumes 15 to 25 amps of 12vdc power during use. The pump is slower while gravity is faster.

Research has shown that the biggest majority (over 95%) of RV enthusiasts use RV parks and resorts to enjoy the RV lifestyle. Most RV parks and resorts have approved sewer inlets at each RV site and the inlet is located relatively close to the electrical and fresh water connections. Some of the older parks have sites without sewer hookups, however, provide a dump station for removing waste before leaving the park. Other folks never stay in RV parks and prefer to boondock in rest areas, truck stops or on private property. A small number of RVers use a home “clean out” drain to dump their tanks, and in some cases using a macerator pump is necessary because of the distance from the RV to the house, or because the house is much higher than the RV.

In order to understand the “best method”, we researched the industrial sector of commercial vehicles carrying and transferring liquids from vehicle to its ground source. The reason for this approach is that commercial vehicles fall under many regulations enforced by government agencies like the Environmental Protection Agency (EPA), the Department of Transportation (DOT) as well as state and county regulations.

In all cases (with the exception of septic trucks) gravity was the “best method” because the vehicle tank is located above the ground inlet. Very simple and very effective. The septic truck uses a special diaphragm pump system because it has to draw liquids out of the ground, which makes sense.
In addition, we found that all commercial vehicles that carry liquids, carry the transfer hose necessary to transfer the liquid from the truck tank to the approved ground inlet. All of this equipment is listed and tested to a standard of one type or another. Interestingly, the operators of these vehicles were all highly trained in the process in order to be licensed to drive these types of units.

We then asked countless RVers why they were unhappy with the current 3” hose and fitting packages they bought, and the answer was the quality is not sufficient enough to ensure a trouble free transfer by the second or third use.

From the RV industry perspective we started at the top looking at RVs where the cost is not a factor and found that none of them used macerator pumps! They do however, have the best possible hose available and use electric dump valves for convenience. Why, when cost is not a factor would these companies not use a pump to transfer waste from their coaches? The answer is that they all practice the “keep it simple” method of design and engineering.