The Lectra/San Waste Treatment System

The Lectra/San Waste Treatment System

By David and Zora Aiken

No category of boat gear prompts as much discussion, distress and occasionally outright disgust than the marine head. Confusing and sometimes conflicting regulations make a difficult situation seemingly impossible to resolve.
So when it was time for us to install a new head system, we first spent some time conducting a study of other boaters' experiences and recommendations. We spoke with several boaters who switched to the Raritan Lectra/San MC, a system that treats sewerage and allows it to be discharged (at least in some areas) rather than held onboard in a tank.

Treating sewerage, rather than storing it, is an option that has become increasingly popular, and the boaters we spoke with were very satisfied with the operation of the Lectra/San. Given the subject, that's saying a lot, so we decided to join the converts.
Raritan's Lectra/San MC first macerates the sewage and then uses electrically charged saltwater to kill bacteria. After destroying bacteria and viruses, it reverts back to salt and water. When the treated discharge empties into the water, it does not add any illness-causing elements to the environment, so it meets EPA Type 1 standards for overboard discharge.
Despite the system's proven ability to disinfect waste, No Discharge Zones exist were boats are prohibited from emptying any sewage, even that treated to the EPA standard. But we nevertheless moved ahead with our project.
PLANNING THE PROJECT
The main installation considerations before purchasing a Lectra/San MC are available space, power consumption (it draws about 1.7 amp hours per 2-minute use), and, of course, the overall feasibility of the individual installation.
Raritan's Lectra/San Waste Treatment System
The space issue is probably the easiest to resolve. The treatment tank is truly compact, measuring 16 inches by 13-5/16 inches by 9-3/4 inches. It must be positioned so its top is at the same level as, or lower than, the toilet's discharge fitting. We'd hoped to fit the tank in a locker conveniently situated directly behind the toilet, where sliding doors would provide easy access should the need arise. But as the hull shape usually tapers locker spaces in heads, instead, we found a good spot in a cockpit seat locker.
This involved building a platform base to mount the unit securely. As the tank installs in line with the discharge hose, we routed new hose from the toilet through the under-sink cabinet, through an aft bulkhead and into the seat locker. It's still within the recommended distance of 3 to 6 feet from the toilet itself. Installation may require a vented loop, which prevents back siphoning and backflow, depending on the relative level of tank to toilet.
After determining the tank's location, we now measured for the hoses and made a list of required fittings and other materials. Our installation included marine plywood, some 1-inch square wood cleats, epoxy glue and stainless-steel screws for the mounting base; 1-1/2-inch ID odor-resistant sanitation hose (which has a smooth interior); and all-stainless hose clamps. Included with the Lectra/San is a Control Indicator Panel and saltwater feed tank (optional, but needed for our installation). Installation instructions specify the type of wire and other electrical fittings needed for 12-, 24- or 32-volt setup. Other miscellaneous supplies included PVC cement, for attaching hose fittings to the unit, and Teflon tape for all threaded connections.
Lectra/San MC, a mini onboard treatment system, uses salt to treat sewage immediately and automatically with each flush and meets the USCG requirements for a Type I MSD.
THE INSTALLATION
The mounting platform is made of 1/2-inch marine plywood, with wood cleats glued and screwed to the top, framing the unit to prevent any possible side-slipping. It sits on substantial supports screwed to cleat stock mounted to the hull in the locker, forming a solid base for the Lectra/San. Mounting straps hold it tightly to the base. A rubber pad under the tank helps to minimize noise and vibration.
Next we turned our attention to the installation of the new toilet, a manually operated Cricket from Raritan. This unit didn't fit the existing mounting base in our boat's head, but by adding a wooden support piece and angling the placement slightly, we were able to install it without any extra construction to the head sole. As with any such installation, if the toilet is below the waterline, add a vented loop to prevent siphoning.
After mounting the toilet and the treatment tank, the hoses were cut to length and connected. In small spaces, connecting hoses to fittings is difficult. To soften stiff hoses so they connect more easily to hose barbs, leave in the hot sun for a while or place in hot water for a few minutes. Our setup also includes a diverter, or "Y", valve and a small holding tank, to give us legal options in case of a power loss or when cruising offshore.
Wiring involved connecting the positive terminal on the treatment tank to a power distribution center (the unit requires a 60 amp fuse or breaker), and negative terminal to a negative distribution post. We used 6 AWG wire, the recommended size, allowing for the distance from the panel (or post) to the tank and back to the panel, and a 3-percent voltage drop. A cable from the Control Indicator Panel plugs into the back of the treatment tank. Luckily, this panel mounted very close to the toilet and followed the same wiring path as the discharge hose. A supplied template simplified cutting the hole for the panel.
Sample installation of Lectra/San MC with vented loop (above waterline).
LECTRA/SAN OPERATION
On a boat with an electric toilet, installation can also be setup for single-touch operation. The same button on the panel automatically activates the flushing mechanism and the treatment system. For manual toilets like ours, a sensor kit is available that activates the unit automatically after manually pumping three to five strokes, generally within a 10-second time period. This sensor is not essential to operation. The push-button mechanism works fine. Provided the boat is used in saltwater, no other components are needed. The salinity of ocean water is sufficient to operate the system.
If the boat is usually operated in fresh or brackish water (or if the Lectra/San is used with pressurized freshwater), Raritan recommends installing a salt-feed tank. The smallest, a two-gallon tank, requires adding pre-mixed salt and water (you mix it in a bucket). Each time the unit is used, some of the salt solution is mixed with the incoming water to provide the proper salinity. An optional four-gallon tank automatically adds the required salt to the system when hooked up to a pressurized freshwater supply. It's also possible to add salt to the system by simply pouring table salt into the toilet bowl with each usage. The control panel indicates if sufficient salt is added or if more is needed.
For those considering a Lectra/San, Raritan's website has a manual, parts lists and other helpful information.

A version of this story previously ran in Mad Mariner's DIY Boat Owner magazaine.