So while I wait on the Big Brown Truck to deliver a few more parts I need in order to finish installing the new Electro Scan treatment unit, I thought I’d build the salt injection tank system…
As Jeni mentioned in our last post, we are for the time being, located in fresh water. The new Electro Scan we just purchased requires salt water to function properly. Raritan sells a couple different sizes of salt feed tanks, and the designs have changed several times over the years. Ranging in price from about $100 for the bare-bones simple unit resembling a 2 gallon intravenous drip, to the slightly more complex $450 4-gallon-fresh-water-pressure-fed-automatic-12-volt-pump-injection-system. Check the interweb cruising forums, and you’re also likely to find “that guy” who merely “tosses a handful of table salt in with each flush”. I can’t imagine telling a guest (or my wife) to “throw some salt on that floater you just left before you pump it down”, or worse yet, having them (not my wife, of course ’cause she gets it) mess it all up and I’d have to go in there and do it myself. Salted turd? No thanks. Looking to strike a happy medium somewhere in between the absurdly complicated and the just plain absurd, here’s what I came up with.
Referencing several old Lectrasan (the older, and now deceased brother of the new Electro Scan) instruction manuals I found online, and a basic understanding of how a regular household toilet tank flushes and refills, I based the operating idea around a $9 toilet float valve from Homies. Since it fills from the bottom, I had to make a little leg assembly from PVC pipe fittings to hold it up off the bottom. This assembly is connected to our freshwater pressure water supply. It’s contained within a square 4 gallon bucket (because dimensionally it fit the best in the space we had available), using liquid tight tank fittings to get water into and out of the bucket (thru-hulls if you get them at West Marine), and a little bit of plastic tubing to get the water from here to there.
The most important piece of the puzzle, and one I decided I should buy rather than build was the t-check valve. Made by Raritan, and running nearly $40 is probably the most expensive part of this little DIY. It’s the connection where the saltwater from the bucket mixes with the flush intake line from outside the boat. There’s a little ball and a spring inside, and I just didn’t feel like building one from scratch. On the other end of the tube there’s a little flow control pinch valve that regulates how much saltwater brine is sucked into the toilet with each flush. Tee’d into the head intake on our Lavac toilet, each pull of the pump handle draws raw (outside) flush water into the bowl, as well as a metered amount of salt solution from the bucket (that I’m sure I’ll have to tinker with to get it just right.
Here’s a crappy little iPhone video complete with narration showing the basic way that it all works. We fill the bucket with salt, turn on the water, and voila, soupy salty brine water just waiting to get sucked into our toilet. As the salt is dissolved, we add more. The water is automatically replenished via the toilet valve. So now that this thing works, stay tuned for an update on the installation of the actual treatment unit….
DIY Raritan salt feed tank from Ramble On on Vimeo.