I made my own water filtration system that I use when filling my holding tanks. I take the approach that, no matter where it is from, the water is dangerous due to flukes, cysts, parasites, bacteria, and so forth. Many of the health problems in third-world countries are due to contaminated water. My “system” is pretty simple but my goal is one of those ‘ounce of prevention’ deals. With very little expense, I can filter the majority of the nastiness out of the water and, hopefully, avoid all of the problems that come from drinking dirty water.
To start, I bought two standard 10″ filter housings with 3/4″ inlet/output threaded ports. These housings will hold any standard 10″ x 2″ sized filter. I picked up several nylon fittings, some 3/4″ clear tubing, and a standard garden hose fitting. I then connected it all together so the dock hose is connected and water flows into the first housing, thru the 2 micron sediment filter, out the first housing, thru a short length of tubing, into the second housing, thru the .02 micron carbon filter, out the second housing, and thru a length of tubing that is directed into my take fill port.
I currently have a KX MATRIKX VOC 2 micron filter in the first housing. From the KX marketing material, this filter “is made from coconut shell carbon, which creates what many believe to be a sweeter tasting water. Because of the unique pore structure of this carbon, it is well-suited for chemical adsorption, including VOCs, and chlorine taste and odor. KX MATRIKX VOC filters provide 2 micron particulate filtration and extended life as a fine sediment filter.”
The second housing contains an activated carbon KX CERAMIKX 0.2 micron particulate filter. The real benefit is its ability filter the germs. Specifically, cyst reduction (NSF/ANSI Standard 53), chlorine taste/odor reduction (NSF/ANSI Standard 42), and 99.9996% E-Coli reduction.
To get the best results (from any carbon filter) the water should flow through the filters as slowly as possible. When connected to the dock water supply and not in a hurry, I turn the water on very slowly to increase the dwell time in the carbon filter. I’ve yet to fill from a can or rain catchment but my thinking is that the water flow will be pretty slow (gravity only) and this should be ideal. We’ll see if reality aligns with my thinking.
A carbon filter in a boat’s water distribution system is not the best of things because the carbon removes the chlorine from the system (even when there is no water flowing) and the carbon is a nutrient source for many microorganisms. The chlorine is a good thing as it kills bacteria and helps to keep the water sweet. The better approach is to use the carbon filter in the filling system which then delivers clean water into a into a clean tank. I should note that I still use a bit of chlorine (bleach) in my tank to prevent nastiness.
I have very little actual experience with this system so time will tell if it is helpful. I am under no illusions that it will remove every possible germ and nasty. However; it seems like a reasonable precaution to take.