I am active in several different “forums” or on-line chat rooms focused on cruising etc. In them it is common for people to ask questions of the group, then different “experts” weigh in with free advice, often times this exchange is very valuable.

Occasionally a healthy “challenge” to an answer is posed by someone who disagrees.

In the past week or so, someone challenged my suggestion to occasionally hit one’s water tanks with some bleach… especially if you’ve been transiting some rural areas where well water is common.

I wrote that I occasionally “hit” my system with a half cup of bleach … especially if we have been transiting rural areas.

I was challenged on that dosage suggestion. So, I did some research.

Things that vary are the concentrations of the sodium hypochlorite in the household bleach one buys. Reportedly, 6-8% is typical. The size of one’s fresh water tank(s) also varies.

When I googled around to get the right dose, I learned that 1/2 teaspoon can treat 5 gallons of drinking water. The sources were authoritative government sources like the EPA and some state agencies, as well as some businesses in this field. Their answers varied a little but they were all in this same ballpark.

Shellerina has two 65 gallon fresh water tanks. So 13 teaspoons of household bleach should treat 130 gallons; 13 teaspoons is approximately 2 fluid ounces. So, I learned that a quarter cup instead of a half cup would be the right dose for OUR system.

Now, if I am regularly drawing water from these tanks, and re-filling them every week with “city water” I probably don’t need to add ANY bleach at all. The fresh water system is not stagnant, and it is being replenished with treated municipal drinking water.

We used to live in Maine, and we had a drilled well. After having it serviced, the vendor would “shock” the system with a LOT of bleach. They said, “When the smell of bleach goes away, it is OK to drink again.” Pretty un-scientific… but he was the professional, and went with that advice. If we smell chlorine at the tap in our boat, we don’t drink it, (or water the herb garden plants! LOL). Rather, we flush it out for a few days taking showers and doing dishes etc.

Related:

We “never” hook our boat up to the marina’s pressurized water system. There are two reasons for this. First, I want to keep drawing water from my own tanks to keep it fresh!

PLUS if we were to leave the boat for any length of time, and a leak in our system could cause an unlimited supply of city water to fill my boat; I am not comfortable that my only line of defense would be my bilge pump(s). Any number of things could contribute to that line of defense failing to keep up with the endless supply of pressurized water flowing in!

Lastly, we actually make a habit of having a 2.5 gallon jug of spring water aboard over our sink. We use it for making ice cubes, coffee, tea, and re-filling our water bottles. This habit dates back to the “old days” of winterizing our systems with pink non-toxic anti-freeze, etc. Even though we have not winterized in years because our seasonal migration patterns have changed. The old habit remains!

OK… one more tip. Do not fill your fresh water tanks from a fresh water hose near the pump out station! You have no idea when and if their hose has been inserted into a boat’s pump out port to “flush” their black water tank clean. If you gotta fill up there, simply hook up YOUR own hose to their spigot.