Dear Dave,
Why is black water coming out of my RV faucets when first turned on, then runs clear? I also itch bad after showering in my RV, but not at the shower house. Can you please help. —Shirley, 2006 5th wheel Carriage
Dear Shirley,
Great. Now I can’t get The Doobie Brothers song out of my head… “Old black water, keep on rollin’. Mississippi moon, won’t you keep on shinin’ on me?”🤣
I would assume you are referring to actual black-colored water rather than what RVers typically call the black water, which is sewage from the toilet? I do not know of any way water from the black tank could get into a closed fresh water system. My guess is your fresh water system has gotten some bad, moldy water that has been sitting in the pipes, fresh water tank, or more likely the water heater.
Typically hard water at a campground
When you fill your freshwater tank or even connect to a water source at a campground, it is typically hard water from a well source. Recently I posted an article about filtering water and had some comments that said their campground had water from the local municipal water supplier and it had been treated. However, most campgrounds that I have been at do not have “conditioned” water with a traditional water softener, so it will have all the components of hard water.
Hard water contains calcium, rust, lime, and other minerals, including magnesium. When magnesium mixes with oxygen it can turn black. Even though your water system is somewhat closed, air is present in the freshwater tank through the gravity fill and the overflow tube.
Another possibility is mold or even algae, especially in the water heater tank. Even if you drain the water heater, if you do not flush it out with a flush wand or other type of pressure hose, about 2” of water will sit in the bottom as the drain hole is not at the very bottom. This water sitting in the bottom can turn black and typically “skunky” with a rotten egg smell.
I would recommend draining the entire freshwater system by opening the low point drain valves, and drain the freshwater tank and the water heater. Flush the water heater tank out with a flush wand that you can get on Amazon here.
I like this brand as it has a threaded metal wand rather than the plastic version that is just pushed on. I have had a couple owners write in that the wand part blew off into the water heater tank and it took a lot of work to get it out, if at all.
Clean the freshwater system
Next, clean the freshwater system thoroughly with either a half cup of bleach in 50 gallons of water, or use the Thetford Fresh Water Tank Sanitizer.
Fill your water tank at least ¾ full and drive around for a few minutes to splash it around. Then turn on the water pump and run the solution through all the faucets, shower, and toilet for a minute each to get the old water out and the new sanitizer solution into the pipes and faucets. Let it sit overnight, then drain and flush.
This should get rid of the black water and the itchy shower.
You might also enjoy this from Dave
Your RV’s fresh water system: What you should know
This is Part 5 of Dave Solberg’s “Everything you need to know about RVing” series. In this informative post, Dave looks at RV fresh water systems and tells you just about everything you need to know about them, whether this is your first or 101st trip.
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
Read more from Dave here.
##RVDT2440
Forgetting to flush a new inline water filter before hooking up to the RV will cause that, the charcoal from the manufacturing process for the filter needs flushed out BEFORE hooking up to the RV,
Forgot about that and that may have contributed to the issue. Good catch!
Joseph, you beat me to the draw! That’s what I was going to suggest.
Good catch Joseph! Sometimes I just assume and we all know what that means.
Been there- forgot that- and it resulted in the check valve of the water pump failing to hold and the pump then running every few minutes! Crawling under the bed, no fun, removed pump and cleaned the black charcoal particles from. Solved.
Would the charcoal cause the itching? I doubt it would, but who knows?
The first time I used a water filter, I had black stuff coming out of my freshwater faucets. As a newbie, I didn’t know I needed to rinse a new filter.
Thank you, Dave! 🙂 Thank you, especially for the information about sanitizing the fresh water tank! Why would you want to purge “Black Water” from your mind? It is one of my all-time favorites. 🙂
https://youtu.be/m4oZCtfmh44?feature=shared
Thanks again, have a great day, safe travels, and safe stays! 🙂
Have they checked their zinc anode on the hot water tank.
I don’t believe it is magnesium but the oxide of manganese in the water that is black (manganese dioxide)
Magnesium, manganese, and iron are common minerals that build up in your water system over time. When these minerals oxidize—i.e. mix with oxygen as they come out of your faucet—they can turn black, which in turn causes the water that flows out of your faucet to appear black as well.
it is actually the magnesium. Most likely coming from the campground water system. And safe to drink for a short time- if you dare.
Why would one want to put a product (Thetford Sanitizer) into your fresh water system that is labeled as requiring caution and hazardous waste procedures for disposal? Bleach would seem to be a much safer and less hazardous agent to use, with successful long term use, though bleach is not without its faults as well.
Not really any different. The bleach isn’t labeled like that because the regulators don’t know you might use it that way. It probably does warn you not to drink it.
so why aren’t water heaters designed so that they can be drained completely?
Re: Black in water at faucets can also be an inline hose filter w/ internal charcoal that clogged and is now coming apart. Always carry a spare filter and change filter if any concerns. Poor water quality can clog them rapidly. Great article/ response, as you seem to have covered all other possibilities.