Saturday, November 27, 2021


Curing the curse of hard water RV plumbing issues

By Russ and Tiña De Maris

For folks who live up in the Pacific Northwest, the curse of “hard water” probably never enters your vocabulary. It never did for us – until we started spending time in the Desert Southwest. We quickly learned how much trouble a few “mineral deposits” in the water supply can create. Deposits in pipes, fittings chewed up, a whole host of plumbing nightmares.

There is a way that can help you counteract the negative aspects of hard water. Some swear by “the vinegar treatment.” Once a year, so say the resident experts, pump a solution of white vinegar and water into the RV water system, allow to stand overnight and dissolve hard water deposits. The dilution rate usually is set at 1:1 white vinegar to water.

Want to try it? First, turn off your “city water” supply and the power or gas to your water heater. Drain your hot water tank, and re-close the drain fitting. Next, if there’s water in your fresh water holding tank, drain it out. Now turn on the RV water pump. Open all your water-flowing fixtures and run them until air spurts out. Turn off the fixtures and water pump, and you’re ready for Phase 2.

You’ll need plenty of white vinegar. We recommend dumping about 4 gallons of the stuff into your fresh water tank, along with an equal amount of fresh water. If you can, drive your rig “around the block” to swish the solution around in the fresh water tank. Of course, you took the time to close the fresh tank drain valve before pouring in the vinegar!

Back home, turn on the water pump. Open your valves, one at a time, and let the water flow until you smell that good old strong vinegar odor. Close the valve, and repeat with all the fixtures in your rig. You’ll also be doing the “hot” side too, so your hot water tank will fill with this same solution. Again, allow the solution to “sit” for several hours – overnight or even longer if you can.

To make things work even better, use a water heater “flush wand” that pokes up into the water tank through the drain valve. Whoosh it out good to remove as much scale as you can, then close the drain. Do this trick before you turn on the water pump to fill up the system with the vinegar and water solution. Some have commented that vinegar may chew up the anode rod. Combining acetic acid with magnesium (the principal component of an anode rod) does produce magnesium acetate – and it makes for an interesting science experiment. However, rather strong acetic acid (35 percent) is required. By the time you dilute the already low-acid (5 to 8 percent) vinegar with water, our thinking is, sitting around in that weak solution for 24 hours or so isn’t going to chew up your anode rod. If you’re worried, pull out the anode rod and put in a plug. You may find that it’s high time to replace the anode rod anyway!

After your “stand time” clock has run its course, drain your fresh water holding tank and hot water tank. Refill the fresh tank with fresh water, and thoroughly run all fixtures until the odor and any color is gone. You may need to do this several times to get all the hard water minerals out of the system.

##RVT783 ##RVDT1295


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Dave J
1 year ago

Thinking that with the 10 gal hot water heater it might take more than just 4 gal of vinegar to get the 50-50 mixture.

Phil & Peggy
1 year ago

So much easier to just use an RO system. Your water will be so free of mineral deposits it will start cleaning previous deposits out of your fixtures by itself. Figured that out years ago in Tucson.

Brian Gilbert
1 year ago

My solution was to purchase a portable water softener. It was about $150 on ebay. It recharges with a pound of table salt and gives plenty of soft water; perfect for showering, doing dishes, or whatever. Why spend time and money fixing the damage of water scale if you can prevent it in the first place?

1 year ago

Very interesting information, but the first thing I think of is that most all motor homes use plastic pipe of some kind with all the new ones using PEX tubing. So thinking that after draining all the water from the tank & running the faucets until air comes out. Why not just use a 5 gallon bucket with 1 gallon of vinegar & fill the bucket, detach the inlet side of the pump & use a longer hose & stick it in the bucket & proceed to fill all the lines & faucets. Seems that would be easier & less cost doing it this way. Just trying to think out of the box. Actually most of the problems are corrosion from the hard water minerals that attack metal parts & not the plastic, so be sure to take out all the faucet screens & also clean them.

Colin Grant
4 years ago

Buy pickling vinegar instead of the regular and it is twice as strong but not twice the price.

Tom Fikes
4 years ago

After purchasing my new fifth wheel, I also bought a new water softener for my rig. I test the water at each site and put it into operation if my tester shows any sign of hardness. Chuck is right about the SW water. It is the hardest and most corrosive of all the water I’ve tested from coast to coast.

hank hoyt
4 years ago


Like Ken’s comment above, however why not just remove the screens first, allow them t sit in a container with the same solution then replace them as the last step in the process …


4 years ago

And then don’t forget to clean all the faucet screens of the extra minerals they will catch after cleaning. Never leave your readers with a new problem after they solve one.