New hot water heater....rusty water?

Howie718

Hi Everyone,

Back in October I had a new water heater installed at a second property that I am taking care of while the homeowner, a family member, is away so the house is vacant.

It is a 40gal gas fired AO Smith. I go to the property every 2 weeks to check on things, and make sure everything is okay. A few weeks ago when I was there, I noticed that when asking for hot water at a sink, the water turns rusty brown when the hot water gets to the sink and clears up relatively quickly….say less than 30 seconds.

I was back there this past weekend and the same thing happened.

Does stagnant water in a water heater from lack of use cause this to happen?

Thank you, Howie

Jamie Hall

If it's only 30 seconds, it's much more likely to be a stretch of pipe somewhere between the water heater and the fixture. Happens to me pretty regularly (sob) and the culprit is a two foot long section of galvanized pipe I can't get at…

Gilmorrie

I suspect that the rust is coming from the piping, not the water heater.

Howie718

Thank you Guys!

Howie

Gilmorrie

Is there a faucet somewhere ahead of the water heater? If so, check it to see if the rusty water is there too.

Larry Weingarten

Hi @Howie718, Another test is to run some water from the heater's drain. If it's clear, great. If rusty, it could be the tank ,or old steel plumbing feeding the heater. Do you get rusty water from any cold taps? 🤔

Yours, Larry

Howie718

Hi all,

I will look to see if there is a faucet ahead of the hot water heater. Cold water always run clear.

Thanks, Howie

Howie718

Thank you all. I took water out of the drain valve on the hot water heater and it was clear. Not going to worry about this anymore.

Regards, Howie

jesmed1

This thread title caught my attention because we just replaced the 75-gallon gas fired water heater in our 100-year-old 4-unit condo building. I helped the plumber replace it, and when I opened the hot water faucet on my tub to get the air out of the pipes, the water ran rusty for several minutes. I told the plumber, and he said it was probably rust sediment from the water heater's pressure test at the factory.

Which made me wonder. Why would there be any rust in a brand-new tank from a pressure test? The tank is supposed to be glass lined, so there shouldn't be any exposed steel to rust. Not confidence-building when your water heater tank comes pre-rusted right from the factory…

Before the plumber installed the new heater, I removed the factory-installed consumable anode rod and installed a powered Corro-Protec anode rod, so even if the tank is already rusting from the inside, the powered anode should buy us some more lifetime vs the consumable anode rod that would be gone within a year because we use so much hot water among 4 condo units.

But I am wondering, is it common that new water heaters have rusty sediment that takes several minutes to dissipate from a tub spout?

Larry Weingarten

Hi, I've had rusty looking water come from from copper lines when they were refilled and run. Recirculation lines that usually operate at a slow flow can give a lot of "rusty" water when flushed under pressure. I don't buy the plumber's assertion that rusty water is sitting in the tank. Contact area with steel would be tiny because of the glass lining. I'll add that I've installed lots of heaters, and rusty water on first flow just isn't a thing.

Yours, Larry

ps. There is only a small correlation between water usage and sacrificial anode consumption. Higher heat absolutely speeds anode consumption. My approach has been to add a second anode to keep the tank going so service is needed less often.

jesmed1

@Larry Weingarten Thanks, that makes me feel better.

We had our in-street water mains re-lined a year or two ago, and that process stirred up a lot of sediment that I thought had been flushed out, but some was probably still sitting in the bottom of our water lines. When the plumber filled the new water heater, he used a "fast fill" method I hadn't seen before. After pressing the cold water supply onto the heater, and before the hot was plumbed in, he turned the cold water supply full on, then played "beat the clock" to plumb the hot side of the tank, hopefully before the water reached the top of the tank (he did beat the clock).

I now suspect his "fast" fill" method through a 3/4 cold supply with no back pressure created a higher-than-usual flow rate through our cold supply pipes, stirring up residual sediment from that water main relining project. That would explain why some sediment also appeared at our outdoor hose bibs.

mattmia2

when you fill the tank you get a lot more flow than normally flows in the pipe and it flushes out stuff that doesn't normally get disturbed. You will frequently see the same thing if you take the aerator off a faucet and run it at full flow without the restrictor in the aerator.

mattmia2

https://forum.heatinghelp.com/discussion/comment/1853560#Comment_1853560

same thing will happen if you open the relief valve to fill it or even open most laundry faucets all the way.

jesmed1

That water main relining sure stirred up a boatload of crap. Now most of it is probably in the bottom of our new water heater. 😅

mattmia2

My bet is that in the op's case they used a galvanized nipple or fitting or dielectric union in the connection to the water heater. that will make a little slug of rusty water if it sits for a few days or more.

mattmia2

also note that air is compressible so the air can leave the tank a lot faster than water through the smaller piping to fixtures and the fixture itself.