Galvanized steel lines in older parks

I’m about to enter a purchase contract with a park and the water lines are galvanized steel. The park was built in several phases over the decades, with the first phase in the late 1940s.

Doing some research, it looks like galvanized steel lines have a life expectancy of 40-60 years, depending on soil condition and water hardness. It seems like if you’re buying any older park with galvanized steel lines, regardless of the current condition, you pretty much have to factor in and discount for replacement of the water lines throughout the park. Even if older lines are functioning well now, it seems entirely possible they will start to fail in the near future. Thoughts?

I just thought I would bring this up since most parks are older with galvanized steel lines, and this is a really common occurrence that isn’t mentioned much.

I would say if you get 60 years on galvanized count your self very lucky. I recommend that a corrosion analysis (I like to used the Baylis curve) should be done when you are doing due diligence for a park that has galvanized pipe. Here are the factors that we look at that contribute to the life of galvanized pipe: Internal corrosion or mineral build up is dependent primarily on the following factors assuming we are talking about cold water.
Ph of water, Alkalinity of water / hardness of the water

Corrosion will also be increase in there is high levels of sulfur, dissolved oxygen,…
Iron bacteria can lead to corrosion and build up at the same time.

All Cities and many parks with or without their own wells are required to test for Lead and Copper this is really just a measure of the corrosive nature of the water being put through the system. We always check these results as they can give you some decent information.

Most public water system treat their water to minimize corrosion and generally try to maintain a ph of 7.20 or greater and may add additional chemicals to create a protective layer inside their mainlines. The Flint Michigan water crisis was created because of a change of water source (new source had lower ph and a higher chloride level both created a highly corrosive water that dissolved the pipes).

External corrosion factors (these factors usually create a electrical charge difference between the pipe and the soil leading to corrosion caused by electrolysis) : Soil type: generally the more clay the higher the rate of corrosion, volcanic soils tend to be more corrosive, high water table, electrical lines. Soils with high sand content are usually less corrosive. Pipe transitions from galvanized to copper or bronze suffer horribly from electrolysis (at water meters).

Galvanized pipes are a ticking bomb that will need to addressed and should be budgeted for accordingly.

Phillip Merrill
Merrill Water Systems LLC


Thanks Phillip, really good stuff.

Curious, you mention that a pipe transition from galvanized to copper or bronze will suffer from electrolysis. What about a transition from copper lines to galvanized steel?

Yes transitions from galvanized to copper will be a place of high electrolysis. The galvanized pipe will corrode first.


If you replace partial or full GI pipe systems have someone check the electrical service ground integrity. Service ground problems sometimes don’t show up until the copper or GI water pipe is replaced. This is because a service ground becomes deficient thru age or neglect but the water pipe picks up the stray currents so a problem doesn’t occur until the water pipe is worked on. A typical ‘hard’ ground would want to read well under 25 ohms to earth. A competent electrical contractor or good electrician can handle this.
Jim Allen

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I forgot to mention that a hard ground will help to minimize electrolysis, it won’t eliminate it, only minimize it.
Jim Allen