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.
Merrill Water Systems LLC