I have an old farm property with a 3/4" galvanized water line that once supplied water from my house to some large chicken houses about 200' away that are now gone. A couple of owners ago there were 500 or so laying hens on the property. I'm looking to reuse this line to supply water to a small office/guest cabin that will be built on the only existing foundation of one of the former chicken houses. I located the end of the line, dug it up, flushed it and pressure tested it. I plan to use a dresser type coupling to connect the old galvanized pipe to 3/4" PVC which will be run into the building. My only hesitation is that its only about 30" deep. I am in Northwestern NJ (Hunterdon County) and code mandates that water lines be located a minimum of 42" deep, but that said, I feel as though during even the coldest of winters (especially nowadays) the ground MIGHT freeze 12" if that. Judging from what I know about the property I'd guess that the lines are 70-80 years old and were used from the late 1940s up until the late 1960s. Winters seemed to be much colder and longer back then and I seriously doubt that they would installed lines that could not be used in winter with 500 hens to provide water for daily. I'm aware that the lines are old, but as previously stated, they do hold pressure and installing new lines would be a challenge due to obstacles including a paved driveway, well water feed, underground electric feed and waste pipe for a septic. I'd rather just leave it alone and only replace it if there's an actual problem. I'd be curious to hear from others who either have old water lines on their property at less than frost depth or have installed them that way and how they made out. Obviously location plays a big role.

 

I don't know for sure but I think locally the call for 18" deep. Most of my water line is no where near that deep. In fact there are areas going up the hill where rock prevents it going deeper than a few inches although I do try to build up the ground in those areas. It's rare for any of my supply line to freeze.

The frost line is determined by the coldest temps it's ever expected to get which isn't the same as the normal low temp.

That said, I would be leery of old galvanized water pipe. They tend to corrode on the inside cutting down water flow.

 

Hi IH -

I am not a plumber or expert for sure, but I dug up my 1” galvanized steel service line from my well to the house about 10 years ago, because there was a leak which caused a large puddle up on the surface. The house was built in 1967, so I guess that made the line about 45 years old.

The pipe just about crumbled in my hand when I dug it up. I was shocked. Looking into that I found (if I have it correctly) that these galvanized steel lines just eventually rust out – and more so from the inside out (as mark stated in post # 2). The reason I mention this is because from what I gather steel lines like yours, 70-80 years old, would be a miracle if they were still working properly. Are you sure that that galvanized line isn’t much newer than 70-80 years?

The reason I think that is important is because if you build a cabin there might be an extremely high probability that you will have to very soon replace that entire line anyway. In other words, I would just assume if you build a cabin that either very soon you would have to replace the line or just do without water in the cabin.

I’m in S.E. Pa. and my frost depth I think is the same as yours. Off the top of my head I am wondering if you could find the coldest days in your area in the last 50 years and see how pipes at 30” would fare. I think you are correct 30” would be a code violation, but I can’t imagine that anyone would make you dig up the line a replace it for that. But maybe the pros would know.

 

I have had several instances where water lines buried at or below the code minimum froze. So, it is possible. Back when the farm was in operation the water line probably received frequent and heavy use which helped keep it from freezing. Now with the infrequent use of a office/cabin I'd say the chance is greater that it will freeze.

 

I suppose its possible that the lines were somewhat newer, but I bought the house from a gentleman who had owned it for the previous 40 years and he did not put them in. He gave me the history as well as old photographs showing the chicken houses, etc...dated in the 1950s. He bought the house from the chicken farmers. The pipe is certainly rough on the outside but it flows well and holds pressure. I hammered one end of the dresser onto it and it held up just fine. I think a lot of it must have to do with soil as well as water chemistry in terms of how well the pipe holds up or does not hold up. As far as frequent use vs. infrequent use that is something I had not thought of and will have to consider.

 

On a positive note:

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from this link:

https://www.biardandcrockett.com/blog/galvanized-pipes/

 

An unconnected steel/galvanized line will last much longer underground if it's not connected as the electrolysis will be minimal.