Disconnect water hose in winter?

Question:

A Yard and Garden article (November 9, 1998) stated that leaving hoses connected to spigots may cause interior water lines to freeze and burst. If the spigot valves are closed, I wouldn't think having a hose connected would make the spigots, the interior house water lines or the water inside them any colder or any more prone to freeze. A friend of mine insists that leaving hoses connected causes interior water pipes to freeze and burst even if the valve is closed. The 1998 article appears to support that view. I think the laws of physics do not support that view. Interior water lines can freeze and burst in the winter but people wanting to prevent that need to consider factors that influence the temperature of the interior pipes and pipe insulation. Also, considering how hose attachments and connections are prone to leak, I wouldn't think most water conservation conscious people would leave the spigot valve open, even in the summer.

Brian L.

Answer:

This is an interesting comment. Traditional wisdom states that garden hoses should be disconnected from the outdoor water valve in the winter to prevent freezing of water in the pipes inside the house resulting in bursting of those pipes. A brief search of the internet indicated that this traditional advice was often repeated. You comment that it doesn't seem possible that the water would freeze inside the house unless there was another problem (interior temperature or insulation) causing interior pipes to freeze behind the water valve.

I once wondered about this as well until a few years ago when I conducted an unintentional experiment. The garden hose was left attached to the water valve on the north side of my house well into the winter. When I finally noticed the problem, I saw that the house coupling was damaged from ice that expanded inside the hose (good enough reason to disconnect the hose). The next spring I noticed that the foundation of my house was constantly wet at the point where the valve came through from the crawl space under the house. When I went into the crawl space I found that the water pipe in the crawl space had split longitudinally behind the valve. In other winters (even colder winters), when the hose was not left attached, the pipe had not split. Repairing the pipe in the cramped quarters of the crawl space was not pleasant. Therefore, based on my experience I warn people to disconnect. I suspect that experiences such as this cause others to also issue the warning.

Your observation, however, is valid. Why did the pipe burst? Was it my failure to remove the hose? Was there another cause? I found no scientific study to verify the possibility of ice propagating past the valve and causing bursting of interior pipes. Perhaps someone will conduct such a study. This could be a good science fair project for a young scientist in middle or high school.

As I think of my experience, I wonder if the valve was not seating properly so that ice formed outside could propagate past the valve. The slowest leak would allow this. I wonder if the ice in contact with the valve on the outside would chill the valve enough that on another cold night ice would be allowed to form on the inside of the valve. These factors would once again suggest that it is wise to remove the hose. If there was even a slight leak, it should be fixed, but in the event that the leak could develop from exterior ice pressure during the winter, it would be good to disconnect the hose. Finally, removing the hose is a wise action to take when winterizing to prevent damage to the hose itself. In New Mexico, because of our typically dry winters, it will be necessary to reattach the hose periodically during winter to water when the weather permits. In the absence of proof that the ice cannot progress past the valve, removing the hose after use is advised. Thank you for your very thought provoking observation.

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Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

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