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Thread: Connect 2 city water supplies together

  1. #1
    DIY Junior Member daleclock's Avatar
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    Post Connect 2 city water supplies together

    I have an 100 year old house that was once a duplex. There are two 3/4 inch water supply line coming into the basement at opposite ends. One is used for the lawn sprinkler system and one is used for the house supply. Can I connect the two supply lines in order to increase the water flow and pressure to the whole system? If so do I need to have some type of back flow valve?

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    Moderator & Master Plumber hj's Avatar
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    Default water lines

    The one for the lawn irrigation may be on a different rate, since it would not have "sewer charges" on it. Whether connecting both together would raise volume and dynamic pressure is unknown because it would depend on how the piping was installed in the house/building. If you did connect them then you would need backflow prevention devices on BOTH lines.
    Licensed residential and commercial plumber

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    DIY Senior Member Smooky's Avatar
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    Sometimes there is a potable supply and a non potable supply. Some cities have reclaimed water that is used for irigation. They can not be connected together. You need to contact your city water department to find out what you can do.

    http://www.townofcary.org/Department...ter_System.htm

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    In the Trades Gary Swart's Avatar
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    Since this was once a duplex, it seems reasonable to think that possibly there are two separate water supplies to the house, but if that is true, there should be two meters. Is it possible the city has forgotten one of them? In any event, the irrigation line must have a back flow prevention device to protect the city water supply. I think you have some exploring to do to see if there is another meter buried somewhere. I see no advantage of joining the two lines. I would be concerned about these pipes being galvanized and becoming corroded. 3/4" is fairly small for both domestic water supply and irrigation, depending on size of the house and size of the irrigation system as well as the condition of the pipe. If you feel you need more water supply to the house, then you might be in line for a new supply line from one of the meters with a back flow where the irrigation splits from the domestic. I would consider a 1" line. Meter size would not have to be changed.
    Last edited by Gary Swart; 07-20-2013 at 05:36 PM.

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    DIY Senior Member Smooky's Avatar
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    I missed the part about the duplex. So forget what I said before. Sorry about that.

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    Moderator & Master Plumber hj's Avatar
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    quote; Some cities have reclaimed water that is used for irigation.

    BUT, I have never heard of it being used for "domestic" irrigation, usually just large areas such as parks and gold courses, and even then the piping is colored purple to identify it.
    Licensed residential and commercial plumber

  7. #7
    DIY Senior Member Smooky's Avatar
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    Here is a link to a news paper story about the potable water and the reclaimed water pipes getting mixed up. The water smells like aerated waste water so I do not understand how some people drank it for so long.

    http://www.city-data.com/forum/ralei...reclaimed.html

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