Connect 2 city water supplies together

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by daleclock, Jul 20, 2013.

  1. daleclock

    daleclock New Member

    Messages:
    1
    Location:
    Michigan
    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?
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,227
    Location:
    Cave Creek, Arizona
    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.
  3. Smooky

    Smooky Member

    Messages:
    567
    Location:
    NC
  4. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,296
    Location:
    Yakima WA
    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: Jul 20, 2013
  5. Smooky

    Smooky Member

    Messages:
    567
    Location:
    NC
    I missed the part about the duplex. So forget what I said before. Sorry about that.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,227
    Location:
    Cave Creek, Arizona
    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.
  7. Smooky

    Smooky Member

    Messages:
    567
    Location:
    NC
Similar Threads: Connect city
Forum Title Date
Plumbing Forum, Professional & DIY Advice, Tips & Connecting to City Sewer Main Jun 30, 2008
Plumbing Forum, Professional & DIY Advice, Tips & Push-Fit Connections and Deburring - a minor but important question Jul 2, 2014
Plumbing Forum, Professional & DIY Advice, Tips & Is it easier to replace a garbage disposer or just reconnect plumbing? Jun 27, 2014
Plumbing Forum, Professional & DIY Advice, Tips & How to connect PVC to 7.25 in OD clay pipe? Jun 22, 2014
Plumbing Forum, Professional & DIY Advice, Tips & Tape or Dope on Old Propane Stove Connection Jun 22, 2014

Share This Page