(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 8 of 8

Thread: Below Ground Irrigation Tank Pump Recommendations?

  1. #1
    DIY Junior Member
    Join Date
    Dec 2007
    Location
    Central Coast, CA
    Posts
    3

    Default Below Ground Irrigation Tank Pump Recommendations?

    I recently installed a 2500 Gallon below ground water tank to catch rain water from the gutter drains on that side of the house to feed 6 zone irrigation system described below.
    I will tie into my irrigation system with 1" PVC.
    I have 20amps / 115AC available near the tank.
    Irrigation system is comprised of 6 zones averaging (3) 5gpm sprinkler heads.
    I believe 30 PSI will be sufficient pressure to run 2-3 zones at a time.
    The bottom of the water tank is 9'-10' below highest sprinkler head.
    The system is currently fed from city meter water through an
    above ground anti-siphon valve.

    Using this info. can someone recommend a pump type and model to adequately power this system?
    How about an inline filter to prevent clogging of the sprinklers and some drip lines although the water should be fairly clean since it goes through a catch basin with 1/8" screen before entering the tank?
    Great Forum! Thanks in advance for any recommendations.

  2. #2
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    Location
    San Diego
    Posts
    9,001

    Default

    http://www.waynepumps.com/manuals/WLS_Series.pdf

    Your request to run 3 zones at a time adds up to 2400 gallons per hour. With the 9' head, you would be right on the edge with the 1 hp pump, which will run on a 115v @20 amp circuit. You would be better served with the 1 hp, but that would require a 25 or 30 amp circuit at 115. A better idea is to either arrange to have 240 for the motor, or rethink your zoning. With the array of timers available, there is really only a need to run one zone at a time. You can easily cover any size of property using timers and appropriate zoning.

  3. #3
    In the Trades Bob NH's Avatar
    Join Date
    Oct 2005
    Location
    New Hampshire
    Posts
    3,307

    Default

    You need to look at your requirements to see what you need.

    Your water supply is limited to a 2500 gallon cistern.

    How often does it rain to collect 2500 gallons of water? How many gallons per week can you rely on getting? Are you going to fill the cistern with city water when it doesn't rain?

    You want to run 2 or 3 zones at a time with an average of 3 sprinkler heads at 5 GPM each. Let's consider 2 zones at 15 GPM per zone. That would require a 30 GPM pump, which will empty the tank in 83 minutes.

    A more reasonable pump would do one zone at a time so it must supply the largest zone with 30 psi.

    A 1/2 HP Goulds 13GS05 submersible pump will deliver 16 GPM with a little margin for 30 psi, and it can be throttled to 4 GPM without distress where it will provide about 65 psi.

    A 3/4 HP Goulds 18GS07 submersible pump will deliver 25 GPM with the same margin and can be throttled to 6 GPM where it will provide 75 to 80 psi.

    Shallow well jet pumps would give you 16 GPM for a 3/4 HP Goulds J7S and and 21 GPM for a 1 HP Goulds J10S. The could operate as low as 3 GPM without a problem and probably lower.

    A 1 HP Goulds G10 Irrigator pump would give you 30 GPM at 30 psi with a little margin. It is described as a "self priming centrifugal" but such pumps can be a problem to prime.

    With any of the above you can operate them without a pressure tank if you use your valve control system to operate the pump. You must have a relief valve on the submersible pump, piped back to the tank or installed in the line where it comes out of the pump. You should have a relief valve on the other pumps if you operate without a pressure tank and switch; piped to return to the cistern.

    The cistern should settle out any sand large enough to plug the sprinkler heads and the screen on the pump inlet should catch anything like leaves or plastic that might get into it. I would not add a filter.

  4. #4
    DIY Junior Member
    Join Date
    Dec 2007
    Location
    Central Coast, CA
    Posts
    3

    Default

    [QUOTE=Bob NH;114615]You need to look at your requirements to see what you need.

    Your water supply is limited to a 2500 gallon cistern.

    How often does it rain to collect 2500 gallons of water? How many gallons per week can you rely on getting? Are you going to fill the cistern with city water when it doesn't rain?

    You want to run 2 or 3 zones at a time with an average of 3 sprinkler heads at 5 GPM each. Let's consider 2 zones at 15 GPM per zone. That would require a 30 GPM pump, which will empty the tank in 83 minutes.

    A more reasonable pump would do one zone at a time so it must supply the largest zone with 30 psi.QUOTE]

    I was mistaken about my sprinkler heads. I checked again and my sprinkler heads are Rainbird 10f's which only put out 1.58 GPM at 30 psi, with 3-4 heads per zone X 6. I just installed the tank this summer so I haven't experienced how much water the gutters will contribute to filling the tank. The irrigation system is presently run on city water and pressure. The tank is to supplement city when it has rained. I also have the option of filling the tank via a year-round stream that is 150 linear feet away and 25' below the inground tank. I would use a portable pump to fill the tank from the stream.

  5. #5
    Sprinkler Guy Wet_Boots's Avatar
    Join Date
    Mar 2007
    Location
    Metro NYC
    Posts
    798

    Default

    If you really want to employ a cistern for lawn watering, consider severing the city-water connection. Interconnecting city water and ground water, if indeed you can even do it in California, can only be effectively done by way of an RPZ backflow preventer ($$$) which may subtract enough water pressure to ruin performance. Figure on using that year-round stream, if you can get away with it. If you have the acreage, all the pumps and strainers and backflow preventer money will be worth it. For smaller lawns, cistern watering is probably going to cost more than city water.

  6. #6
    DIY Junior Member
    Join Date
    Dec 2007
    Location
    Central Coast, CA
    Posts
    3

    Default

    I am already using a Wilkins 720a Pressure Vaccuum Breaker to prevent backflow. Meter water runs around $80/ month additional during the dry months (June-Oct) to water the 1/4 acre garden, no lawn, mostly drought tolerant shrubs, and a few plants that need a fair amount of water, ie. roses, ferns, begonias, fushias. Water shortages are a problem here and I expect the cost to keep going up, hence the cistern. Thank you Wet Boots. I be able to wean off of the meter completely.

  7. #7
    Sprinkler Guy Wet_Boots's Avatar
    Join Date
    Mar 2007
    Location
    Metro NYC
    Posts
    798

    Default

    PVB = no good for your cistern project. RPZ only need apply (same toxic-backflow protection, plus the backpressure protection the PVB does not possess) ~ Another factor in the use of a cistern is making sure mosquitos can't breed in the water (West Nile Virus concerns)

  8. #8
    In the Trades Gary Swart's Avatar
    Join Date
    Sep 2004
    Location
    Yakima WA
    Posts
    7,246

    Default

    You'd better make sure you can draw water from that stream legally. That sort of thing is very tightly regulated at least where I'm located.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •