Storing well water to relieve stress on shared well

Discussion in 'Pumps and Tanks Well Forum & Blog' started by jaholmes, May 28, 2013.

  1. jaholmes

    jaholmes New Member

    Messages:
    2
    Location:
    Sammamish, WA
    This is probably a slightly odd question, but here goes:

    Background:
    My wife and I recently purchased a vacation home near the ocean in Anacortes, WA. The home is part of a well association and shares a well with eight other homes. The well is only about 200 feet from the ocean at high tide (why the current location was chosen is a bit unclear to me), and so there is reasonable concern about salt water intrusion. Chloride levels have hovered at around 50ppm for years, but they've asked residents to keep the water draw to 100 gallons per home per day as a precaution. Our average will certainly be below this, as we're only vacationing there now, however we were having thoughts of moving there at some point, and a 100 gal/day limit for a family of four is concerning.

    Question:
    To avoid stressing a well like this, are there any turnkey solutions available that would, say, do a timed draw on the well (into a 200+ gallon storage tank) during off hours (e.g., midnight to 4am)? The idea would be to fill the tank at a rate of no more than 100 gal/day, and to reduce stress on the well while also allowing our peak water usage to exceed 100 gal/day periodically. Hope that made sense!

    Any thoughts?

    Best,
    Aaron
    Last edited: May 28, 2013
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,081
    Location:
    NW Ontario, Canada
    The load on the well should be measured in GPM, not gallons per day. Most pumps need at least 1 GPM as a minimum draw to keep cool so 100 gallons at minimum draw would be 100 minutes.

    A 200 gallon pressure tank would not give you 200 gallons of water, only about 60 gallons, so unless you use an unpressurised tank and a second pump, you need a much larger tank. You would probably be better off burying a 1000 gallon tank and adding your own pump to it. the tank could be filled with a flow limiting dole valve.
  3. valveman

    valveman Moderator Staff Member

    Messages:
    4,522
    Location:
    Lubbock, Texas
    I agree with LL that intrusion would be less when pumping out 1 GPM for 100 minutes, compared to pumping 10 GPM for 10 minutes to get your 100 gpd. You just need a storage tank to store it in. The larger the storage tank, the more ahead you can get on the 100 gpd usage. After 10 days of using 50 gallons per day, the storage tank could have a 500 gallon surplus to use as needed. With a booster pump on the storage tank, you could get much more than 100 gpd on some days, as long as you have surplus.
  4. jaholmes

    jaholmes New Member

    Messages:
    2
    Location:
    Sammamish, WA
    Thanks guys, this is very helpful.

    Understood, and that's really the theme of my question. I don't think the 100 gal/day thing was meant as a load figure, rather simply an easy-to-remember rule of thumb to help limit the load on the well. The association doesn't have enough data yet to know what's sustainable and what isn't in terms of load, since the chloride measurements are only taken annually (by vote of the association members, this was recently changed to quarterly, but those numbers don't exist yet). Consequently, they can only correlate annual usage to chloride levels. It's clearly wrong, but it's all they have to go on at the moment.

    Thanks, yes, this sounds like what I was thinking of. I'll do some research along these lines. I'm not sure I want to find the room for a 1000-gallon tank, but I'll take a look at the common tank dimensions and start pondering where I might keep one.

    Thanks valveman. Regarding the saltwater intrusion, that's what my intuition was telling me, so it's good to have some confirmation. Again, the association simply doesn't have enough test data to suggest what a reasonable (in terms of GPM) load is on the well to keep the seawater out. I suspect that good data would put everybody's minds at ease, but it'll be a while before we have that, and I'd like to plan for bad news. Not to mention that having a surplus of good water on hand seems like a good thing by itself. :)

    I'm not sure exactly how involved a project like this is, though. If there are any similar documented projects that you all are aware of (or good books?), I'd be much obliged for any pointers!

    Thanks again!
    Aaron
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