Tuesday, July 29, 2014

Of Water Pumps, Tanks, and Shutoff Valves

Our water system is a bit more complicated than many.  There is a several hundred foot deep well with a Grundfos variable speed well pump in it.  It pumps water into a 1400 gallon water tank (although we seldom keep more than 1000 gallons in it) buried in the hill behind our house.  Gravity feeds the water down to the house, where a Grundfos pressurization pump in the garage raises it to 60 PSI.  (The amount of elevation required to make gravity do the pressurization pump's work we just do not have on our property.)

The pressurization pump was beginning to leak.  After a few calls, we found Idaho Pump, who came out to repair it.  The seals fail over time, and this pump has been in use since late 2005, so I guess that I am not too surprised.  The surprise was when the repairman went looking for water tank shutoff valve.  Clearly, you do not want to disconnect the water line and have 1000 gallons of water pouring out.  But he could not find such a valve under the house.

Our housebuilder was pretty sure that there was a shutoff valve at the tank--but there was no sign of in on the surface.  I used a metal detector to search the area, and while I could find plenty of copper (electrical), and something of iron, if there was a valve control, it was buried so deeply as to be unusable.

Anyway, Idaho Pump repaired the seal, and put in a shutoff valve just before the pressurization pump.  Of course, this mean emptying the water tank.  This was not terribly fast.  This raised the bill for the whole procedure to about $400, which doesn't seem terribly unreasonable considering how much he spent looking for the shutoff valve, waiting for the tank to empty, and installing the shutoff valve that should have been there in the first place.

The good news: even an end of the world as we know it event that knocked out our backup generator and therefore well pump means that we have a year's worth of water available through a gravity-fed spigot.

UPDATE: After the plumber left, we noticed the gravity-fed spigot wasn't working.  The plumber suggested that some dirt or a small pebble might be blocking the line.  Since the same line feeds the pressurization pump and the gravity-fed spigot (using a T-connection), and water was coming through the pressurization pump fine, this told me that the blockage was between the spigot and the T-connection.  The plumber suggested that since the pressure from gravity feed was not high, getting a female-female hose connector (like this one I bought at Home Depot), and running water from one of the pressurized hose bibs back through the spigot might knock it loose.  It took a couple of tries, but whatever was the obstacle cleared.


  1. In High School physics (With Vaughn, I had Burkard for Chemistry) I seem to recall that water can only be pumped 33 feet? That can't be right, there are deeper wells than that all over the world. What are the limits on depth of well?

    Can your well, as deep as it is, be hand pumped?

  2. 33 feet is the maximum column of water that can be held by a vacuum. You need a mechanical pump to do more.

  3. And this is a reminder to anyone who is having a similar system installed: make sure there is a cut-off valve, and know where it is.

    If I was really curious about this, I would get one of those pipe-snake cameras, and probe down the tank outlet pipe till I located the valve, assuming there is one.

    This assumes you have access to the inside of the tank.

    Which suggests something else: could one put a cover plate over the tank outlet instead of draining the tank? But then how would one get it off afterward, with the weight of the water holding it down?)

  4. Access to the tank is from the top. About five years ago, I went inside and cleaned it thoroughly of dirt and rocks that had come up from the well, and then used Clorox wipes to disinfect it, then threw in many gallons of Clorox to run through the system.

  5. A 33' column of water is 1 atmosphere. If your pump is more than 33 feet above a body of water you can't suck the water up. (Actually less. That is the theoretical max at sea level). If your pump is in the water reservoir and PUSHING the water then you can go much farther, depending on the type of pump, horsepower, pipe diameter and strength, etc.

  6. Gravity will feed the house from the tank; what's the backup plan for getting water out of the well and into the tank?

  7. Clayton,
    I think the average water usage in a household is 50+ gallons per day, so you don't have a "year's worth" on hand. In our travel trailer, we'll use only 12 gallons/day for 2 people if we're very frugal with dishwashing and showers. The RV toilet uses maybe a quart/flush. No laundry, of course.

    Your well must be very low output. I chatted with a fella in PA with a similar situation, his well only provides about 1/2 gallon per minute, so he has a similar setup as you. Our well will easily provide 10 GPM for as long as I want to pump it, and it's only 82 feet deep.

    I have a sand point well in my shop, and it will give 2+ GPM, with a simple shallow-well pump like yours.

  8. That sounds like a pretty neat setup Clayton.

  9. Nosmo: Backup generator feeds the well pump (along with some other essential circuits). I plan to install solar panels in the next month or so as a backup on the backup generator (which runs off LP gas). My expectation is that an end of the world scenario that lasts more than a few months is likely to be pretty darn serious.

    Our well is 10 gpm; the large tank was to have enough water for an extended period without power.

  10. In an end of the world emergency, we would not be using 50 gallons a day. A gallon a day to live on; another gallon or two for flushing. Perhaps a gallon for cooking.

  11. I feel your pain.

    My entire house does not have a shut off valve at the property entrance. This means, in essence, that the water company can't shut our water off. We discovered this when new meters were mandated by the town and they wanted to shut water off to install them. Surprise, nobody could find the buffalo box.