Two line jet pump diagram (C) Carson Dunlop Associates Two Line Jet Pump Install / Repair

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This article describes the sequence of operating steps in a two-line jet pump water system.The process of diagnosis and the costs of the repair are explained.

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How a Two-Line Jet Pump Well Water System Works - Sequence of Operating Steps

Copper tubing on pressure control switch (C) Daniel Friedman

What happens when you turn on the water at a faucet in a building whose water is supplied by a two-line jet pump? (See the sketch at the top of This article for the basic components of a two-line jet pump system.)

The following steps describe normal operating of a building well pump and water supply system.

Other cases in which the well pump controls are not working properly, there is a problem with the controls, pressure tank, pump, or well itself are discussed

  1. Turn on building water at a plumbing fixture: open a sink valve, tub valve, or flush a toilet.
  2. Water runs out of the supply faucet, into the fixture, down the drain
  3. Water pressure and flow are being supplied to the building from a water pressure tank. If we didn't use a pressure tank, because water is not very compressible, the second water was turned on, water pressure in the system would drop below the pump cut-on pressure, the pump would turn on, and probably bring water pressure up to the cut-off pressure quickly, causing short cycling and burning up pump controls or a pump motor.
  4. Pressure in the water pressure tank and in the building piping system drops down to the well pump cut-in pressure. Typically this is 20 or 30 psi on a residential water system.
  5. The well pump pressure control switch senses the pressure drop, closes an internal electrical relay switch to turn on the well pump.
  6. The well pump motor runs, drawing water back into the building from the well by "sucking" water up from a shallow depth (a one-line jet pump can't draw water from much below 25 feet)
  7. Water is forced into the building water pressure tank and simultaneously into the building piping and on to the plumbing fixtures.
  8. If the pump sends water into the building faster than water is flowing out of the open faucet or plumbing fixture, the pump will "get ahead" of the water flow, successfully pressurizing the water tank, causing the pressure switch to turn off the pump (see step 10 below).

  9. If the pump cannot send water into the building faster than water is flowing out of the open faucet or plumbing fixture, the well pump will run continuously and water will flow out of the open faucet or plumbing fixture at a rate limited basically by the pump's water delivery flow rate in gallons per minute. You'll also find this condition if a building water supply pipe bursts. We say "basically" because the well piping and building piping and faucets themselves offer some back-pressure against the pump's flow rate. In this case, the well pump will continue to run until the building faucets or plumbing fixtures are turned off. At that point ...
  10. The well pump pressure control switch senses that water pressure has increased to the cut-out point, opening its switch and turning off electrical power to the well pump. The well pump has re-pressurized the building water tank and piping up to the cut-out or cut-off water pressure.
  11. The foot valve closes (at the bottom of the well piping) and/or a check valve located in the building on or close to the well pump closes, preventing water and pressure from flowing backwards down into the well, losing building water pressure and possibly losing pump prime.
    and if necessary

How to Diagnose Poor 2-line Jet Pump Operation or 2-Line Jet Pump Water Pressure

For our complete water pressure and pump, well, and piping problems diagnostic article list,


Separately we also provide
a WATER PRESSURE PROBLEM DIAGNOSIS TABLE. The following articles pertain if you have a private well, pump, and tank system for your building or if your incoming community water supply pressure and flow are just too low to start with:

  1. Water Tank Problems? 
    See WATER PRESSURE TANK REPAIRS. Examples of water tank problems include poor water pressure or the well pump rapidly turning on and off (short cycling).
  2. Water pump problems? Examples of water pump problems include poor water pressure or no water pressure at all. See
  3. Water piping or well piping problems? If your water pump keeps losing prime, a shallow well jet pump well line could have a bad foot valve (in the well
    ) or there may be
    a bad check valve on well piping at or near the water tank or near the above-ground water pump
    (CHECK VALVES, WATER SUPPLY) and so be losing prime.

    A leak in the well line piping itself can also lead to loss of prime.
  4. Well Problems? Do you run out of water or after running water for some interval water pressure and flow are poor? Well problem diagnosis starts

    Before assuming that there is no water in the well, check to see if the water pump is working properly, including
    loss of pump prime
    and a bad or leaky well piping foot valve
  5. Bad water pump or water tank pressure regulator control? 
    See WATER PRESSURE REDUCER / REGULATOR (not usually installed on private well and pump systems, often present on municipal water supply systems that use an in-building local water pump and pressure tank to boost pressure). Water pump pressure regulator switch diagnosis and repair steps include these:
    • How to Adjust Water Pump Pressure: The detailed, step by step procedure for inspecting and adjusting the water pressure control switch is discussed in detail
    • Diagnosing Water Pump Short Cycling on and off: If your water pump is clicking on and off too often or quite rapidly
      see SHORT CYCLING.
    • Diagnosing Water Pressure Drops without explanation when the pump stops,
      see WATER PRESSURE FALLS SLOWLY, ERRATIC PUMP: bad pressure control switch, building water running or leak, bad pressure gauge, bad check valve, bad foot valve.
    • Diagnosing & Repairing Lost Air in the Water Tank: The problem of lost air in the water pressure tank along with how to correct that condition are discussed beginning
    • Diagnosing & Repairing a Water Pressure Control or Water Pump Control Switch: We discuss diagnosing and repairing a water pressure control switch that sticks "on" or "off" or simply won't operate,
      at water pump Pressure Switch Repairs.
  6. Bad Hot Water Pressure? 
    See HOT WATER IMPROVEMENT especially if the building cold water pressure is acceptable but hot water pressure and flow are poor. Accumulated debris in a water heater, and debris from a corroded or disintegrating hot water tank dip tube or hot water tank sacrificial anode can also block the hot water outlet opening, resulting in low hot water pressure in a building.
  7. Bad cold or hot water pressure and flow just at certain plumbing fixtures? See our discussion
    of Poor water pressure just at certain plumbing fixtures just above.
  8. Problems with water treatment equipment can cause loss of water pressure or no water flow: a clogged water filter, or a malfunction in water disinfection or other water treatment equipment can cause a reduction in water pressure or even a complete stop in water flow in a building. S
    ee WATER FILTERS, HOME USE for details about clogged filters,
    see WATER TREATMENT EQUIPMENT CHOICES for our complete list of types of water treatment equipment.

Methods Cleaning the Water Pump Intake Screen or Well Bore Sediment

Reader Question: how to clean the well bore sediment or screen clog without pulling well piping

(Aug 18, 2014) Bill K said:
Would it be conceivable to use a jet pump to clean out sediment at the bottom of a water well bore? We have six windmills on our ranch that are all around 140 feet deep that are 50 to 60 years old and sediment can get to be a problem over time. I was hoping to achieve a new "lease on life" for these wells if I could clean them out in some way and a jet pump is the only thing I could think of that would be able to lift mud and such off the bottom if it could fit down the bore hole.



It's no surprise that articles on removing sand or silt from water wells mostly focus on filtering the water using various methods ranging from a cartridge filter to a centrifugal sand separator. But for removing sand or silt from the bottom of a well bore, well drillers have had to deal with this matter for generations and have several approaches.

The most common approach, provided we're not also going to exhaust the well's flow rate, is to pump silty sandy water from the well bottom for an extended period of time - possibly days. (Normally the water pick up in a well is set several feet above well bottom to avoid picking up settled debris).

You could use a 2-line jet pump whose pickup is at the end of the pair of pipes near well bottom COMBINED with some other jet to stir up muck to try to pump it out of a well bore, but you may destroy the pump in the process. Well drillers have a variety of approaches to removing debris from wells. Typically a pump particluarly designed to handle sludge is used. Some examples are the Waterra pump line (waterra dot com)

Or search for sludge-pumps made by a variety of manufacturers.

Assuming your well bores are lined, it's possible that your lining has leaked or corroded or cracked. So you want to inspect the well bore (well bore camera) and if necessary, insert appropriate repair sleeves to cut the dirt or sediment or sand entry rate into the bore.

In 2010 the state of New Hampshire in the U.S. published a helpful article "Sand and Sediment in Water Wells", WD-DWGB-3-14 online as a PDF.

Farmshow dot com has an interesting article about a home-made well-cleaner (Richard Guthrie's design) that uses a combination of a steel cylinder lowered into the well and compressed air - which may not be practical for deep wells such as you describe.

(Aug 19, 2014) Anonymous said:
Thanks Dan.

That gives me a lot more directions to go than I had before. I've been searching for an affordable well camera or even a rental place for one for several days now but they seem to be few and far between in West Texas. With six wells, not all working but we have plans for renewal on two, I'm tempted to buy one but at $3 to $4 grand or more each I'd hate to have one just sit for years after using it several times. I'd assume their resell value, if intact, would hold, though.

One personal theory of mine is that old well bores like this may also decline in production due to lime deposits at the layers of water production and may need to either be scraped in some way or acidized to promote continued flow. This would produce a lot of debris that would need to be removed from the bottom of the bore but the cost of drilling another well (hit-or-miss proposition at $$$/ft regardless) and either moving the windmill or putting in a solar pump like we've done on one last year makes you go "hmmmm....". The well that's given us the most problems over the years is a high sulfur content water well. As of earlier this year the sulfur aquifer or layer has either played out or caked over and what little water is coming out is now sweet but production has gone down to almost nothing. Hence my longing for a well camera to reduce the guess work. Have any suggestions for any brands or opinions yea or nay on personal ownership?


A bit costly to buy a well bore inspection camera. Here are a couple of ideas;

See if there are any chimney sweeps (probably not) in your area. Those guys may have a camera that can inspect the dry portion of the bore (which would be a partial exam)


See if you can partner with a local well driller - one of the younger, more interested, technical fellows but who does not have an inspection camera. Offer to share the camera cost with him or her in exchange for examining your wells. S/he will then have a tool and expertise that expands her business.

(Aug 19, 2014) Bill K said:
Thanks again Dan,

I finally had time to more carefully read over your suggestions and the well cleaner of Mr. Guthrie's in Early, TX is intriguing. My uncle may actually be acquainted with him as he's from that area. I may contact him or his family to get a better understanding of that cleaner's design. We have an old well cleaner in the barn that might be convertible to this method. And, yes, we have our own "magic pile" of junk that we've been re-purposing for three generations now! You NEVER throw anything away on a ranch or farm. Junk is a ag man's gold.

Our wells were drilled at a time that casing was only partially inserted down the bore to a depth, I'm assuming, that the rock layers began. I guess they thought the rock wall would hold for at least a generation or two but that would put us just about at the end of that time line.


(Aug 20, 2014) (mod) said:
Indeed the casing is usually stopped some short distance into the rock if rock is encountered - since we expect water to enter the well bore through fissures in that very stone.


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