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This article describes various types of drinking water sources like wells, cisterns, dug wells, drilled wells, artesian wells and well and water pump equipment. We provide advice about what to do when things go wrong. Readers of this document should also see Water Tank Types and before assuming that a water problem is due to the well itself, see Water pump and pressure tank repair diagnosis & cost an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost.

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What are the Components of a Well with a Two Line Jet Pump?

How a Two-Line Jet Pump Works to Get Water Out of the Well

A two line jet pump refers to the observation that two pipes are connected between the jet pump and the well. In our photo at left you can see the two black plastic lines leaving the front of the water pump. A two line jet pump draws water out of the well by magic: it forces water away from the pump and into the bottom of the well through one of the pipes (usually the smaller diameter pipe). At the bottom of the well water from the jet pump is forced through a venturi device (a sort of funnel shaped opening) and then back upwards into the larger diameter pipe. Water flowing through the venturi device at the bottom of the well piping draws still additional water out of the well and into the larger diameter pipe that flows back to the building. The requirement to have some water to send down to the well in order to bring a larger quantity of water back is why a two line jet pump can't provide any water or water pressure in a building if it loses its prime. See WELL PUMP PRIMING PROCEDURE if you need to re-prime your jet pump. In our sketch above see the two arrows showing water entering the bottom of the piping.

The following list and definition of two-line deep well jet pump and water well parts and terms is organized from the top of the drawing towards its bottom and uses names that correspond to those shown in our ugly sketch above.

• A pair of well pipes leave the well casing through a water-tight cap on top of the casing and are connected to the appropriate fittings on the two line jet pump which is (probably) located in the building it serves.
  
  The well casing top in this example is located inside of a well pit but it could be simply buried in the soil. It is particularly important that the well cap on the casing be water tight since otherwise unsanitary surface water and debris can enter the well casing. Many well caps are not water tight, which is why modern drilled well casings extend above ground level.
  
  
• Compression Seal Well Cap is a special well cap with openings to permit passage of the two water lines (and maybe an air vent tube) out of the well to above ground.
  
  A compression seal well cap consists of steel top and bottom plates which "sandwich" rubber fittings which surround the water piping. As the two plates are bolted together they squeeze the rubber "sandwich" gaskets causing them to expand and seal both around the water piping and inside the diameter of the well casing.
  
  
• A "two-line" jet pump is shown outside of the well, either inside of the building or perhaps in a well pit or well house. "Two line" refers to the fact that two water pipes connect the pump to the well. Since the lift capacity of a two-line jet pump is not limited to the shallow-well depth of 27' chances are that where you find a two line jet pump installed it is drawing from a deep water well. Our sketch shows the pump connected to a water pressure tank which in turn supplies water to the building. The pressure tank is usually located very close to the jet pump but it could be elsewhere.
  
  
• Well Jet and Well Piping Foot Valve is a venturi device through which the two line jet pump sends water to collect and bring still more water back into the building. You can see Carson Dunlop's sketch of a foot valve here and also at the end of this list.
  
  
• Well Jet & Foot Valve Clearance from Well Bottom: (not shown) means that the well piping, bottom venturi, and foot valve are inserted into the well some distance from the very bottom of the well (inches to a few feet). We need this clearance to reduce the tendency of the well pump to pick up mud and debris from the bottom of the well.
  
  
• Static head (not shown in this sketch) is the height of the column of water inside of the well between the bottom of the foot valve and the top of the water when the well is at rest. We discuss "static head" and well recovery rates in detail at How Much Water is In the Well?

What is a Foot Valve used in a well and what goes wrong with foot valves?

If you keep losing prime at the water pump where a two-line jet pump is installed, it's probable that a check valve at the pump or more likely at the foot valve in the bottom of the well needs to be replaced.

Carson Dunlop's sketch at left shows how a foot valve works and where it is installed. Replacing a foot valve in the well requires that the well be opened and the well piping be pulled out to permit removal of the old valve and installation of a new one.

After replacing the foot valve you should shock the well since you've probably contaminated it by laying your well piping and parts on the ground (and foot valves at the plumbing supplier are not kept in sterile containers). We discuss how to shock a well at WELL SHOCK / CHLORINATION PROCEDURE our WELL SHOCKING GUIDE

Use links just below or at the left of each of the pages at our website to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

PLUMBING TOPICS
OIL TANKS
SEPTIC SYSTEMS
WATER PRESSURE REGULATOR ADJUST
WATER PRESSURE REPAIR GUIDE & COSTS
WATER PRESSURE LOSS DIAGNOSIS GUIDE
WATER PRESSURE & FLOW MEASUREMENT
  WATER PUMP PRESSURE CONTROL ADJUSTMENT
  WATER PUMP PRESSURE CONTROL REPAIR
  WATER PRESSURE REGULATOR ADJUST
WATER PUMPS & WELL TANKS
WATER PUMP CONTROLS & SWITCHES
PUMP TYPES & LIFE EXPECTANCY
  WATER PUMP, ONE LINE JET
  PUMP, TWO LINE JET
  PUMP, SUBMERSIBLE
  PUMPS, OTHER Kinetic Water Ram, Manual, Artesian
  PUMP, WATER PRESSURE BOOSTER
WATER PUMP & TANK SAFETY
WATER SUPPLY & DRAIN PIPING
WATER TANK TYPES: WATER, OIL, EXPANSION, ALL
  CAPTIVE AIR BLADDER WATER TANKS
  STEEL WATER TANKS
  BIG WATER STORAGE TANKS
  OPEN WATER TANKS
WATER TANK LIFE EXPECTANCY
WATER TANK REPAIRS
  CONTROLS & SWITCHES on WATER TANKS
  INTERMITTENT CYCLING WATER PUMPS
WATER TANK AIR, HOW TO ADD
WATER TANK BLADDERS & CAPTIVE AIR
WATER TANK BLADDER PRESSURE ADJUSTMENT
WATER TANK PRESSURE CALCULATIONS
WATER TANK SIZE & VOLUME
WATER TANKS HOW THEY WORK
WATER TESTING
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
  Basement Wells
  Cisterns
  Drilled Wells - steel casings
    Drilled Well with Submersible Pump
    Shallow Well with One Line Jet Pump
    Well with Two Line Jet Pump
  Driven Point Wells
  How Much Water is In the Well?
  How to Test Well Water Quantity
  How to Get More Water From a Well
  Hand Dug Wells
  Springs as Water Supply
  Well Pits

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• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
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