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Explanation of Two Line Jet Pumps & Drinking Water Wells WaterAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• Explanation of Two Line Jet Pumps & Drinking Water Wells, Well Problems & Repair Advice
• Types of wells and water supply systems and what to watch out for with each
• Well pump & water tank diagnosis & repair procedures

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. © 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

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

Refer to this rough sketch of a served by a two-line jet pump located apart from the well. In our drawing the two line jet pump which draws water from the well and the water pressure tank are shown located separately from the well itself, and the well and its casing are shown located inside of a well pit. Well pits such as the one we've drawn are used especially in climates exposed to freezing weather, as a way to get access to the well casing and well piping and to route well piping out of the well through the top of the well casing and on to the building while protecting it from freezing. In addition to showing a well pit in this sketch, we discuss and illustrate well pits a bit more at Well Pits A more modern device, the pitless adapter which permits a water tight piping connection out through the side of the well casing is shown in our sketch at Components of a Drilled Well with a Submersible Water 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. 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. (In our sketch see the two arrows showing water entering the bottom of the piping.) If we have absolutely no water in the piping, and no water in the water pump, we've lost prime and the two line jet pump would be unable to bring water back from the well. If this happens it is possible to re-prime the pump with water from another source. Check valves installed at the proper location at the pump and perhaps elsewhere can help prevent loss of prime on this system. This 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 drawing.

• 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 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.
• 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 Actually In the Well and How Much Water Can Be Drawn Out.

Water Tank Maintenance & Repair Chapter Index

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 REPAIR GUIDE & COSTS
WATER PRESSURE LOSS DIAGNOSIS GUIDE
  WATER PUMP PRESSURE CONTROL ADJUSTMENT
  WATER PUMP PRESSURE CONTROL REPAIR
WATER PUMPS & TANKS & WELLS
WATER PUMP CONTROLS & SWITCHES
PUMP TYPES & LIFE EXPECTANCY
  PUMP, ONE LINE JET
  PUMP, TWO LINE JET
  PUMP, SUBMERSIBLE
WATER PUMP & TANK SAFETY
WATER SUPPLY & DRAIN PIPING
WATER TANK TYPES: WATER, OIL, EXPANSION, ALL
WATER TANK LIFE EXPECTANCY
WATER TANK REPAIRS
WATER TANK AIR, HOW TO ADD
WATER TANK REPLACEMENT
WATER TANK PRESSURE CALCULATIONS
WATER TANK SIZE & VOLUME
WATER TANKS HOW THEY WORK
WATER TESTING
WELLS CISTERNS & SPRINGS
WELL LIFE EXPECTANCY

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