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STEVE MAXWELL (SUBMERSIBLE PUMPS, JET PUMP)HOME & DESIGN: WATER WELLS
Submersible pumps aren’t as cheap
as jet pumps for a given size, but
they’re more than worth the extra
money for several unique reasons.
They move more water than other
pumps of a given horsepower and
they never need priming. That’s
because the pump itself sits below
water level in the well—wires and all.
You know you’ve got a submersible
pump because there’s no pump to
be seen anywhere. Water simply
flows into your home from a pipe
noiselessly. All submersible pumps
need to be supplied with electricity,
so wires or a conduit leaving your
home is another telltale sign you’ve
got a submersible.
Jet pumps are a popular choice
because they’re inexpensive and
can work in both shallow- or deep-
well situations. You can tell you’ve
got a jet pump because it sits
above ground and makes a kind of
whooshing sound as it operates.
Jet pumps need to be primed
before they’ll work, and even a small
amount of air in the lines stops them
from pumping. Jet pumps may be
common and cheap, though more
troublesome than submersibles.Water well pumps
There are three main types of water well pumps in the world: submersible pumps, jet pumps and
piston pumps. Of these three, the submersible is the best, in my book.
You can tell a piston pump by the
quiet, pleasant “thumpa-thumpa”
sound it makes. Most also include a
couple of visible rubber drive belts
connected to an electric motor
by exposed metal pulleys. Piston
pumps are great for shallow-well
situations with up to 91 metres
(300 feet) of horizontal draw, but
never for raising water more than
about six vertical metres (20 vertical
feet). Piston pumps used to be very
popular decades ago, but they are
falling out of favour because of their
high cost relative to pump output.
What’s so special about six metres
(20 feet) of vertical draw? That’s the
maximum depth that a pump can
draw water by suction. Any more
than this and the pressure drop
in the pipe will cause the water to
vaporize at room temperature under
the suction.