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Water Supply (page 2)...

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Pumps

The type of pump that you need to pump water from your water source to your cottage is dependent upon several factors. A couple of important attributes of pumps is their suction lift (or suction head), and their discharge head. These terms refer respectively to the vertical distance the pump can suck water up from the source, and the vertical distance it can push it up further to where it is needed. The absolute vertical distance that pumps can suck up water is just under 33 feet, as they create a vacuum and rely upon atmospheric pressure to push the water up the pipe. Beyond a certain point, the atmosphere can't push hard enough to fill the vacuum. A realistic limit for suction pumps is around 25 feet. In the case of the discharge head, this also refers to the output pressure which will be needed to pump the water into a pressurized tank.


There are three types of pumps in general use:

Centrifugal Suction Pumps

Jet PumpCommonly known as a jet pump, this is a reasonably-priced pump that can be used where the water has to be pumped up from a vertical distance of no more than 25 feet (7 to 8 metres). The line to the water source will need a foot valve at the bottom end to prevent the water running back out of the line and causing the pump to lose its prime. When turning on the water supply in the spring, or after a prolonged absence, it may be necessary to prime the pump and the water line by unscrewing the metal plugs on the pump (but not the drain plug), and pouring water into the pump until both the line and the pump are filled and have no air in them. Replace the plugs and turn on the pump. It should start drawing water into your tank immediately. Here is an informative article on water well pumps (including jet pumps) from Popular Mechanics.

Piston Suction Pumps

Piston PumpThese are more expensive than centrifugal pumps, and one of their few advantages seems to be that they are more tolerant of sand in the water than other pumps. They also have a larger discharge head than jet pumps, even though the output discharge rate may be lower. Piston pumps do have an advantage if there is no source of alternating current electrical power available, as they can be adapted to wind power, manual cranking or direct current motors (driven by batteries or solar power). Like centrifugal pumps, you will need a foot valve at the bottom of the water line. Otherwise, for most people's uses, this type of pump does not have any significant advantages. I have also sometimes found it harder to prime than a jet pump. There is more maintenance required on them, too, as parts like gaskets, cup leathers, valve rubbers and springs, and packing rings need to be replaced every couple of years, and necessitate taking the pump apart. They also have a tendency to leak water when the packing rings around the piston rod deteriorate.

Submersible Pumps

Submersible PumpSubmersible pumps may be used where the suction head from the water level is too great for a suction pump, often because the well is deeper than 25 feet. A submersible pump is generally a form of electric centrifugal pump that is immersed in the water close to the bottom of the well. It consists of a sealed motor that drives an impeller which draws water into the bottom of the unit and expels it upwards through the water line to the surface. Depending on the model, the discharge head on these pumps will be sufficient to pump the water up the required vertical height. One major advantage of these pumps is that because they are immersed in the well, they will not freeze up, and, providing your water line is either heated or there is an automatic method of draining the water out after use, they can easily be used in winter. Various models of these pumps are available, and, generally, the deeper the well is, the more powerful is the pump that is required. Some models run on 240 volts, as they require the torque to either break up encrusted mineral deposits on the pump parts themselves, or to initiate the upward flow of water in the deepest wells. When installing a deep well submersible pump in a drilled well, it is best to consult a professional.

Hand Pumps

Pitcher Pump For occasional, winter or emergency use, a hand pump can have real benefits. There are a variety of types available, but for cottage use there are two basic models. These are the pitcher pump (so-called because it has some resemblance to a water pitcher), and the deep well hand pump (that looks like the old-fashioned hand pump found in barn yards for watering cattle).

The pitcher pump (as shown, above right) is a squat-looking pump that sits on top of the well, and has a suction head of no more than 20 feet or so. Some models are self-draining, and after pumping, any water remaining in the pump or the drop pipe gradually flows back into the well. This permits the pump to be used in winter without freezing.


Deep Well Hand Pump
Deep well hand pumps (right) can be used in wells up to 300 feet (100 metres) deep. The actual pumping mechanism (or cylinder) is immersed in the water at the bottom of the drop pipe, and is operated by the pump handle on the surface transmitting the pumping action to the cylinder via a rod down the centre of the drop pipe. Like the pitcher pump, the deep well hand pump can be operated in winter because any water drains out of the pump and drop pipe after use. The cylinder, however, must be fully immersed in the water, otherwise there is a possibility of it freezing up. When we had a new well dug, we had to extend the drop pipe and the rod inside it to make sure the cylinder was down far enough.

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© 2009, David Mallinson. --- Last updated 01-May-2014