Bison Pumps offer two basic types of pumps: shallow well and deep well. When we are designing your pump system, this is the first decision our team must make. Here we are going to discuss the Shallow Well Pump.
Highlights of a Shallow Well Pump
- Water source vertical distance to the pump water inlet cannot exceed 25 feet.
- Water source horizontal distance to the pump water inlet is at a maximum 200 feet but can be less.
- Flexible hose can be used instead of pipe to connect the pump to the water source.
- Multiple water sources such as tank/cistern, pond or creek can be used.
- Pump body is subject to freezing if not winterized.
A Shallow Well Pump is also known as a suction pump. This is due to the movement of the water through the pump being accomplished by creating a vacuum, or suction, to draw the water from its source to the pump inlet.
These pumps consist of a body, water inlet, piston assembly, handle and spout. To access the water source, a pipe or flexible hose is connected to the water inlet. The handle moves the piston up and down. On the down stroke, the piston moves through the water which flows through the inside of the piston bypassing the one-way check valve located inside the piston. Once the piston is at the bottom of the pump body, the water is located above it. Next, you move the handle down which raises the piston assembly. Below the piston a vacuum is created which draws water through the water pipe/hose connected to the water Inlet of the pump and inside the pump body. This water flows through a different one-way check valve in the bottom of the pump body filling the pump body with water below the piston. The water above the piston is raised up to the spout opening where it flows out the spout. This process is repeated to generate a flow of water from the pump.
What you will notice from the above description is that the water enters the pump due to the vacuum created by the piston movement. This vacuum’s ability to draw water is limited by physics to roughly 25 feet below the mounting location of the pump body. Technically, the distance is 31 feet minus the water friction in the pipe, any leakage in the pipe system, and one foot reduced for each foot above sea level. The industry has settled on defining suction pump functionality at 25 feet. While our pumps can draw from deeper than that, it depends upon each customer’s situation.
The other thing you will notice is that water remains in the pump body at all times. These pumps are installed above ground and therefore, if exposed to the elements, can freeze. This is why these pumps must either be installed in a climate that does not normally freeze, in a climate-controlled environment (inside a home or a heated well house for example) or with a Drain Back Feature. With the Drain Back Feature, the pump system can be completely drained of all water above and below the piston. However, some moisture will remain that will freeze though not damage the pump. The pump handle cannot be moved once the pump has been drained which would cause damage to the internal workings of the pump. The shallow well pump will be unusable while in this state until the weather has warmed to a level where freezing is no longer a concern.
View the pros and cons of a Shallow Well Pump compared to a Deep Well Pump System.