The Right Pump For Rainwater Harvesting

Water is the life-blood of the world yet often taken for granted.  We assume that water is plentiful and the supply is endless because it is one of the most inexpensive natural resources we can buy.  It's easy to believe that the water supply will always meet the demand, so long as you don't consider the areas that suffer for lack of this precious resource.

 

Many of the water cisterns we see today are old and in disrepair, but the production of new and more modern water tanks is encouraging for those of us concerned with water conservation.  Reservoir tanks don't necessarily need to be hidden from view; some even offer aesthetic additions to the home landscape.

 

 

The preference to hide the holding tank prompts many to place their reservoirs underground.  While this is as good a way as any to catch and store water, it doesn't provide for a gravity flow dispersal of the water, which saves on electrical usage.  The pump is a convenience in any system, but it is the most expensive part of the system after the cost of the holding tank.

 

 

The pump for a rainwater harvesting system needs to be rated specifically for the job it is required to do.  Some installers don't take this into consideration and install an oversized unit.  This is an important part of the price quote and the horsepower of the motor should be specified.  If the pump motor is too large for the application, the owner has to pay more than necessary for it, and a pump that is too large will wear out faster than one that is properly sized.

 

Adding insult to injury, some installers use the wrong type of pump for the system.  The common well pump is not designed for use in a rainwater harvesting system.  Keep in mind what a pump does.  In the case of a well pump, it may be submerged and have to push the water from deep within the ground.  A sprinkler irrigation pump pushes water too, but not from deep within the ground.  The rainwater harvesting pump may need to be designed to both pull and push water.

 

In a buried storage tank application, water will not be coming from deep within the ground, so if it must be pushed, it won't take as much force to do so, and the elevated tank will require very little pull.  If energy usage is going to be minimized in the process of water conservation, the pump must be of the right size and type to do the job properly.