How Does a Water Powered Sump Pump Work?

A backup option to your primary electric sump pump is a water powered sump pump. Water powered pumps contain few moving parts and do not need electricity or a battery backup. As long as you have city water (not well water) you'll have a working sump pump and a dry basement—even if the power fails.

How a Water Powered Sump Pump Works

A water powered sump pump employs the Venturi effect. City water flows through a constricted area. At that constriction water speed increases causing a pressure reduction. This pressure reduction literally sucks water from the sump crock. Sump water then combines with the flowing city water and exits your basement via a discharge line.

Differences Between Electric and Water Powered

Electric and water powered sump pumps both evacuate sump water, but the electric pump is more efficient, cost effective and environmentally preferable. Both systems are affected by the height of the discharge line. The higher the discharge line the fewer gallons of water can be removed. To overcome this, electric pumps employ larger motors that drive larger pumps but water power requires more water pressure to remove more sump water.

Electricity is cheaper than city water. Environmentally both have an impact but pouring expensively treated water into a discharge line can only be acceptable in emergency situations like a power outage or electric pump failure.

Water Verses a Battery Backup System

The battery system must be checked periodically to be certain it is charged. Over time batteries must be replaced so they represent an ongoing expense to maintain and one more check box on an already full to-do list. During an extended power outage batteries will eventually run out of power and the system will fail. Water powered sump pumps will run as long as you have city water.

City Water Systems Only

Well water might be less expensive but if the electricity fails so does your well and so does your water powered sump pump. In homes that use a well, a water powered sump pump is not a good option.

Decision Points

Consider these points to evaluate water powered sump pumps:

  • Price versus cost. All water powered pumps require a valve that prevents sump water from entering your city water system called a back flow preventer. Does the model you are considering include this valve or must you purchase it separately?
  • How accessible is the city water main? To eliminate reduced pressure from normal water use in your home, such as flushing a toilet, you must provide a direct line from the city water source to the water powered sump pump. The further your sump is from this source the more the cost and level of installation complexity.
  • How much water do you need to move? Pumps are rated in gpm or gallons per minute. The higher the discharge line the less water the pump will move. Water pressure is also a factor. The more pressure your city system supplies (expressed as psi or pounds per square inch) the more water the pump can evacuate.

Use quality as your final decision factor. Peace of mind is a motivator for investing in a back-up system. Well rated pumps mean your chances of avoiding a water disaster improve. Buy the best you can afford.