Hot Water Recirculation Systems

Stop Waiting & Save Water
If you are tired of letting water flow down the drain before hot water arrives at your faucet or shower, there's a solution. A hot water recirculation pump can be installed that will provide hot water almost instantaneously upon demand. The United States Environmental Protection Agency (U.S. EPA) estimates water savings to be nearly 10 gallons per day, or 3,650 gallons per year (US EPA Study). Water savings will vary depending on the type of recirculation system installed, number of people in the household, and pipe length from the water heater to the farthest fixture.
Typically, in a one-way plumbing system without a recirculation pump, water is simply piped from the water heater through the pipes to the tap. Once the tap is shut off, the water remaining in the pipes cools, which then requires the faucet to run until the cold water in the pipe is pushed out and the hot water from the water heater arrives at the faucet.

How Hot Water Recirculation Systems Work

Hot water recirculating systems work by circulating the water sitting in the hot water line (that has cooled) back to the water heater and replacing it with new fresh hot water from the water heater. This is done in seconds with a pump eliminating the need to wait for hot water.
Some Hot Water Recirculation Systems pump the water sitting in the hot water line (pipe) back to the water heater through the cold water line. Therefore, water sitting in the cold water line could have originated in the water heater. So, if you then drank a cup of cold water, that water may have originated from the water heater. Generally it is not recommended to drink water from the water heater or the hot water lines because hot water can dissolve lead and other metals more quickly than cold water.  This can be an issue in older homes which may have lead in the pipes,  pipe solder or in the valves and fittings. Generally if the Hot Water Recirculation System is used to get hot water for showering only, this should not be an issue. However, when determining if a Hot Water Recirculation System is right for you, consider hot it recirculates the water an d how you will be using it.
Systems Available
There are a variety of systems available, but the On-Demand Systems are the best for homes.

On-Demand Systems
On-Demand Water Recirculating Systems are the most water and energy efficient recirculation systems, and only work when you want hot water. The hot water on demand pump is activated instantly by pushing a button which activates the pump for several seconds to pump hot water from the water heater and sending the cooled water back to the water heater through the cold water pipes. The pump then automatically shuts off when it detects hot water flowing through it, requiring minimal energy to run the pump, and energy use is limited to the initial pumping of the hot water from the water heater. This is the best type of system for a home.

Full Time Pumps
Full time or continuous recirculation pumps continuously recirculate hot water in a loop from the water heater to the fixtures. Although this system delivers hot water to the fixtures without the wait, this system has high energy use as the water heater needs to work harder to replace the energy being constantly lost through the pipes. This system might be found in a hotel where hot water is in demand 24 hours a day at the fixtures. We do not recommend this type of a system for a home.

Install a Timer
Installing a timer on the hot water recirculation system to come on only during certain times of day can reduce energy loss, as the system is not operating continuously. However, operating the system outside the timer's operating hours will again result in waiting for hot water and wasting cold water, and every hour the system is operating it is losing energy. We do not recommend this type of system for a home.

Control Water Temperatures
Water temperature can also be used to operate/control hot water recirculating pumps. These systems will turn on and recirculate water when the temperature in the hot water line drops below a specific temperature. Although they do not use as much energy as a continuous recirculation pumps, they will come on regularly to maintain a specific temperature.  We do not recommend this type of a system for a home.

Find Out More
The following links are to manufacturers of On-Demand Hot Water Recirculating Systems. Please note, CCWD does not recommend or endorse any of these companies or the products they provide, but rather, provides this information as a resource to customers interested in eliminating water waste through the hot water recirculation technology.
Additional Resources & Information for Hot Water Recirculation Systems
  • Hot Water Distribution Guide U.S. EPA WaterSense
  • CUWCC PBMP Residential Hot Water Recirculation System
  • Alliance for Water Efficiency Hot Water Distribution Introduction
  • Water and Energy Savings using Demand Hot Water Recirculating Systems in Residential Homes