How Ecodrain Works

What if you could capture some of the heat of all that hot water that goes down the drain? See more green science pictures.

You may have already started shortening your showers to conserve water, but have you ever thought about just how much energy is escaping down the drain every time you shower? One Canadian company has thought about it, and has come up with a unique solution. It's called EcoDrain.

When you take a shower, the water moves quickly from the showerhead over your body and down the drain. Because of that speed, the water doesn't lose much heat and ends up running down the drain while it's still warm. Meanwhile, cold water enters the system to replace the water in the shower, and it needs to be fully heated by the home's water heater.


EcoDrain is a group of heat exchangers that recapture the heat that's lost through shower drains. It uses the warmth from the water running down the drain to heat the cold water before it enters the shower. That means that the hot water heater doesn't have to work as hard, less energy is used, and theoretically, energy bills are lower.

Keep reading to learn how to install EcoDrain, and how much energy it might save in your home.

Water's heat doesn't all have to be lost.
Water's heat doesn't all have to be lost.

EcoDrain is a small device containing heat-exchange channels. These channels move the heat from warm water running down the drain to the cold water running into the water heater or shower mixing valve.

EcoDrain works with most tankless water heating systems, and the same system can be used for all the showers in your house (provided everyone in the house doesn't decide to take a shower at exactly the same time). It shouldn't affect shower pressure; however, there is a limit to how much water can flow through the system.

There are two types of EcoDrain: vertical (the Upright) and horizontal (the Sleeper). Which one you use depends on the pipes in your shower. The Upright model works only on vertical pipes, while the Sleeper works on either horizontal or inclined pipes. Other types of EcoDrain are in development.

The system is installed under the floor of the shower, and connected directly to the shower drain line. Although EcoDrain is easy to install, it's a job best left to a plumber or contractor.

The EcoDrain can be set up in one of three ways:

  • Connected directly to the water heating system
  • Connected to the shower mixing valve
  • Connected to both the water heating system and the shower mixing valve

The third option saves the most energy, because it preheats water that enters both the water heater and shower. However, it also requires the greatest amount of installation and equipment.

This is how EcoDrain works: As warm water leaves the shower, clean, cold water circulates around it. Inserts called turbulators increase the rate of heat transfer by generating turbulence in the water.

Don't be alarmed about your dirty shower water mingling with clean water from the pipes. The dirty and clean water come into close proximity, but they never mix because there is a double wall separating them -- the warm water simply transfers its heat to the cold water. Even if a hole were to form in this wall, the dirty and clean water would still not mix, because EcoDrain contains a vent that would send the dirty water harmlessly to the outside of the building.

Showers are the biggest home energy drain, according to EcoDrain. They consume up to 80 percent of a home's total energy [source: EcoDrain].

How much energy this system can save depends on several things, including the type of EcoDrain installed, how often the shower is used, the shower temperature, the temperature of the original unheated water, the type of water heater in use and the fuel cost. Based on these variables, EcoDrain can reduce hot water heater use by 20 to 70 percent [source: David Velan].

The shower is an efficient place in the home to reclaim energy, because water speeds down the drain without losing much of its heat. Compare that to a washing machine or dishwasher, which pull in water and let it sit and cool before draining.

EcoDrain is economical when installed during new home construction or bathroom remodeling projects because the pipe is already exposed. Installing it in an existing bathroom gets more expensive, however, because the bottom of the shower needs to be opened.

The EcoDrain system is virtually maintenance-free. Inside is a nonstick coating that prevents hair, soap, or other shower detritus from getting stuck, so no cleaning is required.

For information on where to buy EcoDrain, visit this site.

Related HowStuffWorks Articles


  • Dvice. "10 best ideas for greening your home that you've never heard of."
  • EcoDrain.
  • Green, Hank. "Stop Pouring Hot Water Down the Drain!" EcoGeek, March 23, 2009.
  • Inhabitat. "The EcoDrain Cuts Water Heater Use by 40 Percent." March 23, 2009.
  • Personal correspondence with David Velan, manager of EcoDrain, July 6, 2009.