Do you wonder what happens to the hot water that goes down the drain when you take a bath, a shower, or run your dishwasher?

Probably not! You likely have never even considered it, but the heat from your drain water is easily reusable.

New Brunswick is full of multi-level residential homes with three or more occupants. These homes produce (and waste) an incredible amount of hot water.

This article outlines what a drain water heat recovery (DWHR) system is, how it can reduce the amount of hot water you waste, and ultimately how it can help you save money on your hot water bill

What is a drain water heat recovery system (DWHR)

A DWHR system is an easy way to reduce how much energy is needed to heat your hot water.

These systems include a simple copper pipe wound around a vertical section of a drainpipe. In a typical setup, unheated water bound for your hot water tank flows through the copper coils before reaching its destination.

The hot water in the drainpipe works to heat the copper coils and heat the cold water moving through the copper coils.

Because the water bound for your hot water tank is already pre-heated, a DWHR system can reduce the energy required to operate your hot water tank.

How a drain water heat recovery system works

How a drain water heat recovery system works

Your hot drain water moves down the drainpipe as usual, and the cool water bound for your water heater flows through the hollow copper pipes. The copper piping will absorb the heat from the hot drain water and transfer the heat to the cold water within the copper piping.

Remember the drainpipe and the heat recovery coils are separate from each other. Copper is a powerful conductor of heat, so while the heat is easily transferred from the drain water to the cold water on its way to your water heater - the actual water never mixes.

Drain water heat recovery systems are ideal for single-family homes with heavy water usage or heavy drain water events.

A drain water event is when a significant amount of hot water is used and drained while concurrently pulling a substantial amount of cold water to re-fill the hot water tank (such as a shower). 

It is in these cyclical scenarios that homeowners will see the benefits the most.

The benefits of these systems

It sounds easy because it is! Drain water heat recovery systems do not include moving parts, do not need to be powered by battery or electricity, and have a long lifespan.

Alongside these points, look at how a DWHR system can benefit you:

  • Save on energy. A DWHR system can save an average New Brunswick household as much as $150 per year. The savings will vary based on how many showers are taken per day (and how long they are).
  • Preserve the life of your water tank. When you take advantage of the hot water in your drainpipe and reuse it to heat water, you are putting less strain on your hot water tank.
  • Enjoyable shower usage. No more running out of hot water! With a DWHR system in place, your household can enjoy up to 3 times more hot water.

Best of all, a drain water heat recovery system is versatile. These devices are compatible with homes with solar powered water heat sources, a tankless water heater, or a hot water tank. Expect to pay between $800 and $1,500 to purchase a system and have it installed by a plumber, but the savings can be worth it!

How these systems save residents money

DWHR systems work to save residential homeowners money by reducing the energy required to heat water. In essence, the copper piping allows you to recycle the heat already generated.

But this is not the only way that New Brunswickers can save money by installing a DWHR system. NB Power offers incentives of $200 to $400 towards customers who purchase a DWHR system.

For example, if you install a DWHR system with two or more primary upgrades, this may increase your incentive return.

Final thoughts

A DWHR system may not be the most glamorous of upgrades, but the beauty is in its simplicity! This simple addition to your drainpipe can provide impressive energy-efficient savings.

Have questions about energy-efficient upgrades? Check out the NB Power Total Home Energy Savings program to check your eligibility, register, and discover what upgrades are best for your home!


How much does a drain water heat recovery system (DWHRS) cost?

The cost of a DWHR system ranges between $800 and $1,500 including purchase and installation. You can install it yourself if you have the know-how, but it's recommended to have your DWHR system professionally installed by a licensed plumber.

What is drain water heat recovery?

Drain water heat recovery is the recapture of heat from used hot water moving down a drainpipe.

What is the payback of a drain water heat recovery system?

Provided that you have a single-family home with occupants who take frequent showers, an average New Brunswick household could save as much as $150 each year.

How does wastewater heat recovery work?

Heat recovery works by winding hollow copper piping around a vertical drainpipe. The copper will capture the heat from the wasted hot water travelling down the drainpipe and transfer it to water flowing through the copper piping. It will then carry the heated heater to the hot water tank or other plumbing fixtures for immediate use.

Is a DWHRS a good investment for my family?

Absolutely. NB Power offers incentives towards DWHR systems for customers who take advantage of the Total Home Energy Savings program. Not only does it save money on your energy bill, but you may be eligible to receive more money back!