EcoDrain recycles the heat in used hot shower water


July 7, 2014

The EcoDrain uses outgoing hot water to heat incoming cold water

The EcoDrain uses outgoing hot water to heat incoming cold water

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Generally-speaking, when there's something that we're trying to conserve, we don't just put it down the drain. For those of us who are trying to save power, however, that's just what happens when we let hot water from our showers or baths run straight into the sewer. The EcoDrain is made to address that problem, via a unique design that allows outgoing hot water to warm up incoming cold water.

First of all, there are indeed other drain heat exchangers that do the same basic thing – they absorb heat from the used hot water, and deliver it to the about-to-be-used cold water. Although that incoming water probably still won't be warm enough to bathe in on its own, less hot water will need to be mixed in with it, thus saving power.

In the case of most of those other systems, however, they need to be located along a relatively long stretch of vertically-oriented drain pipe. Not all existing homes have such a setup, meaning that the heat exchangers can't be installed in those homes ... or at least, not without a lot of work.

The EcoDrain, by contrast, can be installed horizontally. This means that it could go under the bathroom floor immediately adjacent to the drain, thus catching the waste water at its hottest.

It contains no moving parts, requires no electricity, and takes the form a double-walled pipe – it's a pipe within a pipe, really. Incoming cold water runs through the inner pipe, while the outgoing hot water runs in the opposite direction through the outer pipe, completely surrounding (but never entering) the cold one. This means that the cold water pipe gets heated from all sides by the hot water.

Additionally, in order to allow more of the cold water to be exposed to the warmth, a series of baffles in its pipe create turbulence in its flow. This keeps it from just shooting straight through, with only the outside of the stream getting heated.

The EcoDrain has been in development for several years, although its designers inform us that it received US building code approval just last December, and was officially launched within the past few weeks. It's priced at US$439.95, and is claimed to offer a return on investment ranging from 17 to 43 percent per year – based on the energy costs in various American cities.

Looking at it another way, the company also claims that installation of the EcoDrain will let you shower for 33 percent longer, using the same amount of power that you would have used without it.

More information is available in the video below.

Source: EcoDrain via Treehugger

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Since the current trend is to use less water, with more efficient showerheads etc, plus more households are using solar heating, I'd like to see the warm waste water being diverted into radiators throughout the house, to use solar power to warm the house.


Great idea but that price tag takes the green out of my wallet.

Mark A

Doesn't appear to use any heat pipe technology as such, though that would help.

In reality, if you drill two channels through a solid aluminium block, and thread both ends, you could make one of these contraptions.

Just have to insulate it appropriately. The concept obviously only works if you put it on the incoming to your heater unit. Though how this can be done economically is the next thing, as you would either bring the drain to the incoming feed or vice-versa. Probably the latter. A lot of plumbing. To be undertaken on a new build, or a raised house without concrete foundation so you can get at the pipes. Will put it on my list of projects :)


It's a simple idea apparently done well.

However it shares the main disadvantage the existing products have. And that is a ridiculous price for something that you can make yourself for less than $100 in plumbing parts.

Like the others, they're gouging simply because the individual home owner/ handyman can't ameliorate the certification cost across multiple units.

Mark C

Seems a lot of effort to recover very little energy - showers are meant to be relatively energy/water efficient anyway (unless a power shower!).

Might be better to look at recycling the used water into the same shower, after the first soaking the waste water becomes relatively clean with some filtering and remixing with fresh. Perhaps a recycle switch for when you are just enjoying the water showering on you rather than washing!

Brian M

This idea is good, but the price of this device is very hight.

In Brazil, the people use electric shower and a company called REWATT made a simple device that recover the heat and use it imediatly in the shower.

The address for this company is and it is not expensive like that.

Jose Americo

This is most effective for households of 2, 3, or more who take long, hot showers every day. There are far better and cheaper ways to save energy by modulating its use more efficiently.

Nuff said.


two things:

One can get the same thing done for under $100. for sure!!! - that price tag is ridiculous!!!....what is the dude smoking???? (use outer PVC and inner copper tubing)

The idea is to use LESS water....not: "..will let you shower for 33 percent longer, using the same amount of power that you would have used without it."

-no mention of the wastage of water here in the additional 33%!!!

Then again....I live is a very dry part of South Africa where each drop of water is appreciated.


So how does the unit cater for clogging by materials such as hair, sud, etc? which will accumulate with time. And the price...come on...nobody in their right mind would buy this if you can quite easily make it with local plumbing stuff..... What if the system was turn on its head - Hot water pipe within a larger cold water pipe with say a 5-10mm variance in the large outer pipe diametre????

You have the hot, waste water flowing through a COPPER pipe within a larger diametre AL -PEX pipe where the fresh cold water is sent to the shower under normal municipal pressure. The heat will dissipate from the hot waste water via the copper tubing it is travelling through into the the cold water passing in the opposite direction and as a result of the inner AL-Pex piping having a layer of plastic making it a poor conductor of heat, the cold fresh water will warm up as it heads to the shower. The catch however, is what length of time and exposure is necessary for the cold fresh water to be heated to any significant level? There is an entry point and exit point for the fresh cold water within the larger pipe surrounding the inner waste pipe. Guess mixing of the water and should the waste water clog - just power drain it and wha La...system is good to go again!!!


that return on investment has to be wrong way wrong

i doubt it would pay for itself by the time it wore out

you also have to pay for the more complicated installation

and replace when it starts leaking in about 8 years



also, if you don;t USE much hot water, this thing can;t save much energy

so to have it pay off, you have to be a water waster to start with




In addition to the high price problem, you have an even bigger problem if the drain pipe has to be cleaned.

There are baffles inside the drain pipe.


Nice idea, but I accomplish this without spending any money.

I close my drain, take my shower and leave the hot/warm water from my shower in the tub.

Once it cools, I open the drain and let it into the sewerage system.

And my cat knows enough never to go into the tub until it's drained.

Mark Markarian

Made one of these out of scrap copper pipe. The heated cold water goes straight to the cold water side of the shower. As the shower temperature is controlled by a thermostatic block it adjusts to the new warmer cold water coming in. Simple and cheap.


Boy do I hate having to read all the naysaying!

On the other hand I agree with all: High cost, little return, drain clog issues

You would need one at each shower point so after two points you could rather spend the ~$1000 on a simple solar heat exchanger type water heater which actually would save energy without using more water.

In Arizona we like the ideas that conserve water, not encourage us to use more.

The list of items I would buy before this is so large I cannot ever imagine actually buying this device.

Dr. Veritas

So what is new about this ? I had an option of such a heat exchanger for my Kreonite photo processor some 40 years ago !


The best place to put devices like this is near the water heater, with the cold supply line to the heater running around a large pipe for the drain water.

That way all the hot and warm drain and sewer water flows through and slightly warms the cold water going to the water heater, reducing the amount of energy required to bring the tank of water up to temperature.

The drain part of any of these gizmos should be straight and clear so nothing can catch and clog it.

Gregg Eshelman

This would be useful for cycling a lot of people through the shower 33% more hot shower time might mean that the last guy gets hot water. A real improvement in efficiency would be for a refrigerator manufacturer to make a refrigerator that dumped the waste heat into water heater.

@ ASHDIL Some places have plenty of water. Saving water in New Orleans is not going to help LA.

@ robo The baffles are in the cold water pipe. But I agree the drain pipe should be indistinguishable from other drain pipe from the inside.


(Full disclosure: I have done work for ecodrain in the past but was not asked – nor am I being paid – to post this comment.)

Getting a drain water heat exchanger to work horizontally and efficiently is not trivial. Ecodrain performed thousands of experiments and iterations to make sure it works extremely well (and won't clog). If you are interested in details, see the "Our Story" section of their website.

In terms of value, I think it's reasonable – not only in terms of the cost of the raw materials (it contains a significant amount of copper) but also in terms of ROI. As an energy-saving investment, it's way better than solar panels. According to, a rooftop solar array (cost approximately $20K) in California – one of the better places to install solar panels – provides a return of 12%.

Installing an ecodrain will typically provide between 17% and 43% return. However, it can be much higher – in one case a family of 7 estimated their payback would be less than a year (over 100% annual return).

I guess what you do with the savings is up to you.

Gregory Kalinin

as others have pointed out: hair & baffles = future expense. some form of pre-filtering ought to be implemented


Good idea but rather expensive and large. We learned rather quickly in our motorhome and travel trailer days how to take fast energy efficient showers with as little as one and a half gallons of water with a hand held flexible shower head. At home we use a water conserving shower head which uses little more if you shut off the water between wet down, soap down and rinse down cycles. The same hand held camper type shower head can be attached to most home showers. This may not reclaim the heat that is lost but it saves huge amounts of hot water and actually gives a better shower. The true key to conservation is to never use more of anything than you really need. A long hot shower is rapidly becoming a luxury that we can't afford. Anyone looking to live off the grid should begin by studying the RV industry. Many energy conserving ideas and techniques have already been developed and many can be converted for home use.


The "baffles" are on the cold water intake channel so... there is no hair to contend with.

Gregory Kalinin

Actually, it's designed not to clog, as answered in the FAQ:

"Ecodrain has been designed to optimize drain flow and to prevent any materials from getting stuck.

Watch as a large clump of hair easily passes through the ecodrain:"

(A gif demos it here at

Paul Smith

to Slowburn, so you advocate for wastage????....just because you may have plenty is no excuse for wastage...its about doing the RIGHT thing Dude!!!!...common sense should be the order of the day, I think.

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