Water Conservation - No Waste Reverse Osmosis Water Purification System

What is a zero waste reverse osmosis system?

Reverse osmosis systems squeeze water through a membrane that lets water through but the contaminants can’t pass through the membrane. The contaminants that are filtered out need to be flushed away from the membrane for the system to work properly. Reverse Osmosis (RO) systems typically flush down the drain 3 to 15 gallons of contaminated water for each gallon of clean water they produce.

From a water conservation point of view this is very inefficient. Watts has come up with a new RO system that recycles the contaminated waste water, eliminating the need to flush contaminated water down the drain.

Watts Premier "Zero Waste" ZRO-4 Reverse Osmosis System

The Watts patented ZRO-4 Reverse Osmosis System is the first system that does not waste water any water. The new Watts RO system simply pumps the contaminated water into your water heater.

The presumption is that it’s ok for the contaminated water is ok to bath in and wash your hands, dishes, and clothes in.

A small pump is connected in series with the membrane unit and they are in turn connected to the cold and hot water supply pipes. When the RO unit is operating the contaminated water from the input side of the membrane is slowly pumped into the water heater through the hot water line.

The instructions say to locate the ZRO-4 RO system at least 25 feet from the water heater. I wish they would tell us why. What happens if it is closer to the water heater? Is it an energy related thing? Is it to keep the contaminated water in the piping, hopefully to be purged when somebody draws hot water and thus not end up stored in a hot tank? I would really like to know.

Does it work with tankless water heaters?

I don’t know. I could not find any information about operation with tankless water heaters, but I presume it would still work. I see no physical reason why there would be a difference. But then there is that 25 foot distance from the heater thing. Does that still apply? Perhaps with tankless hot water you don’t need the 25 foot distance.




Will it work with a Hot Water Recirculation System?

Hot water circulating, often called recirculating systems and or recirc pumps come in several varieties these days. Some are simply hot water circulating systems with dedicated return lines for the hot water circulating loop, and some systems use the cold water return lines for the loop return.

If your hot water system has a recirculation system with a dedicated hot water return line then there should be no problems. However, if you have a system that uses the cold water line as the return then there will be some problems.

The pump for the circulating or demand system causes water to flow through the RO unit as though it were running whether or not it is running at the time, which can slow down the delivery of hot water from a demand hot water system, and can potentially end up putting contaminated cooled off hot water in the cold water lines.

The warm water circulating systems will also end up allowing contaminated water into the cold water piping.

A solenoid valve is incorporated into the retro-fit version of the zero waste system in series with the pump. The valve may prevent the circulating systems from pushing water through the RO system and thus solve the problem but I have not tested it so it’s just a maybe at this point.

What are the contaminants that the Watts ZRO-4 removes?

The Watts ZRO-4 reverse osmosis system reduces Arsenic (V), Cysts, Cyrptosporidium, Giardia, Entamoeba and/or Toxoplasm, Barium, Hexavalent, Chromium, Trivalent Chromium, Copper, Lead, Fluoride, Cadmium, Radium 226/228, Selenium, TDS, and Turbidity.

Motion Sensing for Residential Hot Water Demand Systems

Using a motion detector to start your hot water demand system can have unexpected results.

Demand systems are meant to be activated and then used quickly. Hot water in your piping cools off quite rapidly. Since a demand system shuts off the pump when hot water reaches it, if you don’t use the hot water quickly it will soon become “warm” water and to get hot you will still need to run more water out of the pipes and down the drain.

How the hot water demand system behaves a short while after being used depends mainly on how long since the system was last used. If the water hasn’t cooled to below 96 degrees the pump will be locked out and won’t start until the water in the pump cools to below 96 degrees F. You will be forced to purge the warm water from the pipes to obtain hot water and end up running that water down the drain.

If the water has cooled to just below 96 degrees… say about 90 degrees, then the pump will run again until it sees a sudden increase in temperature or if it senses water hotter than 96 degrees and then shut off again. Now however, there will be 90 degree water filling the cold water line.

If you begin using the hot water mixed with cold, after a short time the warm water will be purged from the cold water line and you may need to re-adjust the temperature to add more hot and less cold water. More details about how the hot water demand system behaves in different situations. It pretty much depends on the water temperatures in the piping.

Using a Motion Sensor

As you can see, any significant wait after you have tripped the motion sensor can cause an inconvenience and or end up wasting water.

Another thing to consider when using motion sensors to control your demand system is what happens when someone enters the bathroom while you are taking a shower? Depending on your plumbing layout and how long since the pump was last run, it could cause a fluctuation in water temperature like flushing a toilet sometimes does.

This is especially true when you have a tankless water heater. Since tankless water heaters take time to heat the water, typically 10 to 20 seconds, if the heater has been off for a few minutes you may experience a brief “cold water sandwich”.

Before you decide you want a motion sensor to activate your demand system you might consider how often you enter your bathroom when you don’t want hot water. Each time the pump runs and you don’t use hot water you are wasting energy and increasing your water heating bill. This is especially true with tankless water heaters. It doesn’t take many firings of the heater to use more energy than a standard tank type water heater loses in standby loss.

The same things hold true when using a timer based system. You can have the demand pump turn on automatically at say 7:30 a.m. every morning, but if you push the snooze button a time or two you are still going to need to run the pump again when you get to the bathroom.

Since the piping is warm you will get hot water faster but you pay the price in extra energy consumption.

For some people motion sensing to control the delivery of hot water is a welcome convenience, but for many others it would just be a wasteful nuisance.

Hot Water – Residential Hot Water Conservation Products

Hot Water Conservation Is Harder Than Cold Water Conservation

Water conservation products for cold water conservation are prolific. There are low flow fixtures; actually these are now mandatory in most areas, low flow shower heads, water conserving appliances, low flow toilets and other flow restricting devices.

There are also things like dual-flush toilets, toilet dams, drip irrigation systems, and all sorts of other water conservation products.

A lot of these conservation devices do not really provide conservation for those individuals who are already practicing good water habits. For instance, low flow kitchen faucets only save water when someone leaves the water running based on time. Filling the sink takes the same amount of water no mater how slow the flow is. The same is true with filling a pitcher of water.

Water conserving appliances often need the user to use special cycles, which are often not used.

Most of these water conservation products do not address one of the largest wasters of water in the home… the hot water plumbing layout. Long pipe make for long delays in getting hot water. Low flow fixtures make the problem worse by slowing down the hot water.

Slow hot water loses more heat energy to the piping as it moves toward the fixture, thus the wait becomes even longer and more water gets run down the drain. So what can we do?

Water Heater Pumps

There are a class of water heater pumps known as hot water demand pumps. These are small pumps that mount under the sink furthest from your water heater. When you want hot water you demand it by pressing a start button. When you push the button it starts the pump which pumps the hot water from the water heater to your fixture at high speed.

When hot water reaches the pump, an electronic controller shuts the pump off. Now when you turn on the faucet you get instant hot water and no water was run down the drain.

The pump uses the cold water line to return the cooled down hot water that was left in the piping from the last use back to the water heater inlet. They use very little energy to operate since they run for a very short time and only when hot water is demanded by the user. Typically they consume about $2.00 per year in electricity for a family of four.

Solar Water Heaters

Demand hot water systems work fine with all types of solar systems. Some types of solar systems have longer than normal hot water distribution lines and demand hot water systems are particularly good for those types of systems. It’s not what type of fuel you use free or not, it’s how long the distribution piping and how long a wait it is before you get hot water. The longer you have to wait, the more water you are running down the drain.

Tankless Hot Water Heaters

Demand hot water pumps work great with tankless hot water heaters as long as the demand system pump has enough power to turn on the water heater. Tankless water heaters take 10 to 20 seconds longer to get hot water to the fixtures than a tank type water heater. This makes the demand system that much more valuable with tankless units.

Hot water conservation with a demand system not only provides significant water savings, but it does it in a way that adds the convenience of fast hot water. This makes it much more likely that the user will actually use it, and water conservation will actually take place.

Recent Article: Residential Hot Water Conservation

Solar hot water

Tankless water heater Installation

Hot Water Recirculation

Tankless Water Heater Savings

After my last blog, I got an email from a friend of mine, who is involved with the installation and sales of tankless water heaters. Here is what he wrote:

Bill,

I read all of your blog interesting but very negative on tankless, don’t agree with all of it but well written. where are the heating efficiencies, for example tank water heater is only 40 to 55 % efficient vs. 82 to 94% how about the clean water you get without all the junk from the tank, I have attached a picture from a tank that was only 10 years old, take a look. LOL. At the end what is more costly and important 10 to 20 sec. Additional delay of getting hot water and may be 2 gallons of water or the inefficiency of the tank water heater and the additional energy wasted and environmental impact. Oh well, I could go on. LOL

Al


So in response to Al’s email…

First off, who has a 40 to 55% efficient water heater?
I poked around on the internet looking at water heater efficiencies, and could not find any water heater with an energy factor of less than .56. Most were .60 or more. (I presume we are talking about the energy factor when we refer to efficiency.)

I took a look at the tankless water heater specs and I found that most tankless units had energy factors of about .82. The highest I saw was .92, but I didn’t spend a lot of time looking so I probably just didn’t come across those .94 units.

So before moving on, I would like to say that using 40 to 55 percent efficiency for tank type water heaters is on the extreme low side. 60 percent efficiency would be the most common storage efficiency from my limited research.

I visited the ACEEE – (American Council for an Energy-Efficient Economy) who I think you could say is an independent 3rd party. They have a comparison table comparing Life-Cycle costs for the various types of water heaters.

Interestingly they recommend looking for a gas storage water heater with a minimum energy factor of .63 and they state that the highest is .67. Quite a bit higher than 40 to 55%.

From their table, a conventional gas storage water heater with a EF of .60 has a yearly cost of $350, and a tankless water heater with an EF of .80 has a yearly cost of $262.

As you can see the difference in yearly energy cost is 350 – 262 = $88.00 a year, or about $7.33 a month. A tad more if the efficiency was .82 as I was finding.

For me, $8.00 a month is definitely not worth the potential problems associated with tankless water heaters, and the changes in behavior I would have to make, like giving up that “trickle” of warm water I use when I brush my teeth. I hate cold water on my teeth!

As for the pictures of the corroded old water heaters… here are my thoughts. First, since I usually drink cold water, I am drinking the water from the water main. Since the water passing through the water heater also came from the same source of water, then it must be even cleaner than the cold water if it leaves all that stuff in the heater.

All that sediment and those deposits are just minerals that have come out of the water as it was heated, and you consume those same minerals every time you drink the cold water. So I don’t see a problem.

By the way, in areas with high mineral content many of the tankless water heater manuals instruct you to clean out your heat exchanger periodically. It seems the hard water is hard on tankless heaters too! Cleaning the heat exchanger on a regular basis does not sound like something I would want to do.

Metlund D’mand systems, our main competitor and the big guys on the block as far as sales go state that the savings from a demand hot water system from reduced water consumption and reduced sewage fees amounts to about $150 a year for a typical home with a natural gas water heater.

Gee… that’s more than the tankless water heater saves to begin with. If Scottsdale Arizona is offering rebates of $200.00 for homes that install demand hot water systems they must feel that the wastage of water from residential hot water plumbing systems is significant.

If you are really concerned about environmental impact, then you should put a hot water demand system on your tankless unit and more than double the monetary savings and reduce both energy consumption and water wastage. Pumping and treating water and pumping and treating sewage consumes energy as well.

Subtract that extra gallon or two of water from the savings provided by the increased efficiency of the water heater, and environmentally the tankless water heater doesn’t look so good. Just my opinion of course.

So Al, perhaps I have miss-interpreted your numbers, perhaps you weren’t referring to energy factor with your efficiency numbers?

That’s all for today folks…LOL…if anyone reads this blog.

Bill

All About Hot Water

Ok, this is my first official blog. I was hesitant to start a blog since I wasn't sure I could come up with something to blog about often enough to make it worthwhile, but I figured out what I could do if my brain was too slow.

Publish some of the more interesting emails we get from potential customers, and my response to them. We get all kinds of emails from people who don't understand one thing or another, and I have to assume a lot of them don't read either. If they did they would have found the information they were looking for right on the front page in many cases. LOL Go figure.

Hot water... the last frontier.

In a way hot water is like the final frontier. It seems like every other way to conserve energy and water has been covered many times over. Low flow everything from toilets to shower heads and high efficiencty appliances like dishwashers and washing machine are now common place.

Now maybe it's time to address the enourmous amount of wasted water and energy that could be saved from our hot water plumbing distribution systems. Todays large homes tend to have long and large diameter hot water piping which leads to a great deal of water being run down the drain, and heat energy slowly disspating from the pipes full of hot water sitting there cooling off.

Conservatively a demand hot water pump like the Chilipepper can save a typical family of four over 10,000 gallons of water per year. With over 50 million single family homes in the United States, if everyone had one of these systems we would save over 500,000,000,000 gallons of water per year. That doesn't count condos apartments and commercial uses if applicable.

It's very inexpensive and typically will pay for itself in a couple of years. In addition, the home owner gets his hot water faster which is always nice.

The demand pumps are easy to install and use very little electricity, usually less than $2.00 per year to operate. These systems even work with tankless water heaters, which is good since tankless water heaters take 10 to 20 seconds longer to get hot water to the fixture which means running more water down the drain.

Well, I think thats about it for my first blog post...

Bill the Hot Water Guy