Water Conservation, Low Flow Fixtures, and Tankless Water Heaters

Low Flow Fixtures

Now days all faucet fixtures for residential plumbing are low flow devices.

While they do aid in water conservation efforts, they can be a bit inconvenient. They don’t save you water if you are filling a pot, getting a glass of water or where a measured volume of water is to be had. They can be a nuisance when you have to wait and wait for the sink to fill with water, or if you are trying to get hot water to the faucet.

Low flow fixtures cause the hot water to flow through the pipes more slowly, and so it takes longer to get your hot water. This can be especially trying when you have long pipe runs, or when your pipe is under a concrete slab and not insulated.

Slow hot water can lead to water wastage. It can take so long to get hot water at a fixture that many hot water users let the hot water run while they do something else before returning to see if it is hot yet. By the time they come back and check they are running hot water down the drain.

At this point energy is being wasted as well as water and the energy to heat the water being run down the drain is substantial… much more expensive than the water being heated.

Tankless Water Heaters

Tankless water heaters are not water conservation friendly to begin with. It takes a tankless unit longer to deliver hot water than a storage water heater since it has to heat the water first which can take 10 to 20 seconds longer than a storage water heater would deliver it.

To obtain the hot water temperature you desire you typically mix hot and cold water to get the desired temperature. This works fine with a storage water heater but can be a problem with tankless units when lower flows are used.

To turn on the tankless heater you must draw ½ to ¾ gallons per minute, depending on the water heater model you have. The outlet temperature with a tankless unit does not change as long as you don’t exceed the maximum flow, so the minimum flow of say ½ gallon per minute is at the full outlet temperature.

If you need to mix half cold and half hot to get the desired temperature you are then forced to use 1 gallon per minute which can often be a much larger flow than you need or want. This of course results in wasted water being run down the drain.

Hot Water Demand Systems

Hot water demand systems can overcome the inconvenience of slow hot water caused by low flow fixtures. Hot water demand systems pump the water to your fixture fast without running water down the drain. Your hot water is faster and you save time water and money.

A hot water demand system typically locates a small pump under the sink furthest from the water heater. When hot water is desired the user pushes the start button which activates the pump and speeds hot water to the fixture. The cooled off hot water from the last hot water use is returned to the water heater through the cold water piping so no dedicated return line is needed.

Demand systems are especially nice when used with tankless water heaters since you save both energy, with the tankless heater and water, with the demand system while having the convenience of fast hot water.

Solar with Tankless - Water Heater Guide - Water Conservation

Saving Water and Saving Energy - Human Behavior

Saving water and saving energy in a residential home setting, is largley a behavioural problem. If you observe how people use thier water for instance, you can spot wasteful behaviors all over the place.


Yard and lawn watering behaviors that don't save water

There are the obvious wasteful behaviours, such as watering the lawn at the wrong time of day, or over watering, and even watering the sidewalks and streets. The behavior in these cases is I guess, lazyness. All are easily corrected, but require someone to take the corrective action.


Low flow fixtures VS. behavior - To save water and energy

Once of the most often used water conservation methods or device is the low flow fixture. Low flow fixtures are a double edged sword. They can provide significant savings, and in turn can inadvertently cause a lot of waste.

For example, low-flow fixtures limit the maximum flow rate available from the fixture. This translates to lower water velocities through the pipe, and thus require a longer wait for hot water. However, a common reaction for those people who have very long pipe runs, is to turn on the hot water in the shower and go do something else while the shower gets hot. When they return, they often return to find hot water running down the drain.

Depending on how long the water ends up running before the human returns to use it, the savings in water is negatively impacted, and can even end up wasting more water than if the low flow fixture had not been used to begin with.

In the previous scenario energy is also being wasted. The cost of heating water is much higher than the cost of the water being heated. Running hot water down the drain is very expensive in terms of money savings... or loss!


Save Water - Behaviors in the Bathroom

Studies have shown that 80 percent of the time a typcal hot water draw occurs at a bathroom sink, the hot water doesn't make it all the way to the fixture. Most of us are guilty of this behavior... impatience... we turn on the hot water to wash our hands and we can't wait for the hot water so we start washing, only to finish about the time the water starts to warm up.

If you don't end up using the hot water, and all you've done is filled the pipe with hot water which will then cool off, then you have essentially wasted the energy. Better to not use the hot water faucet at all.

There are a whole lot of behaviors in the bathroom that can lead to wasting water, things like letting the water run while you brush your teeth, especially warm or hot water, running water whle you shave, lingering in the shower, etc.

The laundry room and saving water and energy

The obvious answer to saving water in the laundry room is to use the smallest load setting possible while still having enough to get the clothes clean. Using cold water instead of warm or hot saves energy as well.


Save water in the kitchen

The kitchen also suffers from human behavior caused water wastage. Single handeled faucets along with human habits are a contributor to energy wastage. If you don't swing the handle all the way to the left when drawing cold water, then you are drawing some hot water as well... a waste of energy.

Running the hot water to get your dishwasher really hot water is wastefull of water, running water to rinse dishes thouroughly, even hot water, when your dish washer doesn't need pre-rinsing, etc.

Save water and be energy efficient

There is one solution to several of these water saving problems... a demand hot water system of course. In the bathroom it will save energy and water by eliminating running water down the drain while you wait for hot water to arrive as discussed earlier.

In the kitchen it can eleminate the wasted water that you run to get hot for your dishwasher etc.

When you really do need hot water you get it more quickly and without wasting any water which saves you additional energy. It's the perfect companion for low flow fixtures!