Contributor: Alice Feng
TL;DR
Energy-efficient toilets use water velocity to remove waste instead of water volume. They can reduce toilet water usage by 20 to 60 %, or nearly 13,000 gallons saved per year. An average family could save up to $110 a year on their water bills. There are various types of energy-efficient toilets to install based on different situations. Amid the rising threat of climate change, extreme weather events like drought are leading to insufficient water resources for flushing sewage systems. The rising sea level will also impede the operation of the wastewater facilities in the near future.
Context
Toilet is something that, well, we use everyday. Therefore, choosing the right toilet is extremely important. Here are some facts about toilets:
More than 45% of water use in the average American home occurs in the bathroom, with nearly 27% being used by toilets.
Energy-efficient toilets (also known as high-efficiency toilets or water efficient toilets) are designed to remove waste by using water velocity instead of removing waste by using water volume. What this means is that energy-efficient toilets increase the velocity of the water when you flush and only use about 1.28 GPF (gallons per flush) as compared to older toilets that can use up to 7 GPF.
Like ENERGY STAR® for home appliances, WaterSense is a label for products that meet the criteria for water efficiency. The current federal standard for toilets is 1.6 gallons per flush. This federal standard passed in 1992, so if your toilet was installed before 1992, it most likely uses 3.5 GPF to 7 GPF.
In 2016, only 37 % of homes met the efficiency criteria for toilets but the toilet flushing frequency has remained the same
The average household has about 5 flushes a day. An older toilet uses 7 gallons per flush, a newer one could be as low as 1.6 gallons per flush. If it is 7 gallons that is 12,775 gallons per year on flushes. At 67% that would eliminate 8,559 gallons of water usage per year in your household.
According to the EPA, installing water conservation toilets can reduce toilet water usage by 20 to 60 %, which means nearly 13,000 gallons saved per year. If every old and inefficient toilet in the United States was replaced with water-saving toilets, the savings would be around 520 billion gallons of water per year. That’s the same amount of water that flows over Niagara Falls in about 12 days! By installing a high-efficiency toilet, the average family could save up to $110 a year on their water bill, and $2,200 over the lifetime of their toilets.
As we can see, installing an energy-efficient toilet can be extremely cost-effective. But what type of toilet is the best both for you and for the environment? Let’s take a look.
Before we run down the different types of toilets, we first wanted to introduce you to the Toilet Searching Tool powered by Map Testing.
Waterless/Dry Sanitation Toilets
Waterless toilets have lower environmental impacts than water efficient toilets and wastewater recycling systems. If appropriately designed, they can conserve water resources and keep effluent and pollutants out of waterways and the general environment. They can also save money on your water bill. They are often preferable to conventional toilets in environmentally fragile or water-scarce areas and are commonly used in RVs. Their price ranges from $560-2000.
The most common type of waterless toilet is the ‘composting toilet’ (CT).
Pros:
Doesn’t smell if used and maintained correctly
Waterless toilets can produce fertilizer if sufficient time is allowed and correct treatment conditions have been maintained.
Decomposition in the holding tank or container of a CT takes place through a complex biochemical interaction of factors such as temperature, pH, desiccation and digestion by invertebrates, all taking place over an extended time period.
The container is permanently fitted under the toilet seat, and never has to be fully emptied as the compost can be gradually removed when it reaches the end-product chamber.
Cons:
It may allow fresh material and pathogens (disease causing organisms) deposited on the top of the pile to contaminate the successfully decomposed end-product at the bottom of the pile.
If a problem occurs with the toilet, the system can be out of order until the problem is fixed because there is only one container. Sometimes the pile does not actually move down the slope of the container and can become compacted and very difficult to remove.
Product Example: Laveo Dry Flush:
a waterless and chemical-free portable lightweight toilet
bags waste and stores it in a cartridge.
No need for wastewater/black water pumping/dumping or adding of chemicals. Waste is automatically encapsulated during a ‘flush’ and hidden in a lined container under the seat. When the cartridge is expended, lift up the toilet seat and the trim piece just under it. Lift out the liner bag containing wrapped waste.
doesn’t need constant electricity, venting or any kind of complicated installation process.
We just discussed waterless/dry sanitation toilets. Next, the following toilets are all examples of energy efficient toilets.
Low Flow
A low-flow toilet uses only one flush feature (1.3 GPF). A high-traffic bathroom could benefit from a low-flow toilet by cutting down on flushing confusion. On average, a low-flow toilet will cost you $10.76 per year by replacing your old toilet that costs on average $21.27 per year to run. Low-flow toilets use 1.28 gallons per flush vs 1.6 gallons per flush over in-efficient models. Like many eco-products, low-flow toilets typically have a higher upfront cost than a less efficient alternative. it can pay for itself in less than 7 years, even though it’s more expensive initially. Don’t forget that you’re also helping to save the environment! Here’s a run down of the cost.
Pros:
Standard toilets us approximately 7 gallons per flush, while the regular low-flow toilet model uses 1.6 gallons per flush. (Some models are even more efficient.) This means an automatic reduction in you water bills each month, and over a full year the savings can add up to be tremendous.
Conserving water will also benefit the environment.
Cons:
Like most advanced technology and efficient home fixtures, low-flow toilets cost more to install than standard toilets.
They have been known to have more frequent problems with clogs because they are not as powerful as standard models. However, advances in hydronic power in low-flow toilets, such as pressure models, are starting to make up for this issue.
Estimated cost for a Low Flow Toilet in Princeton, NJ (08540):
Low Flow Toilets – Material Prices: $180.00 - $225.54
Low Flow Toilets – Installation Cost: $243.00 - $270.00
Low Flow Toilets – Total: $423.00 - $495.54
Dual Flush
Studies show that a dual flush system can reduce up to 67% of water consumption in comparison to a conventional toilet. Countries, like Australia, are even requiring that all new toilets are dual flush toilets due to the amount of water they save. Even some areas of the United States have laws that require dual flush systems to be used in new construction. They offer either a lever on the side or a push button system on top of the tank that allows the user to make a choice. Push one button for flushing liquid waste, which uses only 0.8 gallons of water, and the other one for solid waste, which uses 1.6 gallons., Here’s what the cost will look like:
Estimated cost for a Dual Flush Toilet in Princeton, NJ (08540):
Dual Flush Toilets – Material Prices: $270.00 - $315.54
Dual Flush Toilets – Installation Cost: $243.00 - $270.00
Dual Flush Toilets – Total: $513.00 - $585.54
Pros:
Dual flush toilets consume much less water per flush than ordinary toilets do. Standard toilets flush by using water to siphon waste out of the toilet bowl. Naturally, using water to push water involves a great deal of waste. In addition to the waste of using water as a power source, ordinary toilets always use the absolute maximum amount of water they have available. The siphoning system used in standard flush toilets determines that the toilet is done flushing when air enters the siphon, meaning that it always empties the cistern completely, even when a small amount of water is actually needed for the job at hand.
In addition to the environmental upside to saving water, this also reduces your water bill over time. Dual-flush toilets are also considered high-efficiency. This means that some states have rebate programs in place that help people to subsidize the cost of upgrading the toilet in their home to a model that uses less water. Certainly, if you have this type of rebate in your state, installing a dual-flush toilet in the home will be more affordable than buying an old, non-efficient model.
Cons:
According to Lowes, dual flush toilet models often require more cleaning and are more difficult to clean than standard single flush models. These toilets retain less water in the bowl, which may result in an increase in dirtiness. It’s also necessary to ensure that the water holes along the rims don’t clog as this can decrease the toilet’s ability to function.
Newer residential construction takes the needs of low-flush toilets into account, but dual flush models are not always compatible with older homes built when high-flush toilets were the norm. In addition, older plumbing may have developed sags, dips and other problems that prevent a dual flush toilet from working.
Power Flush
A power flush toilet uses pressurized air in the tank to achieve additional force when you flush. Power flush toilets usually make more noise, making them not ideal if they are located near sleeping or working areas. What are the pros and cons of the power flush toilet?
Pros
Efficiency. Pressure-assist toilets are much more efficient, thanks to their forceful flush. There is hardly ever a need to flush twice and toilet clogs are rare, even in aging plumbing pipes.
Water savings. These toilets help you save water. Each flush of pressure-assist toilet uses 1.1-1.2 gallons, compared to dual-flush gravity-flow at 1.3 gallons or single-flow (1.6). That can add up to 4,000 gallons annually.
Lower maintenance. A pressure-assist toilet contains fewer moving parts, meaning it will be less likely to break down and require servicing.
No condensation. Lastly, many homeowners and business owners choose pressure-assisted toilets because these toilets are not impacted by humid weather (readers in Miami know what I'm talking about). That’s because the tank-in-tank design reduces any amount of sweat.
Cons:
Noise. Pressure-assist toilets are popular within industrial settings, since they are far more efficient than gravity-flow toilets. However, most homeowners do not purchase pressure-assist toilets since these toilets tend to be rather loud.
Availability of parts. The inner workings of a pressure-assist toilet are not the same as a gravity-flow toilet. Because most hardware stores don’t stock these parts regularly, replacing or repairing parts components of a pressurized toilet is somewhat difficult.
Price. Pressure-assist toilets are more expensive than regular gravity-flow toilets. While a standard gravity-flow toilet can be purchased for around $120 to $300, a pressure-assist toilet may cost as much as $700.
Difficulty of flushing. The flush lever on a pressure-assist toilet must be pushed with more force than on gravity-flow fixture. This may make it difficult for a young child or a strength-impaired adult to operate.
Gravity toilets
This type of toilets can be met in 90% of houses and apartments. As the name suggests, gravity is what makes the water take wastes. There is no additional mechanism involved. According to Your Toilet Guide, the mechanism is very simple: you push the handle and the water goes into a bowl. Then it goes into a trapway and a natural syphoning effect appears. It helps the water take wastes to sewer pipes. The system is pretty simple and does not require many components. It has been developed many years ago and was the ultimate option until recently. One obvious advantage of a gravity-assist toilet is that it is very easy to repair. Plus, the components are usually available in stores.
Pros:
Low prices. Not only are they innovative, modern, and simple to use, but they also come at the lowest prices available—whether you purchase them in bulk for your home or business, or as a single unit. Whether you are doing a minor upgrade or a total bathroom renovation, a gravity feed toilet is a great one to consider.
Proven technology—they have everything you could need or want from a toilet, and on top of that they are also really durable and reliable. Gravity feed toilets use a technology that has literally been around for decades, they have just expounded on it and improved it over the years. Since its reliable technology, you know you can trust them and—since they are the most commonly used type of toilet—they are also relatively simple and affordable to fix when you have a problem.
Tons of designs and styles to choose from. Not only do these types of toilets come in lots of models to choose from, but they actually offer the most options to choose from when compared to other types of toilets.
Cons:
Water consumption: While they have some more water conserving options, these toilets will use up a lot more water when compared to other types of toilets. If you already have a high water bill, or if you want something that will help you reduce your costs overtime, then this is not the way to go. If you have low water pressure in your home then this won’t be the best option for you since it may end up requiring multiple flushes, thus using up even more water. If you think you may have this issue, make sure to figure out your average flushes per month and take into consideration the toilets gallons per flush.
Size: Typically,they are on the larger side, and not a great option for smaller bathrooms—and if you are worried about the overall “look” of your bathroom this is not only a comfort issue, but also décor issue. While there are smaller models to choose from, in the end they don’t compare to the compact size other toilet types offer.
Number of users. If you have a larger family and only one or two bathrooms you may want to consider a pressure assisted toilet instead, since gravity flush toilets consume a lot more water you will definitely want to try and cut costs where you can.
More likely to clog, especially if the building has cast-iron waste lines. Even though modern gravity toilets perform as well as pressure-assisted ones, if you are responsible for multiple toilets, consider getting power flush toilets to reduce maintenance needs.
If it’s not the best time for you to do an upgrade yet, you can also consider simple and cheap retrofits that can make a big change, both in saving your water bill and protecting our environment.
Toilet Tank Displacement Bag
It will displace 0.5 gallons of water in your tank so the toilet uses less water each flush. You can find them on Amazon for $ 6.44.
Toilet Fill Cycle Diverter
A plastic device that sends less water to the bowl and more to the tank while they both refill. Like the toilet displacement bag, a toilet fill cycle diverter could help you save 0.5 gallons per flush. You can find them on Amazon for $5.29 on Amazon.
Toilets in LMICs
WeForum 11/16/18
“The rise in extreme weather events is proving challenging to sanitation systems around the world. While the UN's Sustainable Development Goal (SDG) 6.2 calls for universal sanitation, 4.5 billion people globally lack safely managed services. On the other hand, extreme drought leads to insufficient water resources for flushing sewage systems. For example, according to Google Trends, on 28 January 2018, the search term "waterless toilets" reached a peak in searches coming from drought-hit Cape Town.
Nearly 55% of the world’s population lives in urban areas, and this proportion is expected to increase to 68% by 2050. In most densely populated cities in the developing world, untreated sewage and faecal sludge are major causes of environmental and water pollution. Globally, human waste converted to fuel could have a value equivalent to about $9.5 billion of natural gas, estimates a UN University report. During World Water Week 2017, the Toilet Board Coalition and its partners explored the business case for turning human waste into valuable resources such as fertilizer, animal feed and high-value proteins. They concluded that "there is a clear business case for building toilets and keeping them secure and well-maintained ... there is an economic incentive for creating a sanitation economy".
Various stakeholder groups have recognized the need for toilets that can not only withstand extreme weather events, but also help mitigate climate change. The Toilet Board Coalition’s Accelerator and Re-invent the Toilet Challenge, funded by the Bill & Melinda Gates Foundation, are investing in innovation in toilets and sanitation systems that are sustainable, recover valuable resources and can be scaled up. The Indian government also conducts periodic "toilet hackathons" for inventors to generate resilient and sustainable solutions. Sanitation innovators across the world are developing products based on the principles of the circular economy.”
Here’s a list of some startups aiming to improve access to toilets around the world:
Kenya
Installs container-based toilets in people’s homes for free and charges a small monthly fee to service them. Instead of dumping the toilet "waste", they transform it into a clean-burning alternative to charcoal. These briquettes are not only preferred by their customers due to longer burn time and lesser smoke, but they also save 88 trees for every tonne sold.
Developed an affordable dry sanitation system that produces a valuable fertilizer, promotes entrepreneurship and reduces pollution of water resources. The fertilizer, which is made from human urine, is branded as Aurin and is authorized by the Swiss Federal Office for Agriculture to be used as a fertilizer for every type of plant.
Developing and marketing different eco-friendly sanitation technologies. One of them is the Zerodor urinal, a waterless and odorless urinal that can save 50,000-150,000 litres of water every year. It can be retrofitted in existing urinals, and neither chemicals nor electricity are required, making Zerodor a "green" toilet.
Wastewater Facility
Septic Tank and Rising Sea Level
Newsweek 9/30/19
“A new United Nations report states that rising sea levels could render as many as 60 million toilets inoperable in the United States alone, as traditional septic systems are threatened by increased groundwater. The report also indicated that 64% of the septic tanks could break within the next 25 years, requiring annual repairs to continue operating. About 1 in 5 American households rely on septic systems to handle their toilet waste, according to the Environmental Protection Agency.The stuff in your toilet goes into an underground tank, where it breaks down and gets drained out into a leach field that’s at least 20 feet from your house. In order to function properly, those drainage fields have to be relatively dry. Rising groundwater levels are soaking the fields, making it more difficult for our waste to break down and get absorbed properly.In addition, erosion removes the necessary soft earth to filter out pollutants, resulting in public health hazards and groundwater contamination. And to make matters worse, increased rainfall, another climate change-related perk, is exacerbating the issue.”
Solutions:
Reform the way septic systems are regulated so that new systems are evaluated for their susceptibility to climate change before they’re put in. Researchers are already mapping out areas with infrastructure that’s vulnerable to groundwater level rise in coming years in states like New Hampshire.
Inspecting existing septic systems when houses change hands at the point of sale is a way to make sure that we’re checking in on how infrastructure is doing given current risk, and how it’s changed from 30 or 40 years ago.
Shallower leach fields rely on a narrower depth to treat water. Municipalities can install town-wide sewer systems in areas where household septic tanks don’t make sense. Frequent inspections are key, too.
Carbon Emission from Wastewater Facilities
Wired 01/23/19
“Currently, the stuff you flush in the toilet ends up in a facility, along with liquid waste from other industries like beer or wine making. All that organic matter sits in open-air tanks where microbes feed on it. They munch on the waste and release CO2 as a byproduct, and the facility then pumps the relatively clean (but far from drinkable) water out to sea. On its own, a person’s poop is carbon neutral: Plants capture carbon from the air by way of photosynthesis, you eat the plants, you produce the carbon as waste. When those microbes eat that waste and release the CO2 back to the atmosphere, it ends up right where it started. Except that the wastewater treatment facilities need energy to operate. Worldwide, wastewater treatment facilities account for 3 % of electricity consumption and contribute 1.6 % of emissions. ”
Solution:
Some microbes, like bacteria and microalgae, feed on CO2 itself. They would eat up the organic carbon and then convert the CO2 into chemicals like ethanol. Replace the typical microbes used in wastewater treatment with these CO2-guzzlers. You treat wastewater but also you reduce CO2 into something more valuable. In this setup, you pump CO2 from, say, a fossil fuel power plant into enclosed tanks full of wastewater. These plants are often located near wastewater facilities anyway; instead of their emitted CO2 going into the atmosphere, it would get funneled to the tanks for microbes to munch on. The wastewater facility would pay the power plants for their CO2 emissions, and would then use the microbes to produce valuable chemicals (like ethanol) to sell off.
Everyone wins, in theory: Fossil fuel power plants can say they’re cutting emissions, and wastewater plants get an extra revenue stream.
Making carbon capture technologies take off will either require legislation to mandate them, a new business opportunity, or both. The wastewater treatment plant would become a refinery.
Use wastewater byproducts, aka “sludge,” to produce biochar, a type of carbon-rich charcoal. When added to soil, biochar can improve crop yields and boost how much CO2 the soil absorbs.
Turn artificial wetlands into their own facilities of sorts: Pump the wastewater into one of these engineered wetlands, and plants would convert it into biomass, thus reconstituting CO2 as vegetation.
Companies have no incentive to do so since it doesn’t save money
